Video of debris pile from July 12th from different angles. Video of debris pile 7-12-21

Some thoughts on the past 5 pages of this thread.

Security cameras - the outdoor surveillance video of the building collapsing - you can bet that camera / NVR / hard drive / SD card, etc... are all in a secure place for further analysis / evidence. There are a number of neighboring properties that may also have cameras recording and those too were all likely canvassed early on to preserve footage before it could be overwritten. Existence of these recordings, if any, aren't being made public.

The collapsed building security camera NVR/DVR system. If they have one - it's likely one of the first things they looked for to preserve it. If they found it, assuming it was still functional - they haven't said anything yet publicly (no reason to at this point). But it would likely be in a secure place for later analysis / evidence for now.

NVR/DVR systems are getting cheaper, with more storage space and higher resolution. No telling what type of system they had showing the initial collapse and really no reason to have motion activation on any type of system these days. At my home, the $300 system I bought on Amazon has 4 high-def cameras recording 24/7 and a 1 TB hard drive that holds a week of high-def 30 fps video. Cost shouldn't be a factor at this point. But like anything else these things need to be maintained too.

Some general thoughts about the possible causes. Most of you have some pretty good ideas about what likely happened and I'm not going to doubt those of you who are professional structural engineers for a living and know this stuff inside and out (not my wheelhouse). But until we know more from the people who actually have boots on the ground at the site - it's generally speculative at this point.

From what I can see from everything here, it took 10-15 minutes from the initiating event - whatever that may have been - to collapse. Something didn't snap and the place instantly tumbled down. This means the occupants had time to evacuate but there likely wasn't a plan or someone smart enough to realize something was very very wrong and sound the alarm / start pounding on doors, whatever it takes. A few people had the wherewithal to know something wasn't right and got the hell out of there just in time but most others in the affected portion of the building weren't as fortunate. The question I have was that security guard/front desk person asleep when it happened - or just unware/incompetent? No offense to anyone who works in security, but most are just warm bodies to satisfy insurance requirements and little more.

Unfortunately the condo association and residents found themselves in a very bad situation and it was too late to do anything about it (not that they didn't try as repairs were just starting to get underway). But egos, incompetence, pride, stubbornness, frugalness etc... all delayed needed repairs over the years and to get things moving fast after the 2018 report. Volunteer boards, as well meaning as they may be, are generally ineffective and unqualified in these areas - and serve little more as go-along to get-along governing bodies / social cliques (been there / done that).

Much will come out of this and like any disaster on this scale, many lessons will be learned and many changes will come to both existing and new construction of this type. Unfortunately it's disasters like this that spur changes (i.e., the Rochester Holiday Inn fire in 1978 and the MGM Grand Casino/Hotel fire in Las Vegas in 1981 were catalysts for hotel fire prevention / safety).

I wouldn't be surprised to see some buildings ultimately condemned and demolished because they are deemed too high of a risk for continued occupancy and too expensive to repair... and insurance costs for these types of buildings will go through the roof as a result.

Let's not forget that a lot of people were asleep. You aren't leaving if you're asleep.

spsalso

July 12th at 2pm - Seeing widespread reports of street-flooding on social media all across Miami Beach and points northwards
Nop, no evidence of changing climate here...

SF Charlie
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Surfside recommends owners of older buildings hire geotechnical engineers to study ground below structure

"Surfside Mayor Charles Burkett and structural engineer Allyn Kilshimer, who the town hired to help with the investigation into why Champlain South collapsed, explained why they are urging the owners of older buildings to hire a geotechnical engineer.

“We don’t know why the building fell down and it is possible there were issues below the surface,” Burkett said."

Do you think the city is trying to cover their ass or have they found something pointing to geotechnical issues????

Arses, clearly.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

Hi everyone,

New here, but have been following these threads since the beginning. Such a fascinating discussion, thanks for everything so far.

I wanted to go back to the Ring video from unit 711 because I think it's one of the most interesting pieces of evidence. Someone in a previous post noted that the direction of the falling debris changed over the course of the video, which may indicate the room is actually tilting. I hadn't considered that before, and wanted to investigate a bit further.

I've created a few GIFs of the Ring video which may be relevant to the discussion of whether the column in the parking garage is indeed missing.

First, I made a very short GIF combining the first frame (which I suspect was captured by the Ring cam before anything happened - nothing seems out of place) and the last frame only, to demonstrate how much of the room has changed over the 13 second duration.


It's obvious that the formerly rectilinear room has become quite deformed in the last frame. In particular, it looks like the entire floor is sliding to the left (or the ceiling sliding to the right), causing the wall on the left and the drywall column between the unit doors and kitchen to become noticeably angled. Also, the couch and the refrigerator (EDIT: not the stainless steel refrigerator, but whatever the black rectangular shape against the right wall is) on the right side seem to actually lift up. The refrigerator seems to move up quite a bit.

I suspect the movement of the black-refrigerator-looking object and couch on the right are due to the south side of the room falling, while the east-west column line, which runs right next to the black object, is not falling (or not as much), causing the black object and part of the couch to seem like they are lifting upwards.

Next, I took the Ring video and sped it up by about 8x, which exposes how the building is slowly, but actively, deforming under some sort of unsupported load condition:


Finally, circling back to the theory that the room is tilting during this time, I roughly rotated the view to match the direction of the falling material from above. One thing I'm not certain of, could this change in direction be simply due to a breeze in the room? I doubt the windows were open, but maybe they've broken by this time. If this is due to wind, then this theory falls apart, but if it's actually indicating the direction of gravity, then I think the room is tilting during the duration of the video. I had to reduce the framerate here to keep the file size down.


It seems like a pretty extreme angle of course, but what's interesting is the right wall here is exactly on the column line we've been scrutinizing in the Tik Tok video. Seems like structural changes along that line may be impacting this room (unit 711). Also, this would explain the strange snapping and movement of the TV box, and sort of rationalizes the strange lateral shifting of the floor and ceiling.

This video makes me think something has shifted so significantly in the building structure - several seconds before progressive collapse - that this room is both severely deformed and possibly tilted, and the collapse has already started, albeit very slowly. A missing column at the building line could cause this, but I know the column some think may be missing is actually only supporting the pool deck, one bay to the south. I don't think that column alone would cause the entire building envelope to sag, but maybe if it is missing, or if the pool deck collapse had also destroyed another column nearby, or some beam/connection at the building envelope and pool deck, it could be causing the entire facade of the x11 stack to start sagging? Perhaps there would be slow, visible movement of the facade in the exterior surveillance video, but it's too subtle to trigger recording until the moment the collapse picks up speed? This could also account for the alleged missing penthouse level in the video - maybe this facade has been slowly sagging for several seconds and descended many feet before the progressive collapse begins.

Probably a stretch, but I'd be curious to hear real engineers' thoughts on what's happening in this video. How is the structure twisting and deforming to cause what we see in the Ring video?

This probably isn't the place to get into the global warming climate change _h^o_a^x debate. But... it's generally sage advice not to build/develop on the waterfront either. Sooner or later, mother nature will win - whether it be storms, erosion, flooding, rising sea levels, whatever the case may or may not be. Building on a sandy salt water beach is one sure way to give her a head start. Growing up on Long Island - this has been evidenced and documented many many times over the past 200 years via hurricanes and natural shoreline erosion - especially on the barrier beaches (i.e., Fire Island, etc...). Yet, people keep building / rebuilding knowing the risk. I mean who doesn't want a view of the ocean? Some places are best left to nature. There's plenty of places to build housing further inland.

Quote (waross)

waross (Electrical)13 Jul 21 02:17
Good catch Nukeman948, thanks. Correction made.

Quote (nolascience):
Aren't those Electricals so cute with their talk of phases, breakers, and neutrals?

Back at you:
Aren't some of those those Structurals so cute with their mangled understanding of phases, breakers, and neutrals?

@waross,
I wouldnt go so far as to call our friend NOLAscience a "structural"...

@NOLA
What is your angle? Ever since you've been active on this website, I suppose starting with the new orleans hardrock hotel collapse..., your posts have always had this sort of accusatory flavor - always looking to blame SOMEONE right away... I think I can speak for many here by saying that a lot of your input is not very constructive, and some of your posts simply do not belong on this forum. It is unfortunate that we're devolving back to pissing match type posts as seen in the warrenslo era (my post here not excluded...).

Quote (Jbourne / Demented)

I'm also curious about Demented's question earlier:
Quote (Demented)
Does anyone by chance know what the theoretical compressive strength of column M11.1 should have been in an ideal environment?

6,000psi spec'd. Look at the left side of the column schedule on the original struct drawings.

Quote (Keith1)

Keith_1 (Structural)12 Jul 21 12:40
Even IFF a car took out a column, there is so much redundancy built into a structure that it is a non-event. This structure has has been subjected to multiple instances of high asymmetric pressure loads (hurricanes), and those pressure are way greater than loading a roof with a few tons to support a swing stage, or taking out a single column. I will state with 100% certainty that a single column, beam or any other discreet element will not cause a catastrophic failure like this, in a structure that has been loaded in the manner that this building has.

I will have to 100% disagree with you. The complete loss of a column in this building can, and likely did cause a catastrophic collapse like this. Lateral loads can indeed effect vertical forces on non-LFRS members, but to say a hurricane will impart more severe loads on a gravity member than a total loss of a column is simply not true. If you disagree, please discuss. The only possible way I could see this being the case is if you consider the absolute lack of shearwall in the E/W direction causing story drift that imparts significant moment into the columns, and this would be more apparent in higher stories, not at the base. Even then, it is likely that unbalanced moments at column/slab joints would initiate a punching shear failure before a failure of the column itself. Who knows, but the building certainly collapsed.

Quote (Awestruck)

Awestruc (Structural)11 Jul 21 04:35
I don’t see how unbonded PT tendons that are stretched to 70%-80% of their ultimate tensile strength can offer any shear strength. They would be under extreme tension + shear = pop.

Modern connections are more robust due to the use of stirrups or stud rails or puddling of high strength concrete atop columns (questionable).

The pool deck design had no real shear reinforcement. The design concept was
To design the concrete thickness to handle the shear. Then to design the horizontal top bar for flexural tension, and then place a certain amount of horizontal rebar directly over the column for good measure. This is the same philosophy with modern PT.

Integrity tendons support the failed slab via catenary action. All prestress in the slab and tendons goes to zero as soon as the slab fails. They offer effectively no shear strength. And yes, two way mild reinforced slab design and modern PT design share many similarities. One critical difference is that there are no splices in PT tendons. I would wager a lot of money that not a single one of the top bars (or any bar in this building) failed in tension. All discontinuities are at lap splices. Hence the importance and effectiveness of integrity tendons.

Quote (3DSoftwareDev (Computer)13 Jul 21 03:59)

how much of the room has changed

I'm stunned by how far out of perpendicular the (post? wall?) between the door and the counter moves!

SF Charlie
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DOLD

Let me guess if a PT tendon fails, the building is going to fall down. In reality, you abandoned it.

Quote (Keith_1)

Let me guess if a PT tendon fails, the building is going to fall down. In reality, you abandoned it.

What are you talking about? Losing a PT tendon isn't quite the same as losing a column..? As I described in a previous post, integrity tendons would not necessarily prevent a collapse in the case of a column failure, but the intent is to prevent a pancake type collapse in any event.

Quote (zebraso (Mechanical)12 Jul 21 09:20)

Can someone tell me this is not what it looks like.

What does it look like to you???

A Cat-Racoon Hybrid?

I still thick I see a Giant Yellow Jacket

SF Charlie
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Dold

Seriously, do you truly believe that a single column is under that much compression, that its failure would result in a 12 story building failing?

I'm still lurking but nobody has changed my mind. The roof anchor work caused the penthouse roof to collapse onto the pool deck.

1) The green bag in the tick-tock is a roofing material bag (similar to that left behind on the existing building. There's no way it's a plant, haven't any of you seen a plant upside down, it's brown dirt. Photo of left over bag:


2) The penthouse collapsed first, no matter how you look at the pool video (which was activated by movement or has earlier shots not shared with the public) those floors are missing, get that through your head!

3) I requested the recent inspection records and the city replied we posted them not realizing they only posted to 2019 (at that point.) They replied days later after they posted the info from 2019-2021. Literally, the only work on the building is to the roof in the last weeks. Buildings don't just collapse unless provoked. The demo experts (CDI) said the rebar they dealt with was different but not rusted, damaged, etc. If the rebar was wrong this building would have fallen during construction or shortly thereafter. If the rebar is wrong, in a 40-year old building, the first thing you check before roof work is to make sure the roof work can be withstood. The structural engineer clearly had an agreement with the roof anchor guy, I'm not sure all of you understand how these rackets work. Most roof anchor companies use their own structurals and because of OSHA rules get a yearly maintenance fee for the life of the anchors they install. It's government at its finest. And, it's not in the IBC.

3A) IN a recent debris pile photo - I can't find it again - they have placed a green bag (same color as roofing) next to the column which was damaged by the pool deck cars. Plastic doesn't get damaged too much by concrete, I'm curious about this. Can anyone find this photo - it's recent?

This entire discussion has digressed into complete BS from some members, if you can prove MY theory wrong, please do it with evidence. Nobody has thus far, even the guy claiming the "C" on the gate was not an AC unit was ignorant to the fact the C was right above where he claimed the "C" to be.
CHANGE MY MIND!

-W

Well lookie here, KCE is drilling to the ... Penthouse... boom...

Link

One thing I would like to point out with the 711 video... a lot of the room appears to move to the left, but I think in reality, the extreme tilt of the room is actually causing the table the ring camera is on to slowly slide down to the right.

I've also noticed a lot of people claim the falling debris to be from the popcorn ceiling... and I think it's too fine to be popcorn. It looks like powdered concrete to me. I thought if the camera is backed up to the concrete block wall, that it might be coming from cracks grinding across each other in the concrete block wall. Is if possible the slab has cracked above the camera and this is concrete dust from cracks in the slab moving?

BKNJ

Quote (3DSoftwareDev)

WOW, you have the exact same idea I had! Last night I made a GIF alternating between 1st and last frames, and a 50fps version of the active video frames to show there was slow but eerie movement.

I believe I can disprove the gravity shift idea, though, and attribute all the skewed movement to wind. The parabolic bounce of the particles near the "desk" the cam is sitting on is still symmetrical across the top-down axis of the camera viewpoint, all the way till the last particle bounce near end of video. The "desk" is however lifted slightly from the left at the end, which I attributed to the floor warping upward toward the wall at the southwest and northeast corners, at minimum.

Quote (3dsoftwaredev)

I finally created an account to thank you for the GIFs and analysis you’ve contributed. I too have been following this discussion closely and believed that the Ring video contained valuable clues to the movements of the building in those final seconds. I lacked the time and ability to illustrate it and you have exceeded what I could have hoped to present. Some observations:

•Can we pinpoint the precise location and direction of this view, on a floorplan? This will help make sense of the perceived distortions
•I don’t think air movement is a large factor in dust trajectory but it should not be ruled out, A/C registers puffing due to being crushed/pulled, large objects falling outside camera view, broken window as suggested, etc. I am intrigued by the displacement of the dust vs the frame of reference, are we seeing the room shift as the dust continues falling, some combination?
•In the last GIF on the upper left there is something interesting happening, a crack forming or the wall has changed shape perhaps
•Can anyone identify the precise device that recorded this? It appears to slide across the surface it is resting on, what size of deflection/force could be expected to cause that?
•The “old” initial frame is a bug that turns out to be a great feature here. Question is, how old is it? Could it be from the last activation (minutes ago, hours ago, why did it activate, loud noises perhaps?), or is it from a few seconds prior? Knowledge of the device can inform this.
•Timing of video end coincides with loss of power but there are delays due to latency in wifi connection, server-side activity. Just some disorganized thoughts on the element of time with regards to the footage.

Finally I’ll just say that the visual of the upper floors perhaps failing first due weaknesses/flaws, and slowly sagging down, hanging on by threads of rebar is... chilling.

Oh and about the “green plastic”... I guess not too many people have done any major home remodeling and filled up a $25 Bagster... at least that’s what that shade of green and those yellow lifting straps looks like to me!

SFCharle: "What does it look like to you???"

I didn't really want to say it, but every time I see this picture, it looks like a body splayed out. Torso/shorts are teal green, left arm straight and white, left leg towards us, right leg perpendicular with the knee bend at a 90 degree angle.

I'm sure it's just an over tweaked image that my pattern matching is unable to cope with... but once I saw it, I can't unsee it.

BKNJ

Quote (warrenslo )

Well lookie here, KCE is drilling to the ... Penthouse... boom...

If you think that somehow validates your weird theory that roof anchor work caused the penthouse roof to collapse onto the pool deck - think again.

Quote (3DSoftwareDev (Computer))

Great work. Did you try rotating the camera back as well as sideways? Seems to me the divergence of the falling grains is increasing, IE the fall of grains is trending more toward the lens as well as laterally. Thus the room is tipping back toward the camera - as well as the deformation you have identified.
General comment: I interpret murky pictures for a living (seismic). It is right to try to interpret that garage murk, but I wouldn't be staking a reputation on anything so far.

Quote (spinspecdrt)

Do you think the city is trying to cover their ass or have they found something pointing to geotechnical issues????

There is always ass covering with something this big, it's the nature of the beast. I think there's also a genuine "how the hell did this happen?" from all levels of government and the public. Part of it is likely considering all the possibilities, particularly because there may be many contributing factors.

There's also the very public statement by the geotechnical professor that 30 years ago it sank 2mm (possibly per year, possibly more, possibly less, possibly insignificant, possibly significant). If they don't properly study the geotechnical side, questions and doubts will likely remain.

Right now, they are very likely in abundance of caution mode.

Quote (3DSoftwareDev)

Probably a stretch, but I'd be curious to hear real engineers' thoughts on what's happening in this video. How is the structure twisting and deforming to cause what we see in the Ring video?

Excellent work on the images.

It's not my field of expertise, but the only way I can make sense of the 711 video is M9.1 failing as the last step before major failure in the tower. The SE corner of that room appears to slowly drop maybe 5 feet relative to the rest of it; that can only happen if M9.1 is basically gone somewhere below it, and the basement makes the most sense when we see the video from the north and factor in the heavy step slab/beam hanging off it. The loads initially redistribute onto adjacent columns, but they soon overload or fail due to the pull from the twisting and sagging slab. The next column to fail overwhelms the structure and the rapid collapse begins. I'd guess L9.1 next, possibly K9.1 simultaneous to that, as they are also dealing with the patio step-slab failure. The failure of M9.1 was probably due to the abnormal loading and damage done to it as the patio failed.

Sometime ago, one of you posted, complaining of no aerial photos since to implosion. I apologize for not remembering who. I've checked Google every day since, and none have appeared. I've also read in the news, an item that TPTB are providing extra security "since the collapse is a holy space". I wonder if TPTB are discouraging the press from posting aerials for some similar reason. (I think I may have just abused the word reason).

SF Charlie
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Quote (warrenslo (Structural))

Well lookie here, KCE is drilling to the ... Penthouse... boom...

Kilsheimer is evaluating hunches, and the hunch I think he was talking about in that clip, which I haven't seen discussed here, is that the penthouse addition could have been constructed without adequately modifying what would've been the original roof now turned 13th floor. So there might be slab or column issues, waterproofing where you wouldn't expect any, and numerous other complications I'll leave to the experts to reason through.

And sorry about your roof/roofing materials theory, I've seen no update affecting the chances of that being the trigger. You've seen the blue-green patio chairs previously outside 111, right?

Quote (BKNJ (Computer)13 Jul 21 05:04)

I didn't really want to say it

Thanks for clarifying...
I didn't want to say it either, but to me I see a red face to the left, body on it's side...
wasn't sure it wasn't the devil given the horns and all...

SF Charlie
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Quote (SFCharlie (Computer))

A Cat-Racoon Hybrid?

I see. Well the intent was to frame the crop around the teal green colored object. That was first noticed on the second page/part of this ongoing thread and I don't think anyone concluded whether it was teal colored foliage (which btw was the first mention of planters in the basement by association) or - whether there was the idea of it being the green colored tarp covering used for the roof rolls. Neither of those would I expect to be teal in color based on what I think plants look like or the photos of the actual tarps seen on the roof. So unless a cat-racoon hybrid also happens to be teal I think you may be missing the main focus of the image.
And ok I'm being a little coy I admit it. So maybe there is no teal colored object or material at all.

Quote (Keith)

Seriously, do you truly believe that a single 16" column is under that much compression, that its failure would result in a 12 story building failing?

We pretty much all agree that there was much more going on than just a column failing in isolation.

In my opinion and some others' too, the failure of the pool deck slab had a significant horizontal effect on one/some of the columns at the lobby level.

What about that other illegally demolished building (5775 Collins Ave.) where they were ripping out columns with a dozer? I think it is actually quite enlightening. GRANTED: I don't know exactly how many columns they had ripped out but the point stands. Especially when your (CTS's) diaphragm is only dragging into your (CTS's) 8 ft long shearwall with a couple of #4's. Also note that by all accounts i have seen, these guys were taking out columns 1 by 1 - no explosives.

From https://www.youtube.com/watch?v=f4Ty0OzSNz8 around 0:30.
1: notice the column adjacent to the collapsed column is still relatively straight
2: not so straight anymore and we are forming hinges at the slab and also buckling the columns at both locations to the left of the collapsed column
3: observe how much the entire left portion of the building has moved from it's initial position. A few feet at least.










Yes, I believe the loss of a single column can indeed initiate a progressive collapse. Read: Alfred P Murrah (well...two columns in that case), etc.

Quote (BKNJ)

I've also noticed a lot of people claim the falling debris to be from the popcorn ceiling... and I think it's too fine to be popcorn. It looks like powdered concrete to me.

To my eye, these are smaller, lighter, more bouncy, and more consistently-sized debris chunks, which would likely be from drywall versus concrete. I think the units in this building had simple painted drywall ceilings, with no exposed slab, so it's more likely this is debris from a drywall sheet snapping above the camera. I wanted to also point out, the "popcorn ceiling" term is not accurate because these ceilings, as far as I can tell, were finished with smooth, painted drywall, not the textured/dimensional stuff you might find in cheap or outdated apartments.

Quote (BKNJ)

I thought if the camera is backed up to the concrete block wall, that it might be coming from cracks grinding across each other in the concrete block wall. Is if possible the slab has cracked above the camera and this is concrete dust from cracks in the slab moving?

I think the camera is backed up against the glass doors of the unit. Which answers one of rodface's questions:

Quote (rodface)

Can we pinpoint the precise location and direction of this view, on a floorplan? This will help make sense of the perceived distortions

Yes, the unit is the 11 on this plan, on the 7th floor.

The camera is in "Unit C", somewhere just inside of the balcony doors and windows. It's facing north toward the hallway, in the central section that collapsed first.



See this Reddit thread if you haven't already: https://www.reddit.com/r/CatastrophicFailure/comme...

Quote (rodface)

The “old” initial frame is a bug that turns out to be a great feature here. Question is, how old is it? Could it be from the last activation (minutes ago, hours ago, why did it activate, loud noises perhaps?), or is it from a few seconds prior?

Great feature/bug indeed. I was very thankful for that first frame - an incredible reference opportunity. I assumed it was from just prior to the first frame, but you're right, that's not proven.

Quote (rodface)

I don’t think air movement is a large factor in dust trajectory but it should not be ruled out, A/C registers puffing due to being crushed/pulled, large objects falling outside camera view

I had thought about HVAC playing a role. The behavior change seems fairly linear, so something would have to start blowing and keep blowing in the same direction consistently. There's also not a lot of turbulence in the falling of the particles.

Quote (rodface)

Timing of video end coincides with loss of power but there are delays due to latency in wifi connection, server-side activity. Just some disorganized thoughts on the element of time with regards to the footage.

Yes, I've wondered what else this little heroic camera would have caught if it had kept transmitting data until the room was pancaked. I think we're missing maybe a second of the room's final moments.

Quote (AusG)

IE the fall of grains is trending more toward the lens as well as laterally. Thus the room is tipping back toward the camera - as well as the deformation you have identified.

Yes, it seems to me the room is also falling backwards, which would be consistent with the initial frames of the exterior surveillance footage, where the facade is falling first.

Depending on how much movement is actually happening here, I am surprised that there's such a small, localized area of visible debris from the ceiling. I don't see any other failures in the room causing debris in this video. On the floor however, I suspect the floor slab is hinging causing the refrigerator to raise up and tilt to the north.

Well lookie here:

Link

Quote (Auri)

And sorry about your roof/roofing materials theory, I've seen no update affecting the chances of that being the trigger. You've seen the blue-green patio chairs previously outside 111, right?

No need to be sorry. Basically, all the evidence against roof anchor theory has been BS, for example, in yours, there was no blue and only green in Tick Tock. And the green was the EXACT color of the roofing bag left on the remaining building in multiple after-collapse videos.

Also, your "hunch you think he was talking about" we are engineers we don't go off hunches - please provide evidence KCE is looking at this for your reasons. I provided evidence they would look at the penthouse, you haven't. I have provided plenty of evidence that others have further validated, including the city's permit logs. Please provide evidence.

CHANGE MY MIND.

Quote (SFCharlie (Computer))

I didn't want to say it either

I mean same here. I don't want to joke about it either if there is the remotest possibility that's what it is. It could be a victim. And I did not process the image to bring out something that was not there. I certainly did not have that intent. The image I copied from I think Yahoo News (ok first questionable thing about it). I doubled the image resolution by resampling with bi-cubic with detail retention intent. Then I did noise reduction and I think level adjustments - maybe automatic and manual, jpeg artifact removal and sharpening and resaved it with the highest jpg quality settings. Of course that in itself is not totally innocuous. But I think it preserved it well enough. The total unknown is the resolution of the phone camera. But I think a safety check is to look at the no parking sign (whatever it says) as you pointed out. You know how big the features are in the lettering. If they cannot be resolved then anything smaller than that in detail must be imaginary. But there aspects of what you see in turns of outlines that are larger that can be discerned straight lines or curves (shapes). So say you thought you saw horns. Nope. I look at it in terms of how many data points have to combine to put something that looks familiar into the right proportions, colors, overall shape and size to fit. You know how hard it is for people to fake photos of people that are pieced from multiple sources to even get it into the right proportion and perspective. You can tell. They almost never get it right. What are the odds of it happening randomly? And rest assured I know nothing about that so I could not do it if I tried.

Edit: I should have done a control. Same source image cropped with no adjusments except luminance levels to bring out the dark areas. And when I say Yahoo News as the source image I mean the tictok image that included the frowny face (whatever) that they published. I enhanced it and cropped it. I did not mean I found the image cropped as such as though someone was sensationalizing this and then I messed with it some more. I was only trying to clarify the "green" actually when I got a bit of a shock. I don't want to even look at it again truth be told.

SFCharlie,

Looks like a tired driver of a vehicle slumped over the debris, after crawling out of their vehicle thats just knocked down a column. Please insert thought bubble "opps" near them.

There could be a car under the debris right?

@zebraso/BKNJ - I was going to make a quick and sloppy overlay of the Philly Phanatic's head, but now I'm feeling incredibly unsettled. I'm trying to make myself feel slightly better by not seeing anything resembling the human form in Electronbelt's enhanced frames. And you would think something so ghastly would be more readily apparent to the woman filming, but it's hard to tell what she could actually see from her vantage point. Then add feeling what must have been sheer horror topped off with a surge of adrenaline...I feel terrible for her and her husband.

Speaking of the aforementioned lightened/brightened frames, does anyone have any additional impressions after looking at them? I feel like the shapes in the foreground of the debris pile are spectacularly delineated, but I'm not sure if that's a genuine or artificial byproduct of the method of enhancement. To me it looks like a beam (too long to be a column?) The segmentation is definitely interesting. And then the background just above it appears to be red in color, but again, how much of that is artifact?

I wonder how close they have been able to get to this actual area as they're excavating, it's hard to tell from the site walkthrough video. And for that matter, how long it will be until any of that information is actually released...for all we know, they have video from inside the garage itself. I'm really hoping they do have a lot of video from a multitude of angles, as has been suggested.

@Rodface - I wholeheartedly agree with you on the Bagster, I thought the same thing on those earlier shots that showed them up close on the roof. Filled quite a few of those over the years, I'm all too familiar.

Here's my take on the apt 711 video. Firstly an approx. camera location & orientation:
https://files.engineering.com/getfile.aspx?folder=...

A realtor's 360° tour of the unit directly below, 611, is available here for reference, note height/placement of glass doors: https://www.compass.com/listing/8777-collins-avenu...

I'll also reference @3DSoftwareDev's excellent sped-up GIF above, 5th post from top of this page, in making these observations:

1. The particle trajectories - falling vs. bouncing - indicate that many are blown or launched from the ceiling not at the very start but as the clip progresses. Gravity is still pointing close to downward even near the end of the clip, see two consecutive frames I've picked out near the end: https://files.engineering.com/getfile.aspx?folder=... This means a wind developed above over the course of the recording, pointing east and probably also to the south. The sliding glass doors are immediately south of the camera, and you'd expect them to be closed when occupants are out.

2. While the floor 8 slab appears to be sliding east relative to the floor 7 slab, concrete floor slabs are quite resistant to compression, so either the building's 8th floor slab was buckling/twisting wholesale, or the columns in the L group are sinking relative to columns in M. IMO the latter is far easier to explain, and would be consistent with the observed deviation in gravity near the end of clip.

3. If the columns and thus walls on the left are sinking, for the floor to remain flat, the right side must tend toward an obtuse angle with the wall (seemingly verified by tall dark furniture next to kitchen) and the left side must turn acute. That the "desk" the camera sits on steadily slides to the right could be explained by the wall slowly angling inward and pushing on it.

4. As you know, a square of fixed length will decrease in area as it turns into a parallelogram. Likewise if a wall of columns starts sinking and the floors remain attached, adjacent walls & columns get pulled in and a substantial amount of air must exit. That could explain the northerly breeze. Additionally - and I may be stretching it - what looks like some heavy smoke that creeps along from entrance area across the bar stools near end of clip may be indicative of the hallway columns/walls being pulled southward and forcing debris-laden air into the condo unit - kind of feeding into what might be obvious from other security cam footage, that the north section followed the south section in falling.

• https://files.engineering.com/getfile.aspx?folder=4a373d3a-92f3-485b-9c33-9

Quote (warrenslo (Structural))

Basically, all the evidence against roof anchor theory has been BS, for example, in yours, there was no blue and only green in Tick Tock. And the green was the EXACT color of the roofing bag left ...

Those are some strong statements. No blue?!




So I color sampled the original Tiktok video, no enhancements, just plain RGB sampling. Across multiple samples, I could not get a lower blue reading than green. I also sampled the rooftop bag in pic you posted above. It's also got quite some blue. Problem is, it's got even more green, but definitely not green as grass. What's more, the rooftop bag is exposed to daylight spectrum, while the garage debris is likely exposed to fluorescent light. Here is a link to the difference in typical spectrums for daylight vs fluorescent, not ironclad proof, but suggestive that garage lighting would accentuate green over blue. https://www.comsol.com/blogs/calculating-the-emiss...

Quote (warrenslo (Structural))

Also, your "hunch you think he was talking about" we are engineers we don't go off hunches - please provide evidence KCE is looking at this for your reasons. I provided evidence they would look at the penthouse, you haven't.

Allow me to transcribe parts of the Local10 news video to make this more apparent.

Kilsheimer says at 0:55, "(what) this says to me is the slab was poured as it was gonna be a roof"
Kilsheimer at 1:04, "you might run into waterproofing or roofing, that's a possibility, then we'll decide what we drill in the structural slab below"

Reporter Christina Vazquez at 1:38, "(Kilsheimer) is directing crews to drill into concrete, from a unit's balcony column, and floor"

The whole time the camera pans from Kilsheimer to his crew, who are at unit level, not on the roof, drilling in great weather. What should I infer?

• https://files.engineering.com/getfile.aspx?folder=f2e83e0e-a6f5-47bd-8112-6

Quote (arbitraria (Civil/Environmental))

I'm not sure if that's a genuine or artificial byproduct of the method of enhancement.

I think most of the deficiencies in image quality are attributable to the phone video camera. There aren't the commonly seen artifacts from high compression (low res) jpg formats. Now that's probably just from the fact that they were saved and copied for digital media (including) and how they are processed by this web site for display. A lot of factors potentially in the chain. I would hope whoever converted them (re-digitized) from the video frame captures used a non compression format such as TIFF with no compression option. Who knows? But I don't see major artifacts from file format compression. I just see a crappy phone camera trying to take a video under difficult low light conditions. But anyone trying to enhance the images should not in theory make them worse if they know what they are doing. They won't add artifacts per se. But they may unintentionally enhance "features" that were already artifacts in a poor image. So take it with a grain of salt. It's more likely that this web site adds artifacts by the way it resizes the images, but I have no idea how exactly they do it. Every time a jpg is resaved (vs copied) it adds artifacts. In fact jpg is not a good choice for this at all.

These threads remind me a lot of the Miami Bridge set of posts where in fact most of the issues were found within the first two or three sets before everyone one got a bit fixed on their own particular theories.

A few things have become clear though.

The security video which was there from the start seemed to show instant collapse. It is now clear that whatever first happened, it happened 10 to 15 minutes before the final dramatic collapse. So no - it looks like removal of one column alone did not bring the building down, but started a progressive collapse.

Going back to the Miami bridge collapse, it became clear that the bridge was giving out all sorts of warning signs for days that it was failing, slowly. Now there there was an initiation event (tightening the tendons), but in reality I think the bridge would still have collapsed on its own if left for another week. Same thing here but over a much longer period of inspections and deterioration of the concrete fabric of the building. The previous report recommending urgent work was THREE YEARS AGO. That's a long time for even more corrosion to occur.

There's a high possibility in my mind that this (that bridge would have fallen down eventually all on its own) is what happened here - i.e. for no apparent initiating reason, the pool deck finally failed. Maybe the standing water or planters got a bit full of water, maybe some one tapped the broken column, I don't think we'll ever know.

As for the roof stuff, again was it cause or effect? If the column(s) collapsed, did that initiate a partial collapse and cause things on the roof to fall off or vice versa?

So it would be much better here I think that rather than double up on everyone's pet theory, we stick to real known data ( of which we are almost certainly missing some vital elements not released) and structural issues and how to try and prevent this happening again.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

Just to add some fun to the color debate: That yellow sign on the garage gate in the tik tok video? It's not yellow but very dark green with white text. Phone cameras try to make odd lighting look "normal". Enhance that for tiny dim details and you get odd effects back in spades. The true colors of items in these images is not certain at all.

Oh, that's not the phone camera, it's sodium lighting. Green turns black and white becomes pale orange.

Quote (Auri (Bioengineer))

Oh, that's not the phone camera, it's sodium lighting.

You can probably get the white balance of the video camera off the white columns. If any assumption or guesstimate can be made about the paint hue you can gauge the blue shift and correct it if it is way off. I think. Maybe. For the sake of argument. That's assuming the same type of lighting is used throughout.
And then incidentally you would want to correct it to the daylight color temperature to compare it to the roof top photo. Most likely the video camera is set to fluorescent and the outdoor camera daylight. I'm a little hazy on color calibration right now. Every time I think I understand it I get corrected. photopic incandescent used to be 2856 kelvins. But the trend in imagery has been to make everything bluer than it really is. So I don't really know how to do it if it is even possible. Probably not.

Quote (SFCharlie)

July 12th at 2pm - Seeing widespread reports of street-flooding on social media all across Miami Beach and points northwards
Nop, no evidence of changing climate here...

Nope, no evidendce...
Two abandoned single story buildings in the industrial complex at my work had caved in some time over the weekend, likely from all the rain.


The geotechnical research into the foundation is needed. That land has gone from tidal pool to ocean/intercoastal crossing to filled in and building built. In newer ocean front construction, on the E and W of the property typically, steel cribbing sometimes gets driven down to form a wall to prevent waterflow from tides attempting to flow underground from the ocean to the intercoastal. Not common, but people are determined for their beachfront property. 2003 was the first time I saw that at a building located on the E side of the island.

We really like to move lakes/water ways, fill, and build on top down here, in under a month. Gotta get that ground filled in because the concrete trucks have been waiting since a month before the drawings were finalized.

Quote (dold)

6,000psi spec'd. Look at the left side of the column schedule on the original struct drawings.

Thank you.

Quote (NOLAscience)

Turn on captioning and go to Settings (gear icon) to select English translation. At about 8:50, he says that one column of the type that we are interested in would have
a capacity of 320 TONS. Impressive.
https://youtu.be/c-1wwF_STiY

EDIT TO ADD: This is a FANTASTIC video, and well worth the 30 minutes. It is so fast-paced; after the intro, the video is packed with information with technical ideas presented in a way that almost anyone can understand. He uses a very nice 3D model and even some cardboard mock-ups of different structural systems.

I think he has an error in his calculation of live load, which he calls "overload". 40 psf is 200 kilos/sq meter and he says (or the translation says) 300 ksm. Also, I don't see that he used any live load reduction, discussed on Thread 1 or Thread 2 of this forum discussion.

So 12x16=192
6000+28000=34000 (Yield point psi of carbon steel)
34000x192=6528000lbs (326.4tons)

Something aint right.

Precision guess work based on information provided by those of questionable knowledge

A building with no apparent preventative, successfully-deployed maintenance. Cosmetic attempts at best.

A poorly-drained plaza deck subjected to what over time was unmitigated water and chloride intrusion.

A two-way flat slab system inherently sensitive to direct punching, with tricky transfer of slab-column joint flexure that magnifies the punching effect... all occurring in what appear to be regions of much lighter-than-normal top reinforcement ratios. 

A very thin concrete slab (by today's prescriptive standards) susceptible to long-term creep effects made worse by a heavy paver and saturated planter system that is a very real permanent load.

If we were to design and construct a building with the above attributes today, how long do we give it before the confluence of systemic issues rear their ugly heads in the form of failure/collapse?  20 years?  30 years?  40 years?  And do we even need an acute, oddball event like faulty roof anchors or vehicular impact to set such a catastrophe in motion?

Some of the people who are married to the roof anchor theory don't seem to want to believe that the devastation absolutely could have been the result of a combination of unspectacular things at the pool deck level that got significantly worse over time. Ironically enough, it's that same thinking that allowed the building's condition to devolve the way it did.

I took that USA today video and stabilized it and cropped it down too.. and tossed the tiktok video onto the end of it so they're all in one clip. I also removed the bits where she scans around and it's too blurry to see into the garage, so just the good bits are left: https://youtu.be/LoNy55PaHlc

Someone in here earlier asked why I thought you could see sky when looking into the garage, and I think that USA today video has been overlooked a bit. You'll want to watch the video to get the full context and see how the shadows change, but in the first few seconds you can see this frame:


I actually didn't notice what was going on here entirely until I was fixing the video.. it's a very time consuming process and I end up looking at the video a lot during it. Anyways.. it seems like the pool deck slab is actually resting on a car parked in 39, and it's clear that you can see the column between 39 and 40 (not sure what the letter is, but it's between L and M and is 13.1).


I'm sorry to say it, but I'm pretty sure you guys have spent two days studying the greenish tint of the back wall of a garage.. it's clearly behind the car and in the very back. This roof theory really has no merit.

Seppe - I don't know enough about the structural stuff, but that looks good to me also. Will be interesting to see how many other buildings are like this in Miami and elsewhere.

As I said in an earlier post, I can see how it's difficult for anyone to say something is structurally unsound when it's still sitting there and has been for nearly 40 years. It probably takes something like this to focus the mind.

Everyone is so sure that the building didn't fall down for no reason or initiating event but so far nothing is standing out and maybe that's what happened - it just fell down, piece by piece which then accelerated. Just because it was built in the USA doesn't mean it can't just fall down if you don't maintain it.

If you had 8 re bars in a beam and you gradually cut then one by one, the beam would fail before you cut them all. Why does this not apply if they slowly corrode over time. At some point the FoS goes from 1.001 to 0.999 and that's the end of the beam / column / slab.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

The hardest question is how do you monitor a membrane that you cam not observe? Specifically, how do you actually protect the building envelope, when it is covered with pavers, asphalt and planters. I plead total ignorance to this issue, I really can't formulate a "best principle" for this problem.

Quote (Keith 1)

The hardest question is how do you monitor a membrane that you cam not observe? Specifically, how do you actually protect the building envelope, when it is covered with pavers, asphalt and planters. I plead total ignorance to this issue, I really can't formulate a "best principle" for this problem.

Good question - For starters, any detected leaking through a plaza system should raise a maintenance flag (the water has to go somewhere so a leak should be able to be detected and tenants are usually happy to complain about it).

The plazas I've detailed were effectively sloped roof membranes (hot applied asphalt is preferred) overlaid with a drainage board, then a slip sheet (to break the VQ/I shear interaction), and then a wearing surface (concrete for me or concrete with pavers). I could imagine some long term failures near the plaza drains, but otherwise think the system is fairly hardy. Repairing them is extremely expensive (requires concrete erasers) and locating the membrane leak will be frustrating. If the client doesn't want to invest in a 50 year life span system then they probably shouldn't be installing one.

If we can monitor the underside of 150,000bbl oil tanks for leaks, a pool and jacuzzi should be manageable. But someone will still need to make repairs once in awhile. That seems to be the real problem. That corrosion and permeability deterioration was observed, but apparently no action was taken.

Let's try not to tarnish the security guard here. We can't really be expecting to evacuate buildings every time we hear a thunderstorm like noise at 1:00am. And who would expect the building to come crashing down 5 or 10m later. There were probably too many people asking her what happened for her to leave her post and actually investigate. There also seem to be a lot of engineers here that wouldn't believe the building would actually collapse even if they themselves saw just one broken column anyway.

Really great work by 3DSoftwareDev and the analysis of the Ring video. It got me rethinking the initial collapse. I had always assumed the columns along link K and L collapsed first because that is what I saw on the CCTV collapse video. But I don't see how items can be falling to the right in the Ring video unless it's columns along line M that are failing first. I also assumed that M held firmly because column M-9.1 can still be seen in the Tik Tok video. But what if it's column M-9.1 between the 1st and 2nd floor that has failed? To go along with what 3DSoftwareDev mentioned, here's an elevation view of that scenario using the building elevations.

Quote (NOLAscience)

PLEASE STOP POSTING IN PART 5 PLEASE

SF Charlie
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Watch Live: Champlain Towers South Recovery - July 12
Right Now, and since at least 6:40 PDT (9:40 EST) the search team has been ripping up the pavers midway between the pool and guest parking. They are sawing holes in the pool deck and removing the slab with an excavator.


SF Charlie
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Quote (Jbourne8)

Thought I would put a frame from the TikTok video next to the USA Today video, both from Jbourne8's mashup. I thought they were the same file but they are clearly two different clips taken from two slightly different locations. Look at the #27 on the column and how the gate bars obscure it. Interesting how the object that resembles an AC compressor or patio table in the TT clip cannot be resolved in the UT clip. Of course this could be due to the greater compression in the latter. If there were 2 clips, I wonder: did she record more clips? Were the original files retained on her phone (likely will be higher quality and have less artifacts).



The same issue of compression/reproduction affects the other "primary" source of video evidence, the security camera from the property to the south. EVERYONE is working from a video recording of a screen that is playing back the video. I hope that the original video file is preserved (and that it becomes publicly available at some point), it is entirely possible that it contains sufficient detail to answer many questions, detail that was turned into blurry mush by the "re-recording". The strange "ghosting" of the highlights that can be seen on the white screen at the start, perhaps an artifact of the playback software, the screen, or of the camera performing the secondary recording, makes me think that much more detail is available than we are able to make out from the version we have access to.

Quote (Demented)

So 12x16=192
6000+28000=34000 (Yield point psi of carbon steel)
34000x192=6528000lbs (326.4tons)

Something aint right.

Did you watch the video? I didn't pay close attention to his calculations -- it was late when I watched and I may go back and watch again tonight -- but I thought he was using the design values for his calculations. He may have been comparing what the column was designed for to the load on it.

Quote (dold)

@waross,
I wouldnt go so far as to call our friend NOLAscience a "structural"...

Am I going to have to pull out those finite element matrix multiplications that I did BY HAND in graduate school to prove that I have structural analysis knowledge? Am I going to have to show you the shear flow calculations that I did yesterday for a job? No, I don't owe you such evidence.

I am just VERY suspicious of the stories people tell. I've seen too many 'neat stories' -- all tied up with a bow -- that later turn out to have had some crucial detail left out. I am not trying to blame any one person -- the failure was likely due to a combination of factors (see below) -- I am just trying to encourage us to look more closely at this man's statements and see if they ring true to you.

Quote (dold)

Ever since you've been active on this website, I suppose starting with the new orleans hardrock hotel collapse

I was active on this site BEFORE the Hard Rock Hotel collapse, see https://www.eng-tips.com/viewthread.cfm?qid=457407 . And, my account data displays, "After joining Eng-Tips Forums on November 20, 2017,..." In addition, I think I had an account before that but perhaps lost the login, so I may have created a new account in 2017. I've certainly been reading posts here for a very long time.

Quote (upstream)

Quote (rodface)
The “old” initial frame is a bug that turns out to be a great feature here. Question is, how old is it? Could it be from the last activation (minutes ago, hours ago, why did it activate, loud noises perhaps?), or is it from a few seconds prior?

Great feature/bug indeed. I was very thankful for that first frame - an incredible reference opportunity. I assumed it was from just prior to the first frame, but you're right, that's not proven.

I have a ring camera, and it creates a unique video for each event

SF Charlie
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Why isn't there more discussion teguci's sketches and notes? I find them quite convincing, especially (1) the planter hiding possible cracks in the slab step-up, (2) corrosion of #3 stirrups in this 'beam', (3) lack of development of rebar into 'beam' (no hooks, either), and (4) Champlain Towers NORTH (uncollapsed) has a different detail at this location (design flaw noticed and corrected?). My guess is that others find his theory convincing and have left the discussion. I wish I had had the patience to scroll through the design drawings to study the details.

Quote (teguci)

So I've fleshed out my completely speculative deterioration hypothesis. In short, the drop beam at the planters is not detailed to transfer positive moment across the beam even though the reinforcement suggests that it was designed as a 2-way slab (top bars match adjacent slabs top bars). It took 40 years because the #3 stirrups needed to deteriorate before failure started.

Questions that would serve to illuminate:
- Is there any rusting of the #3 bars at the slab drop beam?
- How far are the #5 hooked bars developed in the slabs at the transitions?
- Did they hook the "Beam A" bars into the columns?
https://files.engineering.com/getfile.aspx?folder=...

Does anyone have the plaza slab design details for Champlain Towers NORTH?

I wonder if water was pouring into the parking garage that night from the possible crack and/or failing slab at 11.1 below the planter? Has not been mentioned by garage witnesses, though.

Add this to the comments about the general lack of redundancy (due to lack of beams in this building, for the most part) by the architect at https://youtu.be/c-1wwF_STiY , and I think you have a cohesive theory of the collapse.

Quote (zebraso (Mechanical)13 Jul 21 06:39)

I don't want to joke about it either

I apologize.
(I guess I'm just trying to cope with my horror. Watching the videos on YouTube, sometimes I just burst into tears...)
Laughing is the way humans deal with pain.. (paraphrasing "Stranger in a strange land")

SF Charlie
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Quote (AutisticBez (Computer)13 Jul 21 06:43)

There could be a car under the debris right?

Watch: Yes, several, they have been being craned away.

SF Charlie
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Livestream is a great find @SFCharlie. Unfortunately the ramp area of primary interest is just obscured from view by the adjacent building!

They have cut a nice clean rectangle out of the pool slab by the column marked 39 (EDIT 38?), slab layers are visible, it's definitely resting on crushed cars at some height and there is a good amount of water down there.

Quote (1503-44)

Let's try not to tarnish the security guard here. We can't really be expecting to evacuate buildings every time we hear a thunderstorm like noise at 1:00am.

No one is "tarnish[ing] the security guard". This isn't "thunderstorm like noise"; the guard told Mrs Nir that there is "an earthquake". The guard COULD be trained to pull a fire alarm if there is an earthquake, especially at night, but this is "tarnishing" the security company that trained the guards, not the guard herself. Of course, earthquakes are not considered a risk in the Miami area. <<"We are not on a fault zone," said Dr. Warburton. "In fact, South Florida is what they call a-seismic, without earthquakes. It's one of the most earthquake free zones in the world. We are very unlikely in South Florida to suffer damage to an earthquake.">>

Some of the posters here are prone to exaggerating the comments they are responding to. Geez...

Quote (Auri (Bioengineer)13 Jul 21 08:38)

parts of the Local10 news video

Thanks for calling our attention to this.
Please, can you give us a link to the Local10 video?
Thanks

(Found it)
Structural expert studying still-standing Champlain Towers North looking for clues

I have a bit more experience than the security guard... If I would have been there, I would never have guessed the outcome... a recent collapse in China where about a dozen people were killed... almost expect that sort of problem in other countries... and the perps, real or imagined, will see swift justice... I would have never expected this in the US.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

The "Building Integrity" YouTube channel has posted a video analyzing the garage tour footage: https://youtu.be/ZAIJsaSo4Sw

Quote (rodface (Mechanical)13 Jul 21 15:02)

definitely resting on crushed cars at some height and there is a good amount of water down there.

Yep
I like to scroll the video back to earlier, to see what I've missed...

SF Charlie
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Quote (Jedidad (Computer)13 Jul 21 15:16)

The "Building Integrity" YouTube channel has posted a video analyzing the garage tour footage:

Thanks for the link!

SF Charlie
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Quote (SFCharlie (Computer) (OP) 13 Jul 21 15:01)

Watch: Yes, several, they have been being craned away.

Slavaging portions of deck, maybe columns next. Approx 10:30 a.m. edt

Note: L and M grid lines on perimeter wall.

Local10 video

“The police department has made the site a criminal investigation site and they have not yet given the right to do any of that sampling,” Kilsheimer explained.

So they are taking samples from the north complex for comparative purposes.

Collecting column samples. Approx 12:30 a.m. edt

Quote (warrenslo)

If the rebar was wrong this building would have fallen during construction or shortly thereafter.

Strongly disagree with this. It is entirely possible for rebar to be insufficient such that primary loads are supported without any problems, but reduced excess capacity in the initial construction creates an issue later after loading conditions change due to occupancy changes, corrosion, reduction of concrete sections, and other aging affects take place which can take years or decades to make themselves evident.

Just wanted to say: flipping through the plan set for the 40 year restoration... it's quite heartbreaking. So much work was going to be done, involving all manner of disciplines: structural, electrical, gas, fire, landscaping, architecture. It is silly to mourn the time lost in preparing those plans, an untold amount (most??) of design work never amounts to any real product or finished outcome, but there is just something about how this particular project came to an end, so unexpectedly, and so suddenly, with the deaths of so many, that makes reading these plans a moving experience.

from Youtube, also a local10 video

Salvaging vehicles from parkade. Entrance ramp wall visible behind.

Quote (rodface)

So much work was going to be done, involving all manner of disciplines: structural, electrical, gas, fire, landscaping, architecture.

Was any work to be done on the 'beam' at the 11" stepdown near Col Row 11.1? If not, and if the planter up against that change in elevation was to remain. then the building could have collapsed the day after the renovations were completed.

NOLAscience - the 40 year plans called for removal of the existing pavers and topping slab so the original concrete slab could be inspected for damage. The plans include several different types of repairs depending on the specific damage conditions uncovered and observed. From my experience, that's a pretty typical approach to concrete restoration since it's difficult to pinpoint every single crack that needs to be repaired especially in this case, before the topping is removed. Usually the contractor will get paid by an established unit rate for actual quantities of work, like $/linear foot or $/square foot for the repair type.

Quote (jbourne8 (Computer) 13 Jul 21 11:06)

Could you upload a copy of the USA Today video? Thanks.

Quote (“The police department has made the site a criminal investigation site and they have not yet given the right to do any of that sampling,” Kilsheimer explained.)

...but they can drop another building down on top; are they concerned about damaging a crime scene? Go figgure...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

There seems to be something missing in test core A. If you add up the depths of different materials in test core A, the result is 14-1/4". The picture taken by MC shows a test core that is 13" in depth. MC defines the top layer as 1-1/4" pavers on sand. I assume the pavers and sand were removed before coring and therefor would not be included in the picture of the core sample. So, if you add back the 1-1/4" pavers to the 13" core, you get 14-1/4". This leaves no room for the sand and makes me wonder how much sand does one need to lay out in order to install pavers over existing tile? According to the internet, you need 1 to 1-1/2" of sand to form a nice smooth bedding for pavers. Therefor there could be a layer of sand that is unaccounted for.

In addition, if the waterproofing had failed and there was 2-3" of rain in the days proceeding the collapse, the materials could have been saturated with water, adding to there dead load. Below I have calculated the approximate dead load for the stack of materials on top of the pool deck structural slab and have also included the weight of water absorbed by each material with rough estimates of absorption by weight.







WORST CASE: Pool deck loading according to test core A with additional 1.5" sand layer needed for paver installation and saturated materials.

1-1/4" pavers = (11psf/sf/in)x(1.25in/sf) x 1.06 (6% absorption) = 14.6 psf
1.5" sand layer = (120pcf) x (1.5/12ft/sf) x 1.06 (6% absorption) = 15.9 psf
1-3/8 tile and mortar = ((10psf) / (3/4in)) x 1.375in x 1.03 (6% absorption for mortar layer only) = 19.4 psf
2-1/8" concrete topping slab = (150 pcf) x (2.125/12) x 1.1 (10% absorption for ordinary concrete) = 29.2 psf
9-1/2" structural slab = (150 pcf) x (9.5/12) x .06 (6% absorption for commercial concrete) = 7.13 psf
TOTAL = 86.2 psf

From my experience it is reasonable to assume that the engineer designed the structural slab for 100 psf LL + self weight of the 9-1/2" slab and ignored the weight of the floor covering assuming it would just be 1 layer of tile or pavers like CTN. ASCE allows you to ignore the 15 psf load for partitions when designing for 100 psf LL, so ignoring 15-20
psf for the 1-3/8" layer of tile wouldn't be surprising.

The 2-1/8" layer of concrete topping is kind of a mystery also. The contractor could have built the 9-1/2" structural slab level, then poured a topping slab to build in the slopes required by the original 1979 architectural plans. The engineer might never have know about this extra 25-30 psf layer.

Therefor, the slab could have been permanently loaded to 80-90% of its allowable design load and could have been in this condition just prior to the collapse. If you add in deterioration due to chlorides, soft concrete, questionable design of connections used in this time period, and poor installation of required rebar over the column, then there doesn't necessarily need to be another event to start the collapse other than the slab to column connections finally gave out progressively undermining the stability of the exterior columns.

Hi all, long time reader and this is my first post here.

Mech engr, not structural, but have a good bit of experience with failure analysis, but mostly machinery.

Been reading as much as I can on this, and have come up with some tidbits:

1. The collapse video from neighbor building of course is a vid of a vid, and lacks very important earlier frames.
But one thing I think I see is a red-ish dust cloud hovering over the patio deck between the collapsing structure and the camera.
This may further corroborate the witness statements that the patio deck collapsed minutes in advance of the main structure. This seems to be supported by debris in the tik-tok garage ramp vid, but so hard to make out details in that dark area.

2. The architect (in the spanish language vid, well done by the way) seems to favor the theory that the collapsing patio deck put a lateral load on a few columns, especially near the heavy planter, possibly causing their buckling toward the failed patio deck.

3. The analysis of the ring cam vid from 711 is very well done and eye opening. It does seem to show the dimensional distortion of the room, as well as it rotating as a whole. Fits a column collapse from below.

4. The engr hired by the town (can't remember his name) has put out a request through the town to examine soil conditions supporting columns in similar structures. I doubt he would go in that direction this early without having a good reason. They may have enough rubble cleared to view the remnants of the first failed columns and whether they moved downward prior to or during the collapse.

So in my mind, seems two plausible theories at the fore: Patio deck failed first and put lateral load on columns, causing buckling.

Or column subsidence due to soil failure below. But why would this cause the patio deck failure minutes prior. Could, I suppose, if subsidence was a slow process.

Either could be compounded by construction or design errors.

Fortunately, the debris removal will soon (??) allow inspection of the critical bits and critical areas. How soon, figure in a matter of days/week.

And I think speculating on causes and piecing random bits is a healthy mental exercise for engrs, even if not in our field. It's how we learn how to parse through mountains of clues and pick out the important bits.

I can imagine the remaining video evidence, and there should be a good bit out there, has been gathered up by "powers that be" and will likely be kept out of public view for a good while. So that certainly frustrates us speculators.

They should already be doing inspections of failed slabs, columns and their attachments to look for design problems, missing reinforcement and can also do chemical and strength tests on the concrete. We probably won't hear much about that as with the hordes of lawyers involved, the engrs involved probably will not feel free to post things on sites like this or youtube.

I bet when the final debris removal exposes the first failed columns, you will see a tent set up over it to prevent vids taken by drones or the neighbor buildings. Under the guise of "weather protection". Wait for it!!

Being on the west coast, I'm just visiting now.

The third "video"(above), from way at the beginning of 6, has me puzzled.

The bar chairs in the background never move. The floor tips, in the video, up to 40% (21 degrees), and they don't slide or tip.

The floor reflects the bar chairs, so thus it is a smooth surface.

They are not fixed in place, as no one would do that and have an uneven spacing--this ain't Soho.


The stack of three boxes in the foreground: no movement there, either. And that's with a formerly vertical box adding its horizontal force.



Curious.


spsalso

For those who have not seen it, I wanted to bump this link to the full reserve study which was uploaded in the part 04 thread:

boo1 (Mechanical)10 Jul 21 12:53
Document with work to be preformed. Where is the major structural work?
https://files.engineering.com/getfile.aspx?folder=...

There are photographs of every conceivable major component, the original generator, the security system monitor (could help identify what sort of system was in use).

Quote (NOLAscience)

They are just there to observe the entrance and call 911 if a problem develops, such as intruders.

Dude, you're admitting yourself its not relevant, so...
Thank You.

The missing parapet is far more interesting.

Quote (spsalso)

I think the rotating clip was made to illustrate the scenario where "the dust always falls straight down" but of course does not hold 100% against other clues, such as those you have pointed out. It is likely that the dust is being affected by other forces. I like the idea that someone higher up mentioned, that the room's shifting out of square is pushing air around inside the space.

Spalso - or is that box empty (and the actual TV is to the left), so the empty box moves very easily?

As for the bar chairs, if the settlement is happening diagonally across the room from the right and to the front (towards columns M-9.1), then objects in the rear are less susceptible to movement. One possible explanation anyways.

I have no idea of the origin of your user name, NOLAscience, but it rings a chord with sparkies.
Nola Technology, Nola Devices, Nola Science; Nola Devices are marketed as a cost and energy saving device. While there are some very few niches that will benefit from a Nola Device, the great majority of the marketing is misleading and at times an outright scam.
To a sparky, Nola Science has no credibility.
Your user name is blowing a pretty loud dog whistle to the sparkies.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

CE3527-

Then the foreground would twist visually, compared to the background. The whole scene just twists evenly.

It's true the newly tilted box could be empty, and the stacked boxes full. Still seems like they would slide, though.


But, as rodface points out, it could just be an exercise in demonstrating the assumption of "vertical fall" for the "stuff". And that it didn't happen. Vertically.


spsalso

Quote (dik)

...but they can drop another building down on top; are they concerned about damaging a crime scene? Go figgure...

It would have been better for the investigation if they didn't have to do that, but we know that the lower 5 or 6 surviving slabs had partially or fully detached from E2 and E4, based on the way they were sagging. The lobby level slab had fully dropped away from those columns, based on the early video of firefighters in the basement. At the south end, 3 significant columns were both damaged and had lost bracing due to the surface parking deck dropping. The surviving section of tower was clearly badly compromised and at high risk of collapse.

Mark Loizeaux did a truly remarkable job bringing it down, specifically avoiding bringing it down "on top" of the collapse. With only a couple of days planning, he moved it SW as it dropped and still kept it within the site boundary and its own footprint. Yes, some evidence was lost, but not really in the original collapse area. They reported only dust fell on the geotextile covering the original pile.

It was a judgement call to bring it down, but it made a lot of sense to do it. Note also how the recovery process was able to move much quicker without the unstable remaining structure looming over them.

this is the detail in the Morabito rehab plans that shows strengthening of the slab to resist punching shear. These are preliminary plans so they don't say where they intended to use this but it looks like they didn't think some of the 9-1/2" slabs were adequate to resist the design loads for this failure mode.

Yep, if the deck and the stools are rotating and accelerating together, there is little reason for them to tip. We don't know really what motions were occurring.

Regarding the webcam video - some questions:
1. If the camera is accelerating down with gravity, how fast will other particles fall in comparison?
2. What is that powder and why is it detaching from it's substrate?
3. The upper floor is shearing to the right and the lower floor is shearing to the left (you can see this deformation has already happened at the entrance frame in the first second of the 11 second video).
4. Wasn't the elevator stair wall on grid M a clear dividing line between progressive collapses as seen in the exterior camera?

My thoughts - The white powder is being forcefully ejected due to structural deformations under considerable stress. Their direction and speed is not simply from gravity. The powder might be caused from the rebar in the slab above stretching (bottom slab in tension at upper left column to slab connection) and turning adjacent concrete into powder. You can kind of imagine the source of the powder is traveling to the right as the video progresses. As seen from the exterior camera, the floors are failing towards the column at K or L.

Further questions - do any of the particles arc up? Are particles traveling in different directions? Under gravity, 6th floor had a little more than 1 second in freefall. At what point do you think the building let loose in the video?

Quote (spsalso)

It's true the newly tilted box could be empty, and the stacked boxes full. Still seems like they would slide, though.

I read somewhere that Rosie, the owner of Unit 711 and the Ring camera, confirmed that the TV box that snaps/shifts midway through the video is indeed empty. I'm struggling to find it though. Will update this when I do.

I also find it odd that more objects are not sliding around during this time, other than the TV box moving. But perhaps the angle isn't quite extreme enough to overcome whatever friction the objects have with the floor, until the very end, when you can see surface the camera sits on moving to the right relative to the floor, which I assume is it sliding across the floor. I cannot tell what the camera is sitting on, if it's a piece of standalone furniture or some built-in casework. I'm assuming the former currently, but I don't know what the "column" in the very far left of the frame is, which seems to be attached to the surface below the camera. If it's a piece of furniture, it could be a credenza with a wood column supporting something above it.

Quote (Teguci)

2. What is that powder and why is it detaching from it's substrate?

I haven't seen a section through a typical unit, but I assumed these units were finished with a sheet of painted drywall at the ceiling, perhaps dropped down from the slab to hide plumbing and HVAC. But if it's actually the painted bottom of an exposed slab, then I'm wrong, and the powder would be from a cracking concrete slab above, which was suggested also. The particles seem lightweight and fine to me, suggesting drywall, but I'm not 100% sure.

I also think the camera is near the unit's balcony doors/windows, so there's not much behind the camera other than a thin section of slab, or the balcony above and behind. Perhaps the debris is caused by cracking of the slab or drywall near where the balcony connects to the rest of the slab. But it's unclear where exactly this debris is coming from, or how close to the slab edge it really is. The camera and whatever it's sitting on could be closer to the middle of the room, for all I know, hard to say for sure.

Sym P. le, NP. I attached the video from the USA today site to this post. It hasn't been edited at all from their version and it's just the raw video they had. It's 17M so it's quite a bit larger than the tiktok one was (1.59M).

Someone on youtube suggested this was a better video than the USA today copy, but it seems condensed to me and not as clear - https://www.youtube.com/watch?v=0g1sNRSOz44 You can also just download these directly from youtube btw.. but you'll have to google that one.

Also, people on youtube are also asking that we stop placing blame or investigating the victims. Lots of people are reading this, including friends and family members of the deceased. Try to keep that in mind, NOLAscience.

Teguci, I posted that ring video tilt in part 4 with the timestamp "9 Jul 21 08:33", but in that post I also added a bunch of parallel lines to the surveillance photo that show that the M column seems to be descending faster than the rest of the building. It is a hard angle to understand without drawing in what level should be though.

Lots of cameras and tables don't have as much grip as chairs do too btw, since they aren't really meant to shift around.. I don't think it's that odd that the chairs never move. And even an empty box would need a good deal of force from the building to shift like that on it's own.

• https://files.engineering.com/getfile.aspx?folder=1bcfb1e0-5d37-4614-a2ae-f

Quote (Teguci)

At what point do you think the building let loose in the video?

I'm under the impression that the building starts progressive collapse in the final 1-2 seconds of the video.

In the original footage, with audio, you can hear a terrifying rumbling begin right at the end before the power cuts out. It's also around this time that the floor and ceiling are doing a crazy dance and the whole room looks like it's deforming much more quickly.

https://twitter.com/_rosiesantana/status/140797089...

I always assumed this sound was the 5 floors above pancaking, but it could be the entire structure this side of the corridor sliding downward as part of the progressive collapse, as you seem to allude to.

Those chips/dust in that ring video seems to me to be way more then just some type of dust falling - something was either ripping/tearing, or being compressed so much that chips were being ejected (I lean towards this one).

Either way, it seems likely the chips are being ejected from their location? If that's the case, then it certainly seems possible that their ejected direction is shifting along with the wall. I think we can safely say the point of origin from the dust/chips is moving across the room (at roughly a foot a secondish?).

I think the left part of the floor is being separated from the ceiling (whether the floor is falling or the ceiling is raising I don't know), there's a crack propagating in the ceiling/against the wall behind the camera, and it's propagating like a zipper across the wall.


Can somebody confirm for me that the camera is roughly near the balcony looking in towards the kitchen? And somebody that's smarter then me confirm that if it was horizontal shearing we wouldn't have seen the crack propagate horizontally like we see in the video?

EDIT: Actually I think compression would be more likely to eject chips like this, can a civil/structure confirm this to?

I think its hard to equate relative movement on the particles once the building starts to move. Is the camera anchored to something and also moving? The vectors the dust takes will have gravity affecting it and whatever force knocked it loose initially. Whether those were localized shear, buckling or flexural failures, i could imagine dust being on a path not quite normal to gravity. The Gif maintaining verticality on the dust in my opinion isnt quite reality in terms of where the floor actually is relative to the horizontal plain. The first two gifs are great though. That 13 second frame change is really fascinating.

I've been looking at the video more.

I'm fairly confident the floor is higher on the left side then the right at the end of the video, I think by roughly 10deg as this is both the angle of the wall next to the refrigerator and the angle of the dust.


This is confusing to me though because if that's the case I would expect the dust to have gone from the right side to the left instead?

To those who have lost love ones and somehow find your way here -
May the Lord bless you and keep you
May the Lord make His face shine upon you and be gracious
May the Lord lift up His countenance upon you and give you Peace.

@Penagwin you are correct, there is a post higher up that marks it out, but yes near balcony, facing towards kitchen/front door/building hallway

@3DSoftwareDev are you able to create another GIF where you show the sped-up movement, but instead of looping the video, you play it forward, and then play it back? Imagine a simulation of a beam under load where the goal is to show it wiggling back and forth as it loads and unloads. Perhaps this allows us to better view the displacement without the jolt of it resetting to the 0 mark.

An observation after replaying the video with sound. At the beginning there is definite crashing and some groaning/rumbling. The groaning is similar to what is heard at the end, without the... for lack of a better term... galloping hooves sounds.

The most interesting thing to me is the empty TV box: at 0:10 there is a sudden snap/bang, and it shifts position.

Last night my wife's friend told her that their 1 year old had knocked over a floor length mirror that was leaning up against the wall. Just now I had the same thought about that TV box: What if there was a mirror, or a picture frame, that had been leaned against the wall, and then the TV box was placed in front of it. That sharp change in position marks the point where that leaned object became vertical, and then fell forward, against the TV box. What does this tell us about how this scene is angled?

Quote (Penagwin)

EDIT: Actually I think compression would be more likely to eject chips like this, can a civil/structure confirm this to?

Compression failure of concrete is typically "explosive". Not like fireball, but the dispersion of energy will send dust and concrete projectiles in all sorts of directions.

Quote (tmwaits1)

this is the detail in the Morabito rehab plans that shows strengthening of the slab to resist punching shear. These are preliminary plans so they don't say where they intended to use this but it looks like they didn't think some of the 9-1/2" slabs were adequate to resist the design loads for this failure mode.

I think you bring up a good point here. There's not really a code rationale for a structural engineer to 'strengthen' the shear capacity of an existing slab/column interface unless the design loads were being changed or the existing capacity was insufficient for the applied loads. Based on the core samples taken it appears as though the deck was a good bit thicker than predicted. I'd imagine their engineer elected to add in drop down panels to accommodate the existing loads.

Another thing that I'm a bit skeptical of are the planters. I might be missing it, but on my drawings I traditionally call out planters and their estimated weight of soil, etc. For really large planters on buildings, Ive put a line in there limiting the kind of plants they put in the planters. I dont really see that on the original plans.

Here is a video showing the "explosive" compressive failure of a concrete test cylinder:
https://youtu.be/iev2UNX16QA?t=62

SF Charlie - that was me that asked about the aerial shots. I’m assuming it’s a no-fly zone as well at this point.

Regardless of the reason, I think it lacks transparency. There is obviously something to be learned here, about both construction and government. Shielding it from view doesn’t sit well with me. Preventing trespassers, yes. Flyovers, no.

Quote (SFCharlie (Computer))

I apologize.
(I guess I'm just trying to cope with my horror.

No need to apologize. Please. I deserved it anyway. Healthy skepticism is what I would expect and I appreciate it. We're adults. As far as I can tell.

Quote (dauwerda)

Here is a video showing the "explosive" compressive failure of a concrete test cylinder:
https://youtu.be/iev2UNX16QA?t=62

Thanks! I guess that rules out compression then!

Quote (Js5180)

SF Charlie - that was me that asked about the aerial shots. I’m assuming it’s a no-fly zone as well at this point.

Indeed there is a NOTAM (FDC 1/3702) for "hazards", up to 3000ft centered on the collapse.

https://tfr.faa.gov/save_pages/detail_1_3702.html

Quote (rodface)

@3DSoftwareDev are you able to create another GIF where you show the sped-up movement, but instead of looping the video, you play it forward, and then play it back? Imagine a simulation of a beam under load where the goal is to show it wiggling back and forth as it loads and unloads. Perhaps this allows us to better view the displacement without the jolt of it resetting to the 0 mark.

Yes, good idea, I thought about doing this forward/backward version last night.

This is 4x speed, instead of 8x.

Quote (Rickytikitavi)

Another thing that I'm a bit skeptical of are the planters. I might be missing it, but on my drawings I traditionally call out planters and their estimated weight of soil, etc. For really large planters on buildings, Ive put a line in there limiting the kind of plants they put in the planters. I dont really see that on the original plans.

Yes, after 40 years a palm tree will probably weigh more than a bunch of ferns of equivalent weight at year zero.

I think the slanted falling debris inside the apartment indicates some sort of air movement or being projected in a certain direction, not rotation of the entire apartment (as others have alluded to) as there are other particles further inside the apartment that continue to fall "straight" down. This is indicated by the red arrows in the image below:

Some additional thoughts on Ring video, of the shifting camera table and particles falling. I'm in the camp of particles falling vertically versus changes due to air movement. Especially if these are concrete particles, more likely to fall straight down because they are heavier.

Quote (MechinNC (Mechanical)13 Jul 21 16:13

4. The engr hired by the town (can't remember his name) has put out a request through the town to examine soil conditions supporting columns in similar structures. I doubt he would go in that direction this early without having a good reason. They may have enough rubble cleared to view the remnants of the first failed columns and whether they moved downward prior to or during the collapse.

)

I agree that the hired engineer has seen something to indicate a possible geotechnical issue. Especially since the recommendation was for buildings east of Collins Ave. Also the timing of the recommendation raises suspicion. If he was just being overly cautious, why not make the recommendation for geotechnical investigations at nearby buildings several weeks ago? What prompted the announcement yesterday?

Does anyone know the model number or specs for this camera? Especially the focal length of this camera/lens, we can try to calculate/motion track the room _maybe_.

There might be other fixed landmarks in the video from the ring camera if looked at in reverse contrast or like a negative, since I didn’t even notice the granules from the ceiling in the mid-range until looking at still frames. Seeing a presumed 2d shape in the far wall and comparing it with other presumed 2d shapes could help to build out the 3D presumptions. Presumptively of course. I mean we can presume length of the back wall from the plans.

Quote (1503-44)

admitting yourself its not relevant

I'm saying what they have been trained to respond to -- in the past -- is not relevant. But if it feels like there has been a major earthquake or a plane has hit the building, I say the guards should be trained to pull the fire alarm.

Quote (CE3527)

the 40 year plans called for removal of the existing pavers and topping slab so the original concrete slab could be inspected for damage.

But would they remove the planters? The planter where the crack may have developed was under one of the very wide planters.

Pool deck underwent structural repair in 1996.
Link

Quote (waross)

I have no idea of the origin of your user name, NOLAscience, but it rings a chord with sparkies.

What are you talking about? I have never heard of Nola Devices.

There are some new docs on that property records site btw.

The permit for the 1996 waterproofing, which includes the pool deck repair, waterproofing the planters and fixing 20 sq feet of spalled concrete - https://uc1807f4ef13ea9781137ad7e1d0.dl.dropboxuse...#

And a blueprint that seems to be of the basement - https://uc18581952a2ac06dcb7ec8f3340.dl.dropboxuse...#

Quote (NOLAscience (Structural)13 Jul 21 21:22)

But would they remove the planters? The planter where the crack may have developed was under one of the very wide planters.

No. The planter walls were to remain. In hindsight, the walls should have come out to expose the whole deck. Probably trying to cut costs, but this would have been minimal cost in grand scheme of things. I guess it doesn't matter now.

Also, that 1996 waterproofing work looks like it's what prompted the lawsuit in 2001 from 112 over water leaks, since they're listed as the 3rd party defendants - https://www.scribd.com/document/512921705/Wall-Dam...

jbourne8, The links are not working.

spinspecdrt, oh strange.. they're on this site - https://surfside.one/public-records-search/

Labeled as "BLDG Concrete structural repair P#96-4403" and "Blue Print S1"

Just a thought on the debris reigning down in the ring video. Once the distortion of the slabs becomes evident the glass in the sliding balcony door would break allowing outside air to start moving around the apartment/room affecting the direction of concrete chips from the failing concrete. Top bars in the ceiling could be unzipping in tension in a fashion similar to other slab failures we have seen in the debris as the hinge forms.

Cutting slab around punchout column approx. 2:30 p.m. edt before storm break. I wonder if they will try to lift the whole section intact?

live Youtube link

Looking at a few possible camera specs, a 110 degree FOV appears to be the best fit, putting the camera about 36” from the left wall and 88” from the window. The room is 18x26, the kitchen is 10x16, the outside corner on the left wall is 18’ from the window wall, and the pillar on the right is about 21’ from the window wall.

Video of affected area post-cleanup at 0:49

https://youtu.be/jI6Up5Nv70c

Also, in my opinion, the groaning noise at the end of the video isn’t the building collapsing but rather the table sliding across the floor.

The initial collapsed building portion has been cleared to the garage slab. Entrance ramp visible on left and elevator shaft to right. (from Softee's link)

These look like the 4 #7 dowel bars for column L11.1 and M11.1. Not sure what if anything can be gleaned from that since we don't know what it looked like earlier in the debris removal process.

Earlier in the process at 1:30

https://youtu.be/fyCxzN1xpzU

Quote (rodface)

For those who have not seen it, I wanted to bump this link to the full reserve study which was uploaded in the part 04 thread:

boo1 (Mechanical)10 Jul 21 12:53
Document with work to be preformed. Where is the major structural work?
https://files.engineering.com/getfile.aspx?folder=...

There are photographs of every conceivable major component, the original generator, the security system monitor (could help identify what sort of system was in use).

Page 90 shows the security system views. If the recordings can be saved, there will be a lot of information in there.

Back to the punch out slab removal, they've cut it in half. It looks like they also may take the other half. Scratch that, they packed up and went home.

Quote (NOLAscience)

What are you talking about? I have never heard of Nola Devices.

Nola Technology is a valid technology for very very few applications.
If a 100 HP motor is driving a 100 HP load, there will be no advantage to a Nola Device.
If a 100 HP motor is driving a 10 HP load, there will be an advantage to a Nola Device.
It is almost always better and cheaper to use the correct size motor.
Where will a Nola device provide savings? A escalator in a subway station may be the best example. It runs 24/7 mostly at light load, but during train times at rush hour, it is working at full rated power.
A Nola Device will save energy when the escalator is running lightly loaded.
So what is the problem? Marketing. Almost all marketing for Nola Devices is a scam. Nola devices are touted as cost saving devices and sold for applications where the motor in question is working at or near full load and will not benefit from Nola Technology.
If you care (and I don't blame you if you don't care) look at this thread.
thread238-484643: How much better are voltage optimizers compared to a traditional capacitor bank and PF correction: How much better are voltage optimizers compared to a traditional capacitor bank and PF correction" target="_blank" rel="nofollow">
A quote from one of the leading electrical Gurus.

Quote (jraef)

jraef (Electrical)
29 Jun 21 18:06
I'm not going to sugar coat it. These things are scams.
Quote (Short article)
The concept is that if you can reduce the voltage supplied, then there will be reduction in your electricity bill.
Their opening statement right there is absolute unadulterated bovine excrement. Everything they say after that is their pathetic attempt to justify that initial stupid statement, so regardless if any sprinkling of truisms in there, the entire premise is false from the outset and designed only to extract money from your budget.

What happens a lot, and why they can get "testimonials" (assuming SOME of them are true) is that people approve spending money on these scams, then have to "justify" that by showing savings. But of course what's really happening is that because they NEED to show that, they ALSO implement other simple common sense actions, like turning things off when not in use, raising thermostat settings in summer or lowering them in winter, cutting back on everything, which cuts back on energy use, etc. Then at the end of the year they compare the energy bills and immediately attribute it to these scam devices that they foolishly invested in.

I should know, I used to sell one and was involved in what turned out to be a scam. In my defense, I NEVER told the guy that it was going to save him energy to use them, I was selling him Soft Starters for his cooling fans and they had the Nola circuit on them. But HE (plant maintenance mgr) was chasing a big bonus from his employer for "saving energy", so he submitted the energy bill savings and claimed it was because of the Nola Energy Saver in the Soft Starters that he bought from me. That was BS, the soft starters had bypass contactors so that Nola circuit never was engaged. They saved energy because they ran the fans less. It turned out that people left them running a lot more than necessary because of the old wives' tale that "It takes more energy to restart a fan than it does to leave it running for hours longer". That has NEVER been true, but the myth exists to this day. So when he put in the Soft Starters, he told the operators that it was now OK to turn the fans off when not in use, and THAT saved the energy. But he got his $60,000 bonus and retired. A year later I was called to the carpet because an audit was not showing any real change in the OPERATING energy of any individual motor when running with the Nola circuit engaged (compared to being in Bypass). Zero difference, because the fans were always fully LOADED when they were running.

Nola Devices are named after Frank Nola and are not related to New Orleans, Louisiana.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

Quote (NOLScience)

Did you watch the video? I didn't pay close attention to his calculations -- it was late when I watched and I may go back and watch again tonight -- but I thought he was using the design values for his calculations. He may have been comparing what the column was designed for to the load on it.

I did, but I have a hard time following subtitles that don't make grammatical sense at times.

It's been a long time since I've had to do any sort of maths on compression of a column, but I'm fairly certain it's more involved than the math done to get the total given.

Quote (NOLAScience)

Was any work to be done on the 'beam' at the 11" stepdown near Col Row 11.1? If not, and if the planter up against that change in elevation was to remain. then the building could have collapsed the day after the renovations were completed.

That entire section was due to be removed, inspected, and replaced as needed. There was a lot of language very specifically calling out replacing, not repairing.

Precision guess work based on information provided by those of questionable knowledge

Quote (NOLAScience)

But would they remove the planters? The planter where the crack may have developed was under one of the very wide planters.

Yes. The planters were cheaply thrown together CMU and painted. Nothing special about them. They've even been replaced, repaired, moved around over the years. Only a planter wall was to remain.

Quote (js5108)

Also, in my opinion, the groaning noise at the end of the video isn’t the building collapsing but rather the table sliding across the floor.

Thats the sound of steel screaming before it snaps. Tensioning up just like a guitar string and bang. I've been witness to many destructive load tests of steel. It's an earie moan that'll wake any iron worker from a coma.

Precision guess work based on information provided by those of questionable knowledge

Once again I call your attention to:
Watch Live: Champlain Towers South Recovery - July 12
where, if you slide back in time even a few tens of minutes, you will see one excavator passing cars to the left every rotation and the other excavator just taking huge chomps out of the pool deck. earlier in the day, the lighting was good enough to se the tail lights of a red car mid screen.
Study the days work.
Let us know what you catch.

SF Charlie
Eng-Tips.com Forum Policies

Quote (SFCharlie)

Once again I call your attention to:
Watch Live: Champlain Towers South Recovery - July 12
where, if you slide back in time even a few tens of minutes, you will see one excavator passing cars to the left every rotation and the other excavator just taking huge chomps out of the pool deck. earlier in the day, the lighting was good enough to se the tail lights of a red car mid screen.
Study the days work.
Let us know what you catch.

No need for the torch or saw. Just rip the rebar out.
Nevermind. Going on 4 minutes of trying to start a saw.

That slab has been crumbling though. Sections of it look like large chunks holding hands with powder.

Precision guess work based on information provided by those of questionable knowledge

Quote (waross (Electrical)13 Jul 21 17:08)

origin of your user name, NOLAscience

Have you tried Googling "NOLAscience"? NOLA is obviously New Orleans LouisiAna. science is just science.

SF Charlie
Eng-Tips.com Forum Policies

Taken from the recent video found by Softee at https://youtu.be/jI6Up5Nv70c:



Zooming in on the pile we get:


In the above close-up we see what appears to be an air conditioning unit from the penthouse roof surrounded by what looks like a ventilation fan, two parapet blocks, an anchor from the roof, and possibly the bottom of another anchor from the roof. There are probably a lot more parapet blocks under the pile, but one cannot be sure if just a few blocks fell or if the entire parapet fell. In the upper right there is another man-made object with sharp sides, but it is impossible to tell what it is. The following photo shows a close-up of the same pile from a slightly different angle.



In the above close-up we see what appears to be the same air conditioning unit from the penthouse roof with another air conditioning unit above it, with what looks to be a ventilation fan to the left of it, along with an anchor from the roof and the white arrows pointing to two parapet blocks. This time, however, we can see a hexagonal object with a pole protruding from it which may be the bottom of a deck table along with the mast for holding the sun shade. Again, at the upper right there is another man-made object with sharp sides, but it is impossible to tell what it is.

Looking at the same pile from 90° to the right, we see:


Zooming in on the pile again, we see the following closeup


In the above close-up, on the left at the top of the pile we see what appears to be the same air conditioning unit from the penthouse roof that we saw in the earlier close-ups. This time, however, it is clearly distinguishable. On the right hand side of the pile we can vaguely see more two man-made objects. The one on the top appears to be another air conditioning unit from the penthouse roof. The one at the bottom may be yet another air conditioning unit from the penthouse roof. The lightly colored rectangular frame lying over the bottom one may be the frame that held the two units when they were on top of the penthouse roof.

All of these units appear to be displaced from their original landing points on the floor of the parking basement because of the actions of the recovery crew that obviously cleared the basement floor. However, the fact that they have left the objects in this pile behind while clearing everything else appears to show that they believe these objects to have a special importance. So they are leaving them in place temporarily until someone else can inspect them.

What I infer from these objects being found on the floor of the parking basement and being left behind temporarily by the recovery crew is that these objects clearly fell from the penthouse roof before any buildings started to fall down and before the pool deck fell down. In other words, the falling of these objects from the penthouse roof was the trigger that started everything that followed, including punching a small hole in the deck, taking out one or two horizontal support beams between columns C27 and M11.1, which then caused column 27 to buckle, which probably caused the two adjacent columns to buckle also, bringing down the entire middle section of the buildings, then bringing down the other two sections of the building, and then causing the rest of the pool deck to collapse. These photos are as close as one gets to a confirmation of this general narrative.

Now we must determine why the penthouse roof fell down to start the entire sequence of events. This appears to be why Allyn Kilsheimer and his company KCE are taking cores from the penthouse and higher floors of Champlain Tower North.

Its possible the deck and planters just gave way one day. They reached a set limit in their capacity to remain intact. Call it a "tits up" moment.

Its also possible debris fell from penthouse. Fits the timing with work done. Its also possible the penthouse work caused deck planters to fail.

Its also possible for a sleepy driver to hit a stationary column. I don't think the columns had any chance of withstand -any- impact.

Why do you all enjoy looking at photographs and videos that were filmed on a potato? Ya'll need the 480i version. If you keep squinting really hard enough, Nessie is in there.




Hardly better images, but man, those aint A/C units. Why must the internet compress images more? Damn you.



One of my old MS&E professors told the lecture a joke one time.

A group of engineers take a taxi cab to a convention together. (yada yada yada filler)
As they're driving through some farm land, the taxi driver says to the engineers "Hey, look at that cow with one eye!"
The engineers all turned, covered an eye with a hand, and said "where?"



Precision guess work based on information provided by those of questionable knowledge

Quote (spinspecdrt)

I agree that the hired engineer has seen something to indicate a possible geotechnical issue. Especially since the recommendation was for buildings east of Collins Ave. Also the timing of the recommendation raises suspicion. If he was just being overly cautious, why not make the recommendation for geotechnical investigations at nearby buildings several weeks ago? What prompted the announcement yesterday?

Look on Surfside's document dump and read the entirety of "Properties East of Collins Avenue Structural Assessment Recommendations Letter". Geotech is just one of the areas they're investigating - the structural review looks to be incredibly thorough, there's a very detailed list of core samples they're asking for from each of these buildings. In addition to GPR for slab thickness and reinforcing layout, they want 3 slab cores for compressive strength testing and one more for chemical composition testing, plus a small core from a column. From the basement, first floor, third floor, highest floor, and roof. Among other site condition evaluations. That's one way to force the recertification issue, I suppose?

I'd guess they're seeing a multitude of potential environmental factors that are lending concern - subsidence, and maybe the effects of saltwater are proving to be more damaging in a shorter time span than originally anticipated? Perhaps the mixing concrete on-site with beach sand and/or seawater is looking less anecdotal, but a tangible concern for all these coastal buildings? (I'm in the northeast, I would have no clue, I'll defer to those of you with local experience on this one.)

I'm off to look at some screen caps of the video Softee linked, curious to see if the bent rebar at the base of the column remains give any more clarity to exactly how the building fell, since a good number of them look fairly distinctive. (That is if the mass of the collapse and subsequent debris removal didn't distort that evidence beyond usable observation...)

You know what the problem with safety is? Normies tend not to see issues. You need someone with autism super powers to imagine ways that buildings can collapse. Like, maybe buildings shouldn't have parking garages under them? I mean you are exposing building columns to terrorists and car drivers.

Maybe the columns should be super fat like the ones they use in Australia?

Quote (AutisitcBez)

Its possible the deck and planters just gave way one day. They reached a set limit in their capacity to remain intact. Call it a "tits up" moment.

Here's my "planter slab gave way" hypothesis. It's buried on the last thread, but here's a copy -

• https://files.engineering.com/getfile.aspx?folder=5b5b147d-7586-4f99-9739-8

It's odd that Linda March's body has not been reported as found. She resided in the PH4 penthouse. In theory she she should have been near the top of the pile.

Has anyone noticed if the order victims are being found is roughly tracking their floor number?

This document also looks new.. and has some info on the inspections up to the day before the collapse - https://uce471a6dbbe2994a0bb944b4c90.dl.dropboxuse...#

It's labeled as "INSPECTIONS REPORT FOR THE PERIOD OF 10-1-2019 TO 7-8-2021 FOR ALL TOWN PROPERTY" at https://surfside.one/public-records-search/

And wow.. you guys really don't want to let that roof first theory die. If you've been watching the live video for the last week they've been sifting that rubble around a lot and almost none of it is where it was on the pile btw. It seems like all of the objects they believe have an importance are being sprayed painted with some sort of tag (usually in blue or black), and are nearly always removed on the day they tag them. I've yet to see anything that was clearly from the roof get tagged.

Quote (arbitraria)

In addition to GPR for slab thickness and reinforcing layout, they want 3 slab cores for compressive strength testing and one more for chemical composition testing, plus a small core from a column.

Sort of a 'shotgun' approach, eh?

AtomixPro, you can see the order people have been found at this site. It seems like for the most part, the people in x4 apartments seem to be getting found last. Just step back in time to see how it's progressed - https://archive.is/OnsKD They do label Cassondra's apartment incorrectly, but the rest seems to be accurate.

Quote (apper.42)

Just a thought on the debris reigning down in the ring video. Once the distortion of the slabs becomes evident the glass in the sliding balcony door would break allowing outside air to start moving around the apartment/room affecting the direction of concrete chips from the failing concrete. Top bars in the ceiling could be unzipping in tension in a fashion similar to other slab failures we have seen in the debris as the hinge forms.

I don't know about this. If you watch the controlled demolition videos, many glass doors and windows stay unbroken as the building is falling, but are clearly deflecting during that time.

Wouldn't we also hear the glass shattering during the video since the slab distortion is getting worse? Unless the glass shattered before the video started.

I do think air movement is a possible explanation for the movement of the raining particles, but I just can't shake the feeling that it seems too controlled, consistent, and powerful - those particles are shifting direction with impressive unity. And if they are indeed from a concrete slab above, that density of small concrete chunks would seem to require a tremendous gust of consistent wind to knock them all out of natural gravitational vectors at an angle like that.

A new youtube video was added of the building too, it's very short and from February. It just shows the external parts of the building - https://www.youtube.com/watch?v=Ltw77weRymA

Quote (= MarkBoB2 (Electrical))

These photos are as close as one gets to a confirmation of this general narrative.

No way...

1. Those traffic cones are either 2.5 or 3 feet tall. A basic 3 ton AC condenser happens to be 2.5 - 3 feet wide, deep, and tall.

2. A condenser is mostly hollow. Dropping it 12 stories would probably dent it, and dropping a dozen concrete floors over it? Wouldn't be circular.

3. If they left AC units and roof anchors there, why did they take the roofing rolls and 6-8' bright green bag away?

Having watched many movies with computerized 3D visual effects I have to say that the animators generally lack an understanding of the physical world as their animations always have unnatural accelerations and such. If you're using unity and vectors in the same sentence we're right back in to the realm of metaphysics.

New video of the balconies was just released showing more wear on the balconies.




https://www.youtube.com/watch?v=Ltw77weRymA

• https://files.engineering.com/getfile.aspx?folder=6dbccdcf-27ee-4107-8cb3-3

Quote (MarkBoB2)

These photos are as close as one gets to a confirmation of this general narrative.

That’s more accurate than you think it is. But not in the way you think it is.

Quote (Teguci)

Here's my "planter slab gave way" hypothesis. It's buried on the last thread, but here's a copy

The “curb” at the front of the low planter seems to be an upset beam on 11.1 between L and M, similar, if not identical, to the ones at the west plaza drive planters.

Quote (TugboatEng)

If you're using unity and vectors in the same sentence we're right back in to the realm of metaphysics.

Hardly. Vector is a mathematical term, and I use it as such. I'm talking about physics, not metaphysics.

Quote (TugboatEng)

Having watched many movies with computerized 3D visual effects I have to say that the animators generally lack an understanding of the physical world as their animations always have unnatural accelerations and such

If this is some reference to what you think my background is, I'm formerly an architect. I've never been in animation. I'm pulling from my experience on many, many demolition sites (I'm actually quite fascinated by demolition) to know what concrete and drywall look like as they are pulverized and succumb to gravity. I'm only pointing out that concrete debris would require more air movement to cause what we're seeing than say, drywall/gyp board. So much so, that I wonder where enough air is coming from to cause it.

In my original post with 3 GIFs from the Ring video, I referred to tilting of a "refrigerator" - but I wasn't talking about the stainless steel refrigerator that is on the left near the doorway. Instead, I was referring to the tall, black shape on the right, behind the couch and chairs, which looked like the side of a refrigerator to me. But I don't know why the unit would have two fridges, so I'm not sure what this is. I've edited my original post.

Here's a cropped and zoomed version of the first frame-last frame GIF. Look at how the tall black object behind the couch moves. It's probably the second most active object in this sequence, other than the vertical wall/column between the doorway and the entry.


There's a column right there, so maybe the floor slab is buckling at that location, pushing the black object up But the black object is on the far side of the column line; I would expect the hinging to happen on this (camera) side of the column line.

This crop also better shows, I think, that the side of the room the closer to the camera is sinking relative to the kitchen.

Can you provide a non-cropped and zoomed version so we can see what is actually going on?

I notice there is a picture hanging on the kitchen wall (left side). We barely see it in side view. This gives us a clue about verticle as well.

Quote (TugboatEng)

Can you provide a non-cropped and zoomed version so we can see what is actually going on?

Did you miss the beginning of the thread? Scroll up. The uncropped versions are in my post at timestamp 13 Jul 21 03:59.

I can't seem to find a way to link to a specific post, or I would (is it possible?).

Here's the actual Twitter video, completely unaltered: https://twitter.com/_rosiesantana/status/140797089...

I created a slowed down version of the CCTV video and attached it this post. There are a couple of these on youtube but they seem to be re-transcoded so they aren't that good of quality. This one was slowed down by a factor of 4 and wasn't re-transcoded so it should be as close to the original as possible. Figured you guys might want to check this out too, since they're much easier to look at frame by frame locally than on youtube.

I'm going to go tinker around with that Ring video next.

• https://files.engineering.com/getfile.aspx?folder=d6e4d629-36d0-46e1-9e6c-d

Quote (Sym P. le)

I notice there is a picture hanging on the kitchen wall (left side). We barely see it in side view. This gives us a clue about verticle as well.

Good eye. If that is indeed a hanging picture, seems like it remains almost exactly vertical, so that does give weight to the theory that the room (or the camera) is not tilting, at least not as much as I illustrated in my 3rd original GIF.

Here's a copy of the ring video from twitter too btw, in case you guys want to mess around with the original locally.

• https://files.engineering.com/getfile.aspx?folder=a57846c9-8550-452b-a2d5-0

The hanging photos in the ring video seem like they're just getting pushed over by the wall.. and not everyone hangs photos with a regular hanger anymore btw. I only use wall velcro in my house, so my photos will never tilt. But that glass (of water?) on the counter is interesting.. seems to slide to the left at the start of the video, but seems almost level. Maybe this could also be caused by the shaking people reported?

EDIT: actually.. nevermind on the glass. It seems to just look that way because the table is already sliding a bit to the right at the start of the video.

Look at the fridge, too - it looks to be recessed into the wall. The gap at the top shifts, you can see how floor and wall started out orthogonal, end frame not so much. It looks like it's mostly the vertical members of that far wall being compressed to an angle much like the doorway column to the left, but probably some tilting of the floor plane as the structure is shifting into full collapse as well.

edit: There's a lot going on to the left, in looking at the frame on the wall, I noticed the cabinet (I think?) next to it, guessing over the sink. Check out the right vertical edge in relation to the fridge recess; also, the distance from the top to the ceiling is noticeably diminished.

Could the movement of the tall, black object on the right be due to the following?
- The floor slab has disconnected from the column
- The floor slab is falling while the column is not
- But the column still has some chunks of floor attached to it, which is creating the effect of the lifting/tilting the black object due to its proximity to the column, while the rest of the floor below it is falling

This would explain why there's no visible hinge/ridge in the floor slab between the camera and the kitchen, despite the evidence that the south side of the room has fallen relative to the kitchen (north side). Perhaps the whole floor flab has effectively "punched through" this column connection and is now sliding downward, more at the south than the north, as it continues to maintain rough planarity, just at an angle.

There is also a dark rectangular patch on the wall to the left of the fridge. The distance between the patch and the fridge closes several inches between the first and last frame. The floor definitely racks right to left vis a vis the wall/ceiling.

If one column line descended first, the cascade could step at each successive column line as the weak slab column interface lets go. The floor to ceiling height could be kept in check by cmu partitions.

For the CCTV footage from 87 Park I have found it simple to load, pause, and scrub the video from the original Twitter post. Works a little better on computer - i.e. mouse and a big screen - but a phone is manageable
https://twitter.com/wsvn/status/140805404680880537...

Doing this I have no problem identifying the PH roof parapet as well as PH balcony parapet falling without something substantial preceding them. The lights being on despite already falling 1-2 stories is because the front facade is falling ahead of the back, where the electric supply is coming from. The distinct shape of the west half of PH roof is clearly recognizable early in the fall as it tilts toward the viewer. For reference, daylight view of PH roof: https://gisweb.miamidade.gov/MDCPictometryIPA/pict...

I dont understand what relevance the ring video has, other than showing that the unit was on the verge of destruction at T-x. But we know that. Where are you guys hoping to take all of this video analysis? Seems like mucho work, poco value. Not to discredit the thought and work you all are doing, Maybe I just don't see where this path goes. We might be looking at gravity + acceleration particle vectors that don't have to point down. Without exterior visual references, in an aircraft, you can't tell if up is down, or down is left, right or up. Please explain.

I agree with the above somewhat.

Also appreciate the efforts , and it is useful, but lets not over analyse / obsess over it, or the Tiktok video. for that matter. Frankly trying to identify things in that one is ridiculous.. its blurry unidentifiable rubble at location x, end of story

would be really good to hear some opinions on the latest photos of the cleanup. Are they beams sitting in the water? east of the knee wall on ramp ?

In the 711 ring video.

There's two things we could be hearing in the beginning of the video. Could be the deck collapsing section by section, or columns progressively failing under compression one by one.

But it does appear that there's a large crash (which woke the camera and gives us the first indication of the room becoming a trapezoid) followed by a thump, thump, thump, thump, thump, thump, thumpthumpthump, thump, that seems to originate from the left and move closer to the microphone source.
Falling debris such as glass and concrete shards, and presumably things inside people's units, are also heard falling.
After the last thump which seems to be much closer and now more below, though still not audibly on the right hand side of the microphone.

Silence and debris stops falling

Snap, from all the way to the left, along with the swaying motion we see and metal groaning reappears, which could also be pipes reverberating. At the moment of this snap, if you watch the sink at the center of the video, it snaps up. I think at this moment we're in free fall. The source of this snap I believe could be where the collapsed section detached from the CMU at the upper level.

Shortly after, we hear the pancaking from below. 5 or 6 rapidly increasing in volume and pace radiate up from below on all sides.

I don't think the source of the thumping is the pool deck, as I believe that was already on the ground.
Close your eyes and listen. Just soak it all in on repeat.

We certainly can't see much, but there's as whole lot of directional sound.



Precision guess work based on information provided by those of questionable knowledge

That is a lot to make out of 12.5 seconds of mono sound... The initial movement of the empty TV box still puzzles me in light of all the slow building movements, and I can but speculate on the loud snap. I will point out there's likely a glass shelf in that corner of the living room before it goes to hallway & bedrooms... because 611 had that. Who knows what Rosie put up there. The support column L8 is behind that shelf, incidentally.

Say, aren't there 3 lights hanging off the kitchen ceiling? Spent all that time making GIFs and analyzing gravity & wall angles, missed an easy one.

Quote (Auri)

I agree. Careful step through the CCTV footage shows the rotation of the western PH parapet toward the viewer exposing the dark roof. A light in torn-open area of the surviving building near the machinery room show that the whole section has already dropped. You can count floors (as the guy did on the Spanish language video) and confirm the number of floor present. I also notice at around 03 seconds two ?columns emerging briefly unsupported from the rear of the rotating and falling roof.

Folks who "see" an AC unit in the garage TikTok haven't looked at a picture of where these units were at on the roof.

I found this video to have some the best detail (resolution) of some of the reinforcement that I could find.
Look at the concrete pool deck slab edge in the first screen capture...
.

.

.
Video Link: https://youtu.be/Mfelq1OnyBQ?t=47

Oldest scam in the books. Call for an inspection and then move the rebar to the north project and inspect it again.

Couple Ring video theories:

1) I still think the TV box movement is due to the room tilting slightly right, but another possibility is buckling somewhere in that wall, similar to what you see towards the front door. Buckling moves the box.

2) I think the appearance of the dark cabinet/fridge moving on the right is due to the camera sliding towards the right. The camera table pretty clearly slides to the right at the end of the video. So camera is getting a different line of sight on the cabinet/fridge as it move right.

Just observational, but in photos below you can see former column bases K-9.1, L-9.1, and M-9.1 from left to right. This is generally ground zero for the building collapse. M-9.1 is the standing column in the TikTok video. The rebar in the photo is the vertical rebar that anchored the columns to the foundation pile caps. They've probably removed what was left of the actual columns for forensics. Noted that the rebar in K-9.1 and M-9.1 look to be in pretty good shape while L-9.1 appears to have been obliterated.

Quote (jbourne8 (Computer))

AtomixPro, you can see the order people have been found at this site. It seems like for the most part, the people in x4 apartments seem to be getting found last. Just step back in time to see how it's progressed - https://archive.is/OnsKD They do label Cassondra's apartment incorrectly, but the rest seems to be accurate.

The archive link is to the New York Times floor chart. They don't list Cassondra at all, and they are correct about the occupants of 412. It seems that Cassondra moved last year, probably to unit 410 (marked unknown by the NYT). See this Reddit comment for details.

Quote (GPR_Tech (Civil/Environmental)14 Jul 21 12:05

I found this video to have some the best detail (resolution) of some of the reinforcement that I could find.

)

Looks like a construction joint. They made the key way but no dowels..... I saw some video of the south retaining wall that looked similar.

No dowels at all. It might actually be a slightly gapped expansion joint to accommodate left-right thermal movement. The upper surface separation appears straight enough. Maybe a shear key at best. In any case, there is no bar continuity across it.

Quote (23DSoftwareDev (Computer)14 Jul 21 05:35)

tall black object behind the couch moves

First Thank You
I also have a request; could you make a gif holding the bar and the stools fix?
I know this is not easy (I tried to line up all the frames of the FIU dash cam video to account for the vehicle movement). If the floor moved right, does the top of the black object remain stationary?

SF Charlie
Eng-Tips.com Forum Policies

It seems like a very realistic scenario for the collapse and one that has been well simulated in videos is that the pool deck slab failed in punching shear first and imparted a large lateral load to one of the main supporting columns (column M) of the building or if it didn't put a large lateral load on the column then it at least removed a key lateral support and doubled the unsupported length. I like this theory but there is one problem with it and that is the first column where failure occurred did not apparently fail in punching shear. The key to understanding this is the tic tok video which shows the column completely missing. I totally agree that this video is too blurry and low resolution to be certain of what the debris is but it does seem clear that the column is missing. If the initial failure was punching shear the column would almost certainly still be standing. Videos of the parking garage interior show the missing column painted white with a yellow band at the bottom just like the others and don't show any issues with this column that would indicate that it was over stressed.

the column

Thank you jbourne8 for your following comment:

It seems like all of the objects they believe have an importance are being sprayed painted with some sort of tag (usually in blue or black), and are nearly always removed on the day they tag them. I've yet to see anything that was clearly from the roof get tagged.

If you look at the photo below you can see that several shots of red spray paint can be found around one of the objects. I was wondering what this red coloring was, and now you have confirmed that objects of importance have been spray painted with some sort of tag before removal. This object must be considered to be one of importance. I believe that it is an air conditioning unit from the penthouse roof.

It is not a "problem" for the failure theory at all, if the first column did not fail in punching shear. Columns do not fail in punching shear. Slabs and plates fail in punching shear. Columns usually fail by combination of axial load and buckling flexure, especially if they lose lateral restraint provided by a slab. With one column buckled out, the adjacent columns would get an instant 1.5 x design load. With the slab no longer providing lateral restraint to any of them, they're most certainly going to buckle instantly, probably faster than the first column. The next columns then have 2.5 times their design load and no lateral support and so on. Actually there is no need for a failing slab to pull on the columns at all, but that certainly would not help the situation if they did.


Without a known scale reference, its hard to say, but those look kinda chunky to be from the parapet. Surely the parapet wasn't more than 6-8-12" max thick, no? I mean if that's a fan, OK it is circular shaped, from an AC compressor, those blocks must be at least 18" cubes or more..

Ok, here is a hypothesis which accounts for M11.1 being "missing". It can extend to include K11.1 and L11.1, if the evidence requires a similar failure mode for them. I'm not certain it is missing, in the blurry gloom of those video frames, but it's possible.

The pool deck fails in progressive punching shear somewhere south of 11.1, between the pool and surface parking, eventually forming a catenary between the southern boundary and the 11.1 columns. M11.1 stops the punching shear progression due to the additional beams there. Instead of breaking away from M11.1, the pull from the catenary breaks the beam and raised patio away from M9.1. M11.1 then fractures at the basement slab and is pulled over towards the deck collapse, assisted by the weight of the still-attached patio and beams as soon as it's off axis. This leaves M9.1 with catastrophic damage as the rebar for the beam is ripped away sideways, but not so much that it instantly collapses, and a 5 to 10 minute countdown is started for its failure.

Alternatively, the pool deck catenary pulls M11.1 away from the beam, folding the column over and leaving the beam unsupported at its south end. The beam hinges down on M9.1, doing catastrophic damage without instant collapse, before detaching and dropping to the basement slab with the patio.

The arrangement of beams there means you can broadly fit that hypothesis around any mix of KLM, 9.1, and 11.1; that you feel best fits the evidence. Add whatever corrosion theories you believe fit best, to weaken the joints as required.

Quote (MarkBoB2)

several shots of red spray paint can be found around one of the objects

I don't think that is red spray paint. It's too diffuse. Could it be Conduit Red in concrete, which is designed for coloring concrete used in utility work for proper identification, like this stuff: https://conspecmaterials.com/shop/concrete-colors/... ?

Quote (Murph9000)

and a 5 to 10 minute countdown is started for its failure

I like your theory. That's been rattling around in my head for the past couple of days, too, but I didn't put it into words like that.

What is your explanation for the 5 to 10 minutes between the failure into the garage and the building collapse. Why does the load redistribution take that long?

Also, the "blurry gloom of those video frames" is easier to interpret when you watch the original videos. The slight movement of the camera allows the mind to develop a more 3D imagery of the objects.

Exactly. Between loss of lateral support for columns, loads increasing on adjacents, possible lateral pull from failing slabs and ... corrosion, mayby excessive roof loads, there are more than enough bad actors there to fail any column. Nothing needs to fall from the roof or be hit by a car.

Hey. I'm new to this forum although I have read it for years and commented in the past under a user name I can't find...

I agree with the narrative that the terrace slab failed in punching shear and that initiated a progressive failure. I agree with posts above that the transfer beam at the slab elevation change may have failed in torsion, or may have released from the support columns due to the offset lateral loads from the catenary response of the failed terrace. Seems plausible. This beam failure may have provided a bit of time before total punching shear failure of other elements.

What continues to bother me is "why now?" What was the trigger event? It just seems too coincidental that work had begun just shortly before total collapse.

Did something impact the terrace slab from a partial failure of the upper roof cantilevers due to construction activity? Possible. Is it possible that the upper parking area supported a construction staging vehicle or heavily loaded truck the day before? Maybe this loading caused a failure that took some time or additional factor (thermal expansion water discharge ...)to manifest into a collapse? Perhaps the failure was hidden below the sand and pavers (I've witnessed this myself).

As a structural engineer I've worried many nights about potential for structural collapse and, especially, progressive collapses. I'm just a one man firm in a small resort area. But, in my limited experience, I have been involved in the shoring and redesign of a dozen structures that were nearing a collapse failure(column degredation, progressive joist failure, wall collapses due to excavation, deck pull out etc.) Each of these conditions was life threatening. In the case of the progressive joist failure, seventy five people may have been involved.

Sometimes s__t happens. Maybe the truck hauling the roofing material or the grout for a facade takes a wrong turn and ends up where it shouldn't. This happened on a project of mine where about to they use a residential elevated slab as a construction staging area. I caught it as they were backing a 20000 lb trailer onto the structure. I wouldn't expect a building official to catch that even though my plans did not allow staging on that structure. Had my slab broken, though, the remaining structure would have been fine because I designed the building to isolate failure areas.

We have some control over what happens within a building. But, open air, exterior terraces that load up structures supporting multiple floors maybe should be evaluated with additional care. I often separate the structure to reduce potential for water intrusion and thermal effects transferring to interior spaces. I wonder if this needs to be something the code addresses directly?

Theoretically the steel should start stretching and take (allow) some small amount of time for deflections to form and secondary stresses to appear. Since the steel is designed to yield before the concrete reaches compressive failure levels, the concrete is actually failing from the added secondary stresses.

Quote (NOLAscience)

I don't think that is red spray paint. It's too diffuse. Could it be Conduit Red in concrete, which is designed for coloring concrete used in utility work for proper identification, like this stuff: https://conspecmaterials.com/shop/concrete-colors/... ?

Then why is the rebar above it colored red as well?

Quote (MarkBoB2)

If you look at the photo below you can see that several shots of red spray paint can be found around one of the objects. I was wondering what this red coloring was, and now you have confirmed that objects of importance have been spray painted with some sort of tag before removal. This object must be considered to be one of importance. I believe that it is an air conditioning unit from the penthouse roof.

A smudge of red on a pile of garbage.

No red on the “anchor”, “parapet blocks”, or “roof ventilation fan”.

No cones. No caution tape.

You’re doing more to undermine your “theory” than to support it.

I happen to think that that red smudge is the remains of someone’s oversized sock puppet.

Quote (MarkBoB2)

I was wondering what this red coloring was

Since it’s still a USR Triage site, red indicates HR location.

Quote (NOLAscience)

What is your explanation for the 5 to 10 minutes between the failure into the garage and the building collapse. Why does the load redistribution take that long?

If the beams pull away from KLM9.1 just right, they potentially shatter the concrete inside the column's rebar cage over essentially anything up to the height of the beam. Hypothetically, the rebar for the beams ripping out both shatters them and empties out the rebar cage a little. That critically weakens the column, but it still has the heavy vertical rebar and some concrete remaining to provide some support and the building attempts to redistribute loads. The failure then radiates outwards from there, with neighboring stress points cracking and deforming under overload, until enough of the structure has lost margin that it goes into rapid collapse on the next big crack.

RC columns can survive a surprisingly long time under heavy overload before they finally give up. See the Hotel New World in Singapore, where the slow phase of failure took years.

I don't have time to do a full writeup at this point, hopefully later today. But I invite any of the video-pixel-peepers to revisit the CCTV from the condo to the south:

-SLOWLY scrub back and forth from 0:00 to 0:06 in the video, the beginning of the visible collapse.
-Note that the two arc flashes between the collapsed portion and the standing portion are the first frame of the clip.
-Note how the flashes don't correctly line up with the lights going out in the windows to the right.
-Note how the two windows right in the middle seem to stay lit up for a very long time after the flashes, once they seem to have moved more than 1-2 stories.
-Now I invite you to consider the following: those are not lights; they are reflections from lights across from the windows.
-Watch how tiny "lights" appear to turn on and off as the facade slides downwards. Notice that the sequence appears to match the movement of the building. Perhaps what looks like lights turned on is nothing but reflections.

What does this mean? Perhaps nothing. Just interesting.

For what it's worth, that mush doesn't look like it includes the penthouse parapet in the collapsed section :O

Edit: Well I don't know if it's there in its entirety or not, but the upper two parapets are clearly visible at the top of the falling facade:

There is some creative photo "analysis" in these threads.

I mean, we're looking at a pile of mangled demolition debris, and we've got posters stating that the unidentifiables therein are, beyond a shadow of a doubt, proof of a roof-level failure as the source of the collapse.

Sprinkle in some "PROVE ME WRONG" vitriol, and it becomes clear that a couple folks are going to believe what they want to believe about this collapse, and their belief is limited to some sort of Rube Goldberg roof-level chain of events.

Re: Penagwin (Computer)14 Jul 21 04:49
New video of the balconies was just released showing more wear on the balconies.

I'm no SE, but it seems like there're an awful lot of pictures where the rebar is really close to the bottom. Did they design it that way to make the slab as thin as possible or is it a construction error, or a combination of both?

@john2025 one thing to keep in mind is that concrete spalling had been noted and was in the process of being addressed. There is one document (can't remember which) that describes the contractor actually having chipped away spalled concrete. I believe this explained the apparently terrible condition of the pool room ceiling; it had already been chipped away. Perhaps that is what we are seeing here, they were chipping away all damage all over the building before going in and patching. Not sure if this is standard or best practice for concrete repair.

If I may offer a slight correction.

The slab bars may pull out some concrete from the columns with them at that connection point. That concrete fails from tension.

Column bars do not rip out. The column's concrete compressive failure is violent and blows the bars apart and away as the concrete explodes outward. That most likely occurs at the point of maximum flexure from the secondary bending moment, typically at column mid height, brought about by the buckling displacement x axial load, which in combination with the axial compressive stress exceeds the compressive strength of the concrete and it shatters.

Quote (MaudSTL)

I think that Cassondra Stratton lived in 412, not 410, based on an evaluation of her recent blog photos, which show her in a unit that she just redecorated at great expense.

If I'm not mistaken, the particular post you're citing is from 2017. Her blog design is irritating in its clumsy navigation, but if you're looking at one of her entries, you can hover on the main image and see white arrows to the sides, which is the only place there seems to be a date.

I've seen it mentioned elsewhere that her most recent posts (not on the blog, probably Instagram) show a different unit that corresponds with the layout of a x10 unit.

It would be nice if we could take the non-engineering related subjects back to Twitter, or wherever they belong. It sure isn't here.

Thanks so much

Quote (Murph 9000 (Computer) 14 Jul 21 15:53 Ok, here is a hypothesis which accounts for M11.1 being "missing". It can extend to include K11.1 and L11.1, if the evidence requires a similar failure mode for them. I'm not certain it is missing, in the blurry gloom of those video frames, but it's possible. The pool deck fails in progressive punching shear somewhere south of 11.1, between the pool and surface parking, eventually forming a catenary between the southern boundary and the 11.1 columns. M11.1 stops the punching shear progression due to the additional beams there. Instead of breaking away from M11.1, the pull from the catenary breaks the beam and raised patio away from M9.1. M11.1 then fractures at the basement slab and is pulled over towards the deck collapse, assisted by the weight of the still-attached patio and beams as soon as it's off axis. This leaves M9.1 with catastrophic damage as the rebar for the beam is ripped away sideways, but not so much that it instantly collapses, and a 5 to 10 minute countdown is started for its failure. Alternatively, the pool deck catenary pulls M11.1 away from the beam, folding the column over and leaving the beam unsupported at its south end. The beam hinges down on M9.1, doing catastrophic damage without instant collapse, before detaching and dropping to the basement slab with the patio. The arrangement of beams there means you can broadly fit that hypothesis around any mix of KLM, 9.1, and 11.1; that you feel best fits the evidence. Add whatever corrosion theories you believe fit best, to weaken the joints as required. )

I appreciate your post. We are trying to walk a fine line between being skeptical of new theories but also open minded if the evidence points in a new direction. I think we are at that point with what, to my eyes, shows the pool deck area column basically destroyed prior to the main collapse. Your theory about the catenary action of the progressively failing slab pulling the column over may be 100% correct. I feel like another plausible explanation is that a section of the roof fell down the facade of the building and impacted directly on top of this column. Looking at the first second of the video from next door and comparing it to a shot showing the existing roofline looks like prior to the main collapse, a section of the parapet is missing. Let me reiterate that I am not wedded to any particular theory. I want to look at the evidence we have (however imperfect that may be) and form the most reasonable hypothesis on why the collapse occurred. I also think the original design was probably flawed in many ways and was a major contributing factor.

Rodface,

The reflection theory is interesting and I’ll have to take a look. It does appear that that particular “light” gets tucked under, which would be consistent with a reflection.

I did notice that the red light on the top of the elevator room, which I assume is an aid to navigation light for airplanes, is on a circuit with a white light to the far right of the eastern wing.

As for the parapet, I don’t think there’s any question most of it was there, but in the earliest frame, it’s hard to line up. Try drawing the same lines in that frame.

My theory is that the upper roof collapsed before the main collapse, by as little as a few seconds or as much as 15 minutes. It could be a trigger or a result of shifting elsewhere.

And Allyn isn’t drilling that roof slab for nothing. I’m not going to say that a washing machine fell off the roof and brought the pool deck down, but I do see it as a weak link that could have contributed to the collapse.

One other point - in most pics, the rebar looks relatively clean. However, the ramp column, which I think would be M8, looks really bad.

We should be seeing some evidence of the missing parapet theory come to light very soon, if not already. As I said above, the last photo with a supposed parapet looked a bit beefy for a parapet. Its basically not a load carrying member and most likely not more than 8" thick. Has anyone seen that piece dimensioned in a design drawing anywhere.

I think that theory might be getting less probable by the minute.

I'm kind of a stereoscopic photo fan. When I first saw that video, I lined adjacent frames together to view a stereoscopic image in a 3D type viewing perspective. Since many things are moving downwards, rotate them 90° to the right, to minimize the appearance of 3D displacement in depth from the downward motion and it helps. Those lights did seem to have a reflection characteristic, as they seemed to be a bit in front of the action, rather than from behind. Another thing was that I believe the camera was swaying from the seismic vibrations, as one duo of pictures will appear to be displaced a bit forward from their adjacent pairs. These don't take a lot of motion to distort depth. Anyway I was impressed as to the apparent depth of the hole that opened up below what seemed to be the roof, or a good portion of it, that I thought it looked like it was trying very hard to remain horizontal. Well, if you like that potential method of seeing some depth there, I thought it was interesting for awhile.

Quote (MaudSTL (Computer))

I think that Cassondra Stratton lived in 412, not 410, based on an evaluation of her recent blog photos, which show her in a unit that she just redecorated at great expense.

Cassondra previously lived in 412, but moved within the building last year, probably to 410. She blogged extensively about the first place, but not so much about the move. The reddit thread I linked has more details.

Quote (Murph 9000 (Computer)14 Jul 21 15:53)

Ok, here is a hypothesis which accounts for M11.1 being "missing". It can extend to include K11.1 and L11.1, if the evidence requires a similar failure mode for them.

Murph - In agreement with your post, just a minor clarification. We do know what happened to K11.1. It failed in punch through and can still be seen in the post collapse photos. But I agree that L11.1 and M11.1 may have failed differently (together or separate). One difference between patio support beam at L and M, versus K is that the raised patio extended further from the building than along line K. That would suggest to me that these beams had better capacity to resist bending than beam along K. This could have accounted for a different failure mode

Whatever was left of L11.1 and M11.1, whether they were destroyed before the building collapse or not, was buried under the rubble. I'm sure they got heavy scrutiny during the cleanup.

Quote (1503-44 (Petroleum) 14 Jul 21 17:37 We should be seeing some evidence of the missing parapet theory come to light very soon, if not already. As I said above, the last photo with a supposed parapet looked a bit beefy for a parapet. Its basically not a load carrying member and most likely not more than 8" thick. Has anyone seen that piece dimensioned in a design drawing anywhere. I think that theory might be getting less probable by the minute.)

The 4 ft tall parapet is comprised of reinforced concrete columns at 20 o.c. with a reinforced concrete cap beam and CMU wall filling in between the columns. Maybe there are some other notes or details in the plans but this only states that the column is tied to the slab with 4 -#5 bars.

Quote (1503-44 (Petroleum))

It would be nice if we could take the non-engineering related subjects back to Twitter, or wherever they belong. It sure isn't here.

If you're complaining about Cassondra, she was a witness to the patio deck collapse so her location at the time she saw it is relevant.

Question for the guys who build buildings: If I am not mistaken the objects circled in green are the scuppers that drain from behind the parapets. But what are the items circled in red? This is from the Google StreetView of 87th street looking up at the top of the façade that came down first.



Edit with a W.A.G. - condensate drains embedded in the floor slab? That they chipped out when they built the penthouse?

Just found another video I haven't seen mentioned, it's from a video of a Hurricane Wilma in 2005.

https://www.youtube.com/watch?v=X4BwnI0VyPM

Around the 3:30 mark there appears to be a shot of the pool/patio deck and it looks rather torn up. Can any structure/civil engi tell if this is cosmetic or if it would have prompted repairs, etc? It looks pretty bad to me.

@Penagwin great find. That's the toppled wall between the pool and 87th street to the south of the building.

Quote (rodface )

the objects circled in green are the scuppers that drain from behind the parapets. But what are the items circled in red?

Green are the overflow scuppers, red is balcony drainage (added in 20xx)

Quote (Penagwin (Computer)14 Jul 21 18:29

Just found another video I haven't seen mentioned, it's from a video of a Hurricane Wilma in 2005

)

Ungrouted CMU wall. I don't see any rebar. It wouldn't take much to blow that over.

@Santos81 interesting. I would have thought that the scupper sufficed as a balcony drain, but perhaps it ended up too high or too far off to the side? Though if I entertain wild thoughts without enough evidence... if the drain on the RHS was inadequate, and water was flowing/pooling to the LHS enough that additional drains were needed... could that be indicative of slight settling beneath those drains? To carry that thread further: is the balcony itself sagging, or is the building somewhere below descending by 2mm?

Quote (rodface)

I would have thought that the scupper sufficed as a balcony drain, but perhaps it ended up too high or too far off to the side? Though if I entertain wild thoughts without enough evidence... if the drain on the RHS was inadequate, and water was flowing/pooling to the LHS enough that additional drains were needed... could that be indicative of slight settling beneath those drains? To carry that thread further: is the balcony itself sagging, or is the building somewhere below descending by 2mm?

The overflow scuppers were not the primary RW drainage outlets for the roof or UPH parapet balcony. Their base elevation was 7” above TOS and incorporate spring loaded doors. It would take approx 10” of water before they will open and it’s not subtle. Definitely wouldn’t want to be standing under one when it does. In Miami, Flat Roof systems utilizing scuppers as primary RW discharge to ground on Mid-Rise and greater structures require downspouts. I marked the original balcony drain on your photo. For the given drainage area, one outlet definitely was not sufficient and interior flooding would occur before the overflow would be reached.

I edited the Ring video to have a more realistic (but very hypothetical) tilt, and tried to end it with the least tilt possible to cause the table and camera to slide across the table/floor like they did. This really doesn't capture how much the room is leaning towards the camera by the end, but that's impossible to illustrate in this video. I then compared it to the CCTV footage in the second half of this video. I think the rushing sound in the Ring video is the upper floors collapsing, and more than anything this illustrates how long the building had been falling apart before the CCTV footage begins. I placed it where I did too because we probably only lost around 100ms when the power cut out to that area. Warning you now though, this is a pretty horrifying version of this video. https://youtu.be/8FNkJrHPBKQ

Mostly I think this video shows how weak the roof theory is, since it hinges entirely with this CCTV footage that begins way too late to be that helpful. I also had an AC unit that fell off my building once and down 4 stories, and it wasn't exactly square shaped anymore when it was picked up off the sidewalk. They aren't constructed that well, and I really doubt they'd be identifiable in the tiktok video. I think if this was as simple as the roof causing the collapse they would have announced it by now and wouldn't be panic inspecting and closing old buildings in Miami too.. a chunk of parapet at the bottom of the pile shouldn't be hard to find. It also doesn't really match up with the statements from people at the collapse.

@Santos81 Got it. Those figures surprise me. Does that mean that a flat roof equipped with a parapet and scuppers as described would collect and hold a considerable amount of water before it was able to drain through those devices? I am somewhat ignorant on the subject, but I have to assume that the roof would be designed to shift the water to some other means of collection/discharge and would not be designed with the expectation that it would regularly hold up to several inches of accumulated rainfall?

@jbourne8 this edit somehow makes the scene appear very realistic.

Generally one would expect roof sloping to centralised catchment points and drain pipes from those to ground level. Only runoff from the balconies would normally be directed outward and overboard.

The anchorage of the parapet looks like it is sufficient, if it was in good condition. A column at 20" o.c. and the top tie beam would be all that I would expect, if that much. The dimension of 8" thickness was exactly what I expected. I'd say, if in good condition, it needed quite a bit of help to get knocked off the roof.

So to see that on the ground, we look for 8"x8"x16" CMU bits with some sand-cement morter columns on each end. The columns cannot be more than 4" wide and they have only one 16" long block between them. Anything else would put the columns at > 20"c/c. So, probably adequate, or more so, but probably not very chunky when broken into pieces. The cap beam would most likely form the largest remains of that assembly.

I have found it almost impossible to find images or video of the Western exposure/Front of the building post collapse. There are some aerials but they are mostly focused on the eastern side and rarely get low enough to view the Drive Thru Lobby area. After much footage scrutiny I finally found 2 that had such vantage points. It seems like they were keeping everyone away from the front of that condo at street-level, and rushed to demolish it asap.

I wanted to find this angle because several survivors that did go down the stairs all the way to the basement, they mention flooding and that the roof or ceiling was crumbling down..this causing some to return back up the stairs and to balconies.

Here are a few stills I grabbed from videos and as someone else mentioned above, here we go analyzing crap photos.... Actually I want y'all to analyze them and tell me what you see.

Zoom in, what is going on with the drive thru overlay?
Link
Link

From a different angle, I've circled a few things, one is a ladder...but why is it braced between the truck and planter? (I've wondered if that truck backed up too far and bumped the retaining wall). But beyond that what are the other items?
Link
Link

Optical98 - I wondered about the stories of people going from the upper floors to the basement (instead of via the lobby) as well. A review of the floor plans shows that the stairwell didn't have an inside lobby level exit. The lobby level exit was instead on the side of the collapsed pool deck. The exit door is blocked by debris in the photos. It seems really silly that if you park your car and want to go straight to the lobby you have go up, go outside on the pool deck, and then back in (or take the elevator). Apparently that's the way it was. While the stairs remained open, it seems that the people "trapped" on the balconies were the ones that feared going through the garage. One of them mentioned fear of electrocution in the standing water, which would have been a legit concern.

The 911 calls from the survivors were released btw - https://www.youtube.com/watch?v=-V82BZuV-m4

Does anybody have any theories on this concrete slab in the post-debris removal photo? It appears to be fairly in tact in areas where it's exposed. I thought initially this was the garage slab on grade and they just removed the rest of the garage slab on grade around it which became filled with standing water. But I don't think there's any reason for them to remove the garage slab on grade, or that place becomes a mudhole plus I haven't seen it removed in any pictures. Then I thought maybe it's the pool deck from above, but A) it doesn't have pavers on it and B) this is the exact area in the Tik Tok video where it seems to show concrete chunks to have fallen, so how would this be in one neat piece?

Maybe the answer is obvious, but it's escaping me.

I haven't figured out how to reply to people on here yet, Odds n Ends --

Someone asked where the Storage Areas were at:

Link


Marked area on Ramp, they drew(sprayed) a red rectangle and placed cones about it.

Link

This is a tough read, it's from an article regarding the Mother and Daughter (Unit 904) that fell but have survived thankfully (Prayers for a speedy recovery for both of them)!
I'm posting it because in their accounting of events, they did not drop all the way down at once, there were seconds between the floors dropping... 9th dropped to 8th, paused briefly, then down to the 3rd floor.

Link

Optical98, the most important thing the photos you found show is that at some point the entire ceiling of the entry driveway fell down, falling onto a vehicle parked there. This had to happen after residents were able to safely exit out of the front door after the pool deck and part of the valet parking collapsed (the Nirs and the South American celebrity couple). It is unknown whether this occurred at the time of the building collapse or happened after. The ladder is clearly providing 2nd floor access to the building for emergency workers.

If the entryway ceiling collapse happened some time later after the building collapse that may have been an indication that the remaining building was unstable, but that is simply a guess on my part.

The surviving stairwell next to the elevators did not have an exit into the lobby. On the lobby level it only had an exit outside to the pool deck. Images show that there was no way to exit there as the decking collapsed a few feet outside that door (see image below). The other exit door was at the basement level and accounts said there was debris there that one group of residents climbed over to exit from the garage (I am guessing through the gaping hole we have seen at the back of the valet parking). I think I remember reading that group went down to the beach. They could have done so by making their way up onto the remaining pool deck and walking over debris to the exit gate by the pool. I found that surprising but if leaving through the garage it seems there would be no other way. This was the family I believe in an 06 unit, parents and two teenagers, who also rescued an 88 year old making her way down the staircase as they went down. Others said they could not navigate the debris at the bottom of the stairwell in the basement level and went back up to the second or third floor to a balcony out front to be rescued. This I believe was the woman who left a phone message accidentally that was played on the news as she went to other apartments on the floor to find neighbors.

https://www.youtube.com/watch?v=VM416Xg-oBQ

Precision guess work based on information provided by those of questionable knowledge

It does seem to be higher than the other slab areas which I assume are submerged. Is it possible that this is an upper slab that punched through? The slab elevation change, planters and the supporting beam I feel that might have failed first is to the south of this location.

Colostruct - yes, that makes the most sense to me that it's the pool deck slab. they may have just removed the pavers. someone in the tiktok video said "i thought it was an accident". if that slab pulled away from the building as one piece and dropped suddenly to the ground it would have made a huge bang.

CE3527 and Tropmet, thank you for responding! Yes, I knew the Stairwell exited to the pool deck vs the Lobby. What I was trying to determine was if the drive thru had fallen down as there hasn't been much photo evidence but survivors speaking of it falling. Also this verifies what you spoke of Tropmet, regarding the Entryway Ceiling >

Link

CE3527 it also seems less than ideal to be forced to bypass the lobby and direct street level egress and continue down to the underground parking lot in the event of emergencies. How can it be allowed to block the most direct egress route to street level and the supposed safest and fastest means to exit the building during emergencies.

Does anyone know at which elevation the piles were driven down at? I cannot find it in any of the drawing files I have. I just noticed the 3'6" depth of them.

Precision guess work based on information provided by those of questionable knowledge

Quote (rodface )

Those figures surprise me. Does that mean that a flat roof equipped with a parapet and scuppers as described would collect and hold a considerable amount of water before it was able to drain through those devices? I am somewhat ignorant on the subject, but I have to assume that the roof would be designed to shift the water to some other means of collection/discharge and would not be designed with the expectation that it would regularly hold up to several inches of accumulated rainfall?

This building used Internal Discharge as primary with only smaller elevated zones using scuppers as primary to discharge to the internal zone below. Overflow Scuppers are for when the rate of rainfall exceeds the flow capacity of the internal system or if a drain becomes blocked.

Quote (1503-44)

CE3527 it also seems less than ideal to be forced to bypass the lobby and direct street level egress and continue down to the underground parking lot in the event of emergencies. How can it be allowed to block the most direct egress route to street level and the supposed safest and fastest means to exit the building during emergencies.

Because this is Florida
https://i.imgur.com/ce6du4p.jpg

Approved by Palm Beach County Fire Marshall.
Edit: Hell, OSHA even turned a blind eye to this.

A 4 story apartment building now stands where a lake was 2 months ago. They just simply relocated and reshaped the lake. Logic and safety isn't a thing here.

CE3527

I don't think it's the pool exterior slab. I believe it is an interior slab. If I have the orientation right from the plans, there is a row of columns between the base of the ramp and the exterior of the building and we can see remnants of two of those column in the photo you referenced. I believe the outside of the building and the edge of the planter/pool deck would be further down the photo. (South on the drawings). Unfortunately, I haven't see a great photo of what the beam looked like at that location.

But, I do believe this to be "ground zero" for the collapse of the building (after initial collapse of the pool deck and upper parking areas). My gut feeling is that the column to the right of this "slab" you are pointing out is the one that finally collapsed and brought the building down. That makes sense because the building didn't lean much as it went down.

Edit. Whoops. I meant the column to the left massively failed and initiated the main collapse. This was AFTER the beam at the slab change initially failed and caused the first wave of damage.

The generator room would be located there if I am not mistaken.

Precision guess work based on information provided by those of questionable knowledge

OMG!

When I worked at Petrofac in Sharja, UAE we evacuated our 12 story building for an earthquake. Being the first to get the Heck out of there, I ran down the stairs to ground level and found massive doors. They were easy to open at the time, because I was one of only two people to reach the exit that quickly. If there had been any more people there at the bottom of the stairs, we might have been crushed up against them by a crowd, because the doors opened only toward us.

As soon as the all clear had been given and I arrived back at my desk, I found the company's safety violation notice form used by our construction activities group and wrote them up. It took awhile and I had actually left that company by the time, but a year later I was told that they did act on the violation I wrote up and reversed the direction of the doors to open outward, exactly as I had told them. Surprisingly, or not, the practice of outward opening emergency doors is far from universal and they are in fact common in many countries, in the EU and UK included. Inward opening emergency use doors are extremely dangerous.

Quote (CE3527)

Does anybody have any theories on this concrete slab in the post-debris removal photo?

Should be the basement slab which is not entirely on grade. There are pits for the storm drainage system below. One of the larger ones is between that slab and the end of the ramp.

To add:

The water level will change with the tide. The TOS elevation was surveyed at -0.27ft NAVD so it’s underwater outside of low tide.

Quote (AutisticBez)

You need someone with autism super powers to imagine ways that buildings can collapse.

I disagree with this statement. We (structural engineers) deal with this every day, if we deal with non-routine arrangements, different restrictions, etc. We all imagine the ways that a building would collapse under different combinations of load, damage, etc.

The Generator room location >
Link

Probably not a serious comment there NOLA.
I know this is serious business, but can we see the humor and let it go.... just this once.

Pretty good views of the Collins St side from 6/24 here:

https://youtu.be/GyrvMi-4QE4

Quote (CE3527 (Civil/Environmental)14 Jul 21 21:35)

maybe it's the pool deck from above

Nukeman948 (Electrical)'s photo was taken very recently, from the area of the pool, looking west and south East and South West and North _{(pool is on the ocean side of the building) (sorry, I get confused due to the ocean being in the other direction on my coast.)} toward the debris pile left by the demolition. The entire pool deck has been removed. They threw off the pavers, sprayed the sand off with a fire hose, cut holes in the deck with the world's hugest SkilSaw, and let the excavators have a go at it. The fort you're looking at was on the garage floor under the apartments, I believe.

Quote (because the doors opened only toward us.)

in most jurisdictions, the doors being a means of egress would have to open outwards.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

Well one thing is for certain, those that cleared out the Ramp area...they now know what was found there. Whether it's considered the trigger or a consequence of other events, they are aware the Public wants to know what was found there.

They (not the crew but those whom have authority of these items) need to make a statement, soon.

Quote (SFCharlie (Computer))

The fort you're looking at was on the garage floor under the apartments, I believe.

That part confuses me in the recent drone flyover. Why would they place a C-shaped fort at garage level in the driveway bounded by parking spots 16, 17, 24, and 25? I imagine everyone here noticed it; I had guessed for some reason they moved the remnants of east staircase away from the ramp.

• https://files.engineering.com/getfile.aspx?folder=3b2cd6ec-0cde-4ef4-93df-4

Is there any rational as to why the 2, 3, and 4 PIFs would only be ~53.5" below the surface for this type of geographical location? This seems very odd to me. On a property on this shore line we typically drive H piles down to at least 15ft because of the underground water flow.

Precision guess work based on information provided by those of questionable knowledge

Still some weird political BS going on: Link

Auri, those are three beams that were above the garage level columns that were just to the east of the garage entrance, see photo below. I can only assume that when that last part of the building came down, the columns were reduced to rubble and only the beams were left, but we have no way of knowing if that is the case or if they removed everything under the beams and left them there. The position is close to the location they were when raised on the columns, perhaps a bit south of it? based on the rebar which must be remaining from the columns. That section twisted when it fell. This photo below is from that garage walkthrough part of the video showing unit 611 from last year.

Auri - I think what we're looking at is three beams that were supporting the garage/ceiling first floor slab. They fell straight down in the collapse but remained in tact.

Quote (Demented)

Is there any rational as to why the 2, 3, and 4 PIFs would only be ~53.5" below the surface for this type of geographical location? This seems very odd to me. On a property on this shore line we typically drive H piles down to at least 15ft because of the underground water flow.

The piling elevations are not in the plans. They’d be attached to the DERM certs. It’s still unknown if it’s all precast driven or the mixture with driven at the boundary and franki for the interior.

Quote (Roga50)

Still some weird political BS going on: Link

That's deeply troubling, Maybe surfside PD has their three best men on the case, working in shifts.

Quote (Roga50)

Still some weird political BS going on

Allyn was retained by the Town of Surfside which presents a conflict of interest. His expertise nor character are in question, just who hired him.

This area has me baffled both in the why in the first place and how was this revised and actually built.

Quote (Optical98)

Well one thing is for certain, those that cleared out the Ramp area...they now know what was found there. Whether it's considered the trigger or a consequence of other events, they are aware the Public wants to know what was found there.

They (not the crew but those whom have authority of these items) need to make a statement, soon.

They may or may not know what the triggering event was but while they certainly may know the public wants to know their findings they will be in no hurry to tell them. It's the same with every major event like this, the details will be released when they are ready to release them. It took well over a year for anything of interest to be released regarding the bridge collapse at FIU.

Quote (ce3527)

Does anybody have any theories on this concrete slab in the post-debris removal photo? It appears to be fairly in tact in areas where it's exposed.

Is it possible that this is the first collapse that Sara Nir in 111 heard at 1:10 am?

For 25 minutes, Sara Nir heard knocking "construction sounds" that increased in intensity over time. Then she heard a "smash" that sounded like a wall collapsing. That is what caused her to go out to speak to the security guard in the lobby.

****Edit: I just read for the first time that Chani Nir says she was hearing the knocking sounds when she got home at 11 PM. So the knocking sounds may have been going on for over two hours.****

Here's a basic timeline that shows this and other events, along with a few building-related quotations from early 911 calls. It may provide some use in testing various hypotheses.

Can anyone explain how this 12th Floor PH parapet is on the bottom of the patio deck pile, where deck did not fail, when the PH was the last floor to find the ground? See Tropmet's picture above for larger image at bottom.

Quote (Allyn was retained by the Town of Surfside which presents a conflict of interest. His expertise nor character are in question, just who hired him.)

I've done lots of reports for insurance guys... and it doesn't matter who hires me... report is essentially the same.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

Quote (Thermopile)

Can anyone explain how this 12th Floor PH parapet is on the bottom of the patio deck pile, where deck did not fail, when the PH was the last floor to find the ground? See Tropmet's picture above for larger image at bottom

That’s a planter.

Quote (dik)

I've done lots of reports for insurance guys... and it doesn't matter who hires me... report is essentially the same.

What does experience with reports for insurance co’s have to do with a building department that was already flagged and under investigation? Surfside is at the very bottom of the list with regards to jurisdiction.

I was personally involved in the Market St collapse in Philadelphia and as a result, would question anything done on behalf of the municipality that had responsibility, regardless of who prepared it.

Quote (Santos81 (Specifier/Regulator)15 Jul 21 02:11)

baffled both in the why in the first place and how

...not sure I know which kind of why you're looking for? Here is the landscape vision:
(also so, the YouTube channel BecauseSurfside has a video from about a month ago about "undergrounding" _{Sorry, red herring, that was about the cost of undergrounding utilities} Looks like they wanted to use every inch of their property underground and still have landscaping.)


SF Charlie
Eng-Tips.com Forum Policies

Quote (would question anything done on behalf of the municipality that had responsibility)

It depends entirely on the integrity and the skills of the engineer. His skills appear to be maybe more than adequate.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

Quote (Tropmet (Marine/Ocean))

Auri, those are three beams that were above the garage level columns that were just to the east of the garage entrance

Thanks a bunch for that. Those are precisely in the drop down location. I had not thought to look for the beam schedule as they appeared much too tall; the recovery crew instead cleaned all around them but had no need to remove them with nothing trapped underneath.

Quote (Thermopile (Aerospace))

Can anyone explain how this 12th Floor PH parapet is on the bottom of the patio deck pile, where deck did not fail

The first mid section of building basically fell within footprint, and it's an unimpeded fall for the 12th balcony and roof in the stairway exit area:

Quote (SFCharlie)

not sure I know which kind of why you're looking for

It doesn’t really work as drawn with the ramp down in place. Nothing really holding the load from the generator room.

Quote (dik)

It depends entirely on the integrity and the skills of the engineer. His skills appear to be maybe more than adequate.

Allyn is a great choice and it’s not a question of his skill or integrity. I cannot say the same for whom he is preparing his report for and what they may choose to include or redact.

Quote (Santos81)

I cannot say the same for whom he is preparing his report for and what they may choose to include or redact.

What are you suggesting their liability or motive is in this?

@Spartan, You forgot to add the smiley... it might be a little suspicioius that they dropped the adjacent building on a 'crime scene'... but refused to allow qualified technical people take a look at it.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

Quote (Spartan5)

What are you suggesting their liability or motive is in this?

There’s been too much focus on the 40yr Re-Certification of a building that was designed for a 30yr life.

Miami-Dade County requires an ANNUAL Minimum Housing Standard Inspection of which incorporated municipalities perform on their behalf. These are included in the FOIA documents. On top of that, there were Building Officials on the premises for various inspections every 3 DAYS on average. Their focus unfortunately seemed to be limited to Sea Turtle Lighting Compliance and nuisance WWOP complaints which served to highlight the complete and total clusterfuck that department is.

Quote (dik)

it might be a little suspicioius that they dropped the adjacent building on a 'crime scene'... but refused to allow qualified technical people take a look at it.

So those from NIST, Army Corps of Engineers, and engineers retained by FEMA, Miami-Dade County and the State of Florida don’t count? Allyn’s suggestion that KCE had not had any access to the site and the staging area where evidence is taken for reconstruction is completely misleading as well.

The full 45 minute recording of 911 calls was released - https://www.youtube.com/watch?v=gXGIWSkfW1s

It's interesting how the first person who calls in calls it an explosion at 1:16. Saying it sounded like an accident made a lot of sense, especially since part of that slab looks like it fell on a car.. but explosion seems like an odd descriptive word for slab that's fallen.

Tropmet, Yea.. about that pic too, there was definitely a maroon car parked in that spot 39 next to the column too, I watched them pull it out of the rubble yesterday.

I've been reading these threads with great interest for weeks, some great and interesting discussion and analysis.

I think the most revealing evidence is the ring video as it's the only progressing evidence. I've been doing some assessment of this to post shortly (did try to post it before but the long post didn't post and needed to build up to posting it again!!). However I have one immediate simple question.

I'm not a structural guy so apologies for any naivety. But in the ring video, the pillar or wall beside the door goes from straight to perpendicular prior to full collapse, with no obvious sign of broken slab (punch through or similar).

To this layman's brain, this means that the vertical gap between floor and roof slab must have reduced at this point unless I am missing something?

There's only two ways this could occur if this is the case - either the floor slab INCREASED in height (can't think of a single failure scenario that would cause this), or the roof slab dropped?

If the roof slab dropped, does this actually add credence to the roof failure scenario? I should stress that this has never been my personal thought on likely failure, so not trying to prove this, but this is troubling to me in terms of something not going on higher up the building?

I'm sure I'm misunderstanding something...

Quote (jbourne8 (Computer))

there was definitely a maroon car parked in that spot 39 next to the column too

Maroon? There is some pretty strong maroonish trace under what has been referred to as the fallen slab.

zebraso, the maroon car I was referencing is further back in the garage.. in spot 39. It was very flat when they pulled it out, it was late yesterday. It's a comment about this pic though, from further up in this thread.

Quote (Santos81)

It doesn’t really work as drawn with the ramp down in place. Nothing really holding the load from the generator room.

Isn't it showing a beam running along the L & M lines either side of the generator slab? Somewhere in the various documents, they mentioned it being a 250kW generator. Taking a Cat D250GC as an example, that's a dry weight of 5324.2 lb to 6735.1 lb. It's not lightweight, but it's also not going to require a crazy amount of structure.

Why there? My guess is that it was simply a bit of space with limited potential for use, but big enough for a generator and crucially had sufficient exterior wall for cooling air grilles. A standard diesel generator produces about the same waste heat as electricity, so it has up to 250kW of heat to dump via airflow through those grilles.

Quote (jbourne8 (Computer))

further back in the garage.. in spot 39

Yeah it's a long shot again. I just read "maroon" and I knew I saw that maroon in my image and thought it did not belong there back when I first looked at it in the sense it was out of place. I know people will say it's a spurious artifact, but there are not too many all colors or the rainbow stuff like chroma interference moire so it occurs to me that there is something to it. It's just hard to say it out loud (again). I have to note that there is not much depth reference in the image. A lot of what the depth of anything appears to be is based of a loose collection of reference points. I just try to keep and open mind.

Quote (Murph 9000)

Isn't it showing a beam running along the L & M lines either side of the generator slab?

Slab Drops with ties from non existent slab into nothing but air between L/1 and M/1.

Quote (NOLAscience)

I like your theory. That's been rattling around in my head for the past couple of days, too, but I didn't put it into words like that.
What is your explanation for the 5 to 10 minutes between the failure into the garage and the building collapse. Why does the load redistribution take that long?

Deformation Theory of Plasticity in Steel.
Concrete works in compression. Steel works in tension. Concrete needs steel. Steel rebar is used for tensile strength.
Steel gets stronger before it fails in tension, yes it's bizarre.

This is why wood high rises in earthquake zones (currently CLT lumber but my bet is we figure out how to just use studs with shear walls with an occasional transfer one day) are a new goal.
Wood performs superior in unusual events, making it an amazing building material.
Wood works in both tension and compression, along with not just failing out of nowhere like concrete (steel slowly fails too)...
Concrete moment frame construction in CA is now severely limited (practically banned) after the 1971 San Fernando and 1993 Northridge earthquakes.
There's no plan B to failure in a two-way moment frame concrete slab construction, it's not safe over time.

Quote (jbourne8 (Computer))

in spot 39

One more time. I'm a little slow sometimes. There may be a faint trace of maroon in the area that would be spot 39. I don't know what else that color is. It's in the purple range. Not as strong as the purple color is shown up front where there is more light. I'm not saying this information is worth anything. But it might show that camera can detect colors in dim light (or not).

zebraso, all I saw there was a black spot.. that's actually what drew my attention to it, was how dark that spot was. I think the back wall of the garage looking green in most videos is kind of proof of how crummy that camera is really. The entire back of the car looked completely in tact too.. so I doubt it was missing a back bumper or something, if that's the suggestion.

Quote (warrenslo)

I'm still lurking but nobody has changed my mind. The roof anchor work caused the penthouse roof to collapse onto the pool deck.

Your theory is far more probable than some here want to admit. Nobody has accounted for the report that Elena Blasser, living in Penthouse 11 (12th story, x11 stack), was awoken by loud creaking noises at approximately 3 or 4 AM the day before the collapse. Her son said that she was so disturbed by this loud creaking noise (as in, it was not a normal occurrence for a person that had lived in the building for years) that she was unable to go back to sleep. Considering nobody else in the building reported hearing "creaking noises" would suggest that she was the closest in proximity to the source of the noise. She was directly below the section of the building that appears to be missing a parapet in the security camera collapse video. In the days leading up to the loud creaking noises, contractors were attaching davits to the roof slab and load testing them. The Association Reserve report from 2020 noted cracking at the parapets and the engineer instructed contractors to inspect and repair any damage to the roof slab. Sara Nir stated that she first heard noises at 12:45 AM and that those noises seemed to be coming from ABOVE her. She said those noises continued for at least 25 minutes and became increasingly loud. At 1:10 AM she said she heard a sound that she described as a "wall collapsed" in the condo ABOVE her. She then went to the lobby and that is when the garage collapsed (1:15 AM). She observed activity that she thought was coming from above her for a half hour before she states she saw the garage collapse.


The argument challenging the roof theory is that nobody called 911 from the top floors -- there were many calls made to 911 that the media did not mention in any of their reports. In one call placed to 911 from the building, the operator answered the call and the call was disconnected, as though the caller was caught a collapse at while making the call (1:17:06 AM). Others could have been sleeping when the structure above started to fail (if that's indeed where it started).

There is a reason Allyn Kilsheimer was taking core samples from the penthouse. He knows better than to simply dismiss the noises Elena Blasser heard the day before the collapse, the video showing a missing parapet, and the fact that contractors were actively working on the roof in the days leading up to the collapse.

Entertaining the idea that the series of events began at the roof doesn't mean that the building collapse wasn't caused by column failures at the garage level. A failure at the roof could have triggered the events at the pool deck. There's no justification for ignoring evidence pointing to the roof.

Quote (Santos81)

The overflow scuppers were not the primary RW drainage outlets for the roof or UPH parapet balcony. Their base elevation was 7” above TOS and incorporate spring loaded doors.

I don't see spring loaded doors. It appears that the scuppers were no more than 5" above the top of the gravel/flood coat.

Quote (hochhaul)

The problems with the roof theory include:

1. The main roof and at least most of the parapet seems intact as the top of the building rotates and slumps in the CCTV footage. Floor-matching with the late-falling section shows no missing floors.
2. Identification of roof items at the bottom of the debris pile or in the garage is unconvincing.
3. Lack of 911 calls for the upper floors, maybe.

Probably other items indicating that design, construction and maintenance problems with the pool/patio deck are enough on their own.

Occam's razor only fits the roof theory if you discount the floor-matching by numerous analysts of the CCTV footage, and other recognisable features in the video. If you accept that a floor has descended in the first-falling section prior to the CCTV, Occam's razor needs no involvement from the roof. It remains possible that some small damaged section of parapet is initiator - the pool deck was obviously a weak link and ready to let go anyway - and I don't think anyone here has discounted that possibility.
Allyn Kilsheimer is not directing operations, at least according to his interview, so who is coring what and why is an open question.

Quote (jbourne8 (Computer))

I doubt it was missing a back bumper or something, if that's the suggestion.

No. I'm trying to cut down on being obtuse. I really missed the context of how far back this was in reference to. And I agree with where the columns are said to be although it's almost impossible to actually see them. Although looks like something is actually leaning against M12.1 (like a broom that probably is not a broom). I tell myself the columns are there because they have to be. The purple color along the fallen deck in front is a mystery as far as I am concerned. I could just say "artifact". That's the easiest way I guess. Whatever the case, it does not seem to have any significance at this point. The teal colored thing would seem to be well in front the column between 39 and 40 because I don't see anything that near the back wall being that well lit or is it just that the area is not obstructed by debris? I'm assuming there is a dust cloud in there and that is why some areas look opaque. Otherwise the lights should illuminate all the way back?

Quote (hochhaul)

The argument challenging the roof theory is that nobody called 911 from the top floors

In my opinion the burden of proof lies the other way. There is no solid evidence supporting the roof theory (and plenty against it as pointed out by AusG); and unless some is supplied, the theory cannot be taken seriously.

Given you joined the forum two days ago, I suspect a sock puppet account.

OK a few more thoughts around the Ring video. I am not at all knowledgeable around structural engineering so cant fully decipher these, but there are a few things that seem very clear to me from intense assessment of this video.

1) I am not at all convinced that the first image in the video is a "bug". This looks more to me like a temporary loss of video feed. The audio continues during this "freeze frame". Ring uses SIP internet protocol to transmit its audio and video, and video is (of course) larger bandwidth in nature. whilst I can't determine it for definite, I would be reasonably convinced that the Ring camera transmits its audio and video feeds separately, and something led to the loss of video during these few seconds - could be coincidental, or could be relating to the failure. There certainly appears to be a "flash" of light at the top left of the image immediately after freeze, which could be something electrical, causing interference in transmission (its a reasonably safe assumption that this camera is wireless not wired, and wireless is highly susceptible to local EM events). My view therefore is that we are not seeing the tail end of something that we dont see the start of - but rather that the first image is chronologically accurate and an event in those first two seconds led to the slanted image we see later.

As an aside on this part - sample size of one admittedly, but I also have a Ring camera and try as I might I cannot replicate this "freeze frame" element in normal usage.

2) At the end of the video, it absolutely appears that the table that the camera is on starts sliding to the right hand side. I am actually not sure this is the case - or at least its not a "free slide" of the table purely due to gravity. Throughout the video, you see a "pillar" of white at the left extreme. I am pretty sure that this is either the inside of the balcony door frame, or it is a jutting out bit of wall (these were in the condos in the corners of this room if you look at some of the sales pictures for these condos). Note that during this "slide" of the table, this part of either wall or door frame never changes its reference point to the camera.

This implies strongly to me that rather than "sliding", this table was being "pushed" by this wall. If this is the case, the other conclusion is that this wall was moving in relative isolation. It would appear this was moving in isolation from other walls (albeit this is clearly hard to work out) but categorically it was moving in isolation to the floor of the condo - there are plenty of reference items that confirm this.

Note that we do not really know that this camera was in fact on a table, its merely on a platform of some kind. Could this be a wall mounted shelf?

3) If the above implications are correct (admittedly could be off) then this has a very interesting further conclusion - that immediately prior to the point of collapse, the outside shell of the condo (i.e. the external door frame and presumably balcony) was moving relative to the rest of the condo. This period is long enough to know that this was not DURING collapse, but just pre collapse. What does this mean? I have no idea, but it doesnt really align to the failure of a column underneath the "body" of the condo I dont think.

4) A quick note on the timings in the video also. I know there have been a couple of comments that at least part of this video could have been during freefall. I categorically dont believe this is the case, for a couple of reasons. First of all any significant downward motion in the condo could not have occurred without inertia moving at least some of the contents/jolting them - all of them. The only item we really see move in this way other than wall forces impacting on them is the empty TV box which judders rather than "lifts". Secondly, we need to consider WHY the camera stopped recording. This could only happen for three reasons (two of which are largely the same). Firstly, the camera lost power. Secondly, the camera lost connectivity. Both of these therefore we can consider to be loss of utilities/services. Thirdly, the camera was destroyed. I don't believe that it can be the third reason - no matter the speed of collapse and destruction, I don't believe that we wouldnt see a single frame of destruction occurring prior to the camera going completely offline. The failure was sudden and immediate. As such, I am pretty sure that this camera stopped recording due to a loss of power or connection - which was almost certainly triggered by the commencement of vertical movement of the condo. There are other reasons as well - right up until the end of the video, the debris from above continues to fall - if the condo was in (or starting to) free fall, you would see a relative slow down of these particle falls - you do not.

5) A note on the "slanting" of the condo, be this in the horizontal plane of the video or the depth plane. On further assessment, I don't believe that theres clear evidence of this (although to be clear not saying this wasn't occurring). A lot has been made of the change in fall of the particles, which initially had me confused as well. However when you look at individual particles very carefully, there is a clear tendency towards the vertical plane, rather than a straight line fall. This is the case on both sides of the camera, and also when particles are dead centre, you dont see this gravity influence effect as if there was a horizontal slant.

I am less sure on a vertical slant. I think you would see more evidence of this in the video - other items moving etc. The particles themselves show no change in luminosity in flight compared to the vertical falls, which you would see if the backwards vertical slant was bringing these particles closer to the camera whilst in flight.

6) I think more likely, given 5, that the SOURCE of the particles was moving in ceiling above the camera. The unusual trajectory I cant fully explain, but this could be due to ejection under stress (for example, concrete failing on a side of a rebar rather than directly below it?).

Equally in line with this, I do think pretty categorically that the particles are concrete not dry wall. We are seeing these being generated for (minimally) 10 seconds, in ROUGHLY the same location. I simply dont think drywall is robust enough to do this. Equally, the location of this camera directly below concrete beams to support the door frame etc would back this up, as well as the lack of any obvious visible cracks in the rest of the ceiling drywall.

7) The deformed pillar beside the door, for what its worth, I have calculated to have "relatively" moved the base of this pillar to the left by around two widths of the pillar.

What does this all mean? I really dont know, but I'm hoping someone else may.

Having read 6 threads on this and been thoroughly convinced of the obvious if "not sensational" pool deck collapse due to water load leading to pulling/other forces causing column collapse, my untrained eye (especially the movement of the camera at the end apparently caused by a wall) does start to lead me to question this is the full story. Did something fall off the roof with force and strike the balcony of 711 or the balcony above, leading to ultimate failure of the outer balcony and wall on this area? It would tie more closely with what is seen in the Ring video. Unsure if this could cause a "pivot" effect - i.e. balcony struck, causing a shift of the slab inside the condo up to balance this downward force and hence deforming the pillar. Of course even if this is the case, this is not necessarily full cause and effect, and this could merely be a symptom in some way of a lower collapse. But I think the duration is significant enough that this may not be the case.

Worth mentioning as well that in the last 1.5-2 seconds (after the box jolt) the camera does not just move right relative to contents of the room, but also DOWN. This is not as obvious, but when you look at it frame by frame theres a definite downward motion compared to contents.

The jolt of the box itself is a little odd in the way it happens, mainly as the box does not move in the obvious way. The rear bottom corner actually moves more into the centre of the room. This is despite the fact that its CoG is outside of its base, it presumably isnt resting on anything behind it (given that theres now more space behind it than there was at the start of the video), and the boxes it is resting on very slightly (but definitely) move towards the centre of the room as well. If the room itself was slanting, then this would further mean that the likely fall would be rear bottom corner towards the wall, therefore towards a flatter profile, but it does the opposite. This would either imply the room is not slanting, or (given the other reasons it should have fallen more rather than become more upright) something has happened to the floor or wall behind it that we cannot see that has pushed on this corner.

Whether all of this has any ring of truth or is just a layman talking rubbish, I really dont know. But it might provoke some thinking.

EDIT - looking back at earlier posts and floor plans etc - does this end movement imply column M10 was the one to cause the actual final collapse? I am still not sure that this was the case until the very end of this video though.

Also - having looked back I can see no confirmation that this camera is actually a Ring camera. This was reported somewhere (cant find where) but not apparently by the resident of 711, so I think its an assumption by a media outlet. However it doesnt change the fundamental analysis.

Quote (Santos81)

The piling elevations are not in the plans. They’d be attached to the DERM certs. It’s still unknown if it’s all precast driven or the mixture with driven at the boundary and franki for the interior.

I'm assuming based off of dimensional call-outs for 3'6" and 48" of piles, the 2'2" slab elevation for the parking/basement level, 4" pile to cap recess, and 32" pile cap height.

The simple fact that depths of the piles are called out makes no sense to me.
I could completely be reading the plans incorrectly, I don't doubt that one bit. They're a mess and they make the Fontainebleau renovation plans look like a masterpiece.

It was Miami in the 1980s. Augercast piles? Especially with depth callouts, that would be the easiest pile job ever. Drill to depth, insert some corrugated steel tubing to stop the water ingress, pour your concrete, and call it a day. (Old but very common practice here, and wasn't known back then but we know today, water flowing underground around steel pipes leads to open voids). Only deviation being dropping a wired up #7 cage assembly. Few inches of concrete at the bottom so the 72" long rebar cage (Or 78" long rebar cage for the 48" piles, but we're talking about 6" here and you can easily cheat only using 72" long embedded reinforcement, because just like using the incorrect size nelson studs, aint no body going to know once it's in the ground.)

I fully understand this is NOT how it should be. But I'll refer back to my story of the kid using his fall arrest harness to try and swing to a lower level during construction as the level of brilliance building our high rises.



Precision guess work based on information provided by those of questionable knowledge

My son plays Portal 2 a lot. Maybe someone was playing with a portal gun, and either managed to make the Penthouse destroy the parking deck, or moved a speeding car on the road outside, end up knocking over a column. I'd photoshop my new theory, but then I'd lose the ability to claim patent rights on the portal gun. Until I lodge that patent, I'm going to have to go silent on the matter. Definitely don't let anyone know about my invention.

Let's just say that if a car did knock the column down, it probably burnt up under the weight of all of that building falling onto it. Maybe you'll only find a drive shaft left?

I have not seen mention of a geotechnical report.

This was done for the
Miami Convention Center
Might be representative of soils in the Surfside area, might not.
https://www.miamibeachfl.gov/wp-content/uploads/20...

Sorry there is one other observation here as well which I think is important enough to call out itself.

The 711 video has its safe to say NO events contained within it that are more impactful (to this condo at least) than the event which initially triggered the camera, and the event at the end of the camera.

In addition, if we assume (and I think given both the video and audio that this is a certainty) that the end of the 711 video is the final collapse, then clearly the triggering event CANNOT be the same as what occurred to cause the garage area debris, as the timelines do not match up. Absolutely minimally (and in truth longer, but we can say this as fact), the garage debris was created at least 17 seconds prior to the overall collapse due to the length of the TikTok video. In truth this is longer (probably many minutes). The 711 video is only 12 seconds long.

Therefore, what is the event that wakes up the camera 12 seconds before complete collapse? Note that this event appears to be more impactful to 711 than the pool deck collapse, purely by the fact that it didnt wake the camera up (as far as we know). And is it significant (or not) that within this 12 seconds there are other "events" (primarily 7 seconds in) that did NOT cause as much impact? Probably not - but on the assumption mentioned somewhere above that the noises heard are progressive column failures, would these not be minimally as impactful upon the condo in these first 7 seconds as the initial event? Again - probably not, but thinking aloud. The important element rather than this line of speculation is that 12 seconds prior to collapse (and again at 5 seconds prior, albeit not as apparently immediately significant) there was clearly a significant event which affected the building, which was not the pool deck collapse (if we assume that the TikTok video demonstrates the aftermath of the pool deck collapse, which of course I think isnt in doubt).

Quote (clouditguy (Computer))

1) I am not at all convinced that the first image in the video is a "bug". This looks more to me like a temporary loss of video feed. The audio continues during this "freeze frame". Ring uses SIP internet protocol to transmit its audio and video, and video is (of course) larger bandwidth in nature. whilst I can't determine it for definite, I would be reasonably convinced that the Ring camera transmits its audio and video feeds separately, and something led to the loss of video during these few seconds - could be coincidental, or could be relating to the failure. There certainly appears to be a "flash" of light at the top left of the image immediately after freeze, which could be something electrical, causing interference in transmission (its a reasonably safe assumption that this camera is wireless not wired, and wireless is highly susceptible to local EM events). My view therefore is that we are not seeing the tail end of something that we dont see the start of - but rather that the first image is chronologically accurate and an event in those first two seconds led to the slanted image we see later.

As an aside on this part - sample size of one admittedly, but I also have a Ring camera and try as I might I cannot replicate this "freeze frame" element in normal usage.

Ring cameras do have a snapshot mode, which can only be set up and viewed through the mobile app. The frequency of snapshots is user-configurable. It's not clear that these snapshots get appended to motion-activated video, as some have assumed to explain the initial video frame. BTW, it's recommended to mount this sort of Ring motion sensor to the wall at a height of 7' or 7.5'.

I don't think "something electrical" can explain it either, though, because I'm having trouble imagining an electrical event that would have left the internet connection to the camera intact.

Quote (clouditguy)

Also - having looked back I can see no confirmation that this camera is actually a Ring camera. This was reported somewhere (cant find where) but not apparently by the resident of 711, so I think its an assumption by a media outlet. However it doesnt change the fundamental analysis.

Good catch! I don't think Ring was mentioned anywhere in the media; possibly it came directly from the eponymous Reddit post.

I found a longer more complete 911 call log, listening through it now to see if there's anything useful but I sadly doubt it (everyday non-engineers + panic and fear) but probably worth checking anyway.

https://www.youtube.com/watch?v=v2zRuxNjG2I

Quote (Demented (Industrial) 15 Jul 21 10:54 Quote (Santos81) The piling elevations are not in the plans. They’d be attached to the DERM certs. It’s still unknown if it’s all precast driven or the mixture with driven at the boundary and franki for the interior. I'm assuming based off of dimensional call-outs for 3'6" and 48" of piles, the 2'2" slab elevation for the parking/basement level, 4" pile to cap recess, and 32" pile cap height. The simple fact that depths of the piles are called out makes no sense to me. I could completely be reading the plans incorrectly, I don't doubt that one bit. They're a mess and they make the Fontainebleau renovation plans look like a masterpiece. It was Miami in the 1980s. Augercast piles? Especially with depth callouts, that would be the easiest pile job ever. Drill to depth, insert some corrugated steel tubing to stop the water ingress, pour your concrete, and call it a day. (Old but very common practice here, and wasn't known back then but we know today, water flowing underground around steel pipes leads to open voids). Only deviation being dropping a wired up #7 cage assembly. Few inches of concrete at the bottom so the 72" long rebar cage (Or 78" long rebar cage for the 48" piles, but we're talking about 6" here and you can easily cheat only using 72" long embedded reinforcement, because just like using the incorrect size nelson studs, aint no body going to know once it's in the ground.) I fully understand this is NOT how it should be. But I'll refer back to my story of the kid using his fall arrest harness to try and swing to a lower level during construction as the level of brilliance building our high rises.)

The original plans are, as you noted, terrible. Full of discrepancies and missing and inconsistent information. To clarify, I think the depth you are seeing refers to pile cap thickness, not depth of pile. The depth or length of piles (either 150 ton PIF or the original 50 ton PC) should have been determined by installing a test pile where in the case of the PC would have been driven to practical refusal. How they determined the 150 ton depth of the PIF (aka franki pile) back in 1980 I don't know. Also note that the original pile cap plan which shows closely spaced square concrete piles (PC) was not apparently revised to show a new layout with the PIF. As you can see below, they only provided revised section views for caps with 2,3,4 PIF and the two H shaped shear wall caps. There is no revised cap plan that shows the foundation for the columns that failed (K,L,M). The foundations supporting the main columns that failed cannot be determined from these plans. To my mind, there have always been 2 separate questions regarding the collapse which are; 1. what triggered the collapse? and 2. why was the damage not more localized? The second question comes down to the original design being flawed, and there is certainly evidence in the original design documents and photos of the collapse debris to strongly suggest that the building lacked the type of redundancy that would have ordinarily limited the damage.

The more I look at it I dont think it is a Ring camera - there would be usually some time/logo stamp from a Ring, which I cant imagine the resident would have taken the time to remove. As I say, probably not that material.

Re: my thinking on loss of video, just to expand. Wireless (which I definitely think its a safe assumption this camera is) is simply an EM wave. An Electrical short of some form would equally cause an EM wave, which (can) cause interference.

Interference in this way would not be an "on/off" thing, it would simply degrade the signal and therefore mean that the packets sent are more likely to be corrupted and so enter what is called a "backoff" due to corruption or collisions. Audio and Video streams are almost always sent seperately, and typically the video stream is roughly 10-20 times the size of the audio, and as such much more likely to be corrupted (as there is more data which can be corrupted). In most such streaming protocols, if the packet is corrupted, the recipient simply rejects it - in many cases it will request a retransmit, but this depends on the protocol - it may simply drop it and "move on".

Admittedly, it is a little unlikely that the device has dropped every video packet, and accepted every audio packet, which is largely what appears to happen from an "end user" perspective. However it all depends on the proprietary implementation by the vendor of the camera - they may be more aggressive with not trying to recompose a heavily artifacted image.

To be clear - I'm not 110% behind this. But I dont fully buy into the initial image being a simple "bug" either, especially given it (equally) is at night and would at least appear to be chronologically "close".

@clouditguy

I think the camera likely was battery powered (or could be), but it's router, and the router's cabling to whatever it's peered to, and potentially whatever router and cables are peered to that if it's in the same building were likely destroyed rather quickly - especially it's cable/fiber uplink.

I think that first frame was likely one of it's previous frame's it had captured (last one in the video buffer), and that was likely what was being diff'ed to detect motion. There may have been a delay between when it detected motion and started recording, no idea how long that could be.

Quote (clouditguy (Computer))

The 711 video has its safe to say NO events contained within it that are more impactful (to this condo at least) than the event which initially triggered the camera, and the event at the end of the camera.

Let's not forget, the camera is a low power device likely to introduce around a second of latency by the time a video frame is encoded and actually sent out within a packet. And while it's eerie and perhaps exhilarating to analyze all the details from... found footage, unless there's "smoking gun" evidence regarding what happened to the building 10 or 30 minutes before recording, it doesn't really matter whether L 10 or M 10 was sinking a few seconds ahead of the other when it's all several minutes past the garage "explosion" which obviously altered the sequence of progressive failure and of which we wish we knew the cause.

Quote (tnwaits1)

The original plans are, as you noted, terrible. Full of discrepancies and missing and inconsistent information. To clarify, I think the depth you are seeing refers to pile cap thickness, not depth of pile. The depth or length of piles (either 150 ton PIF or the original 50 ton PC) should have been determined by installing a test pile where in the case of the PC would have been driven to practical refusal. How they determined the 150 ton depth of the PIF (aka franki pile) back in 1980 I don't know. Also note that the original pile cap plan which shows closely spaced square concrete piles (PC) was not apparently revised to show a new layout with the PIF. As you can see below, they only provided revised section views for caps with 2,3,4 PIF and the two H shaped shear wall caps. There is no revised cap plan that shows the foundation for the columns that failed (K,L,M). The foundations supporting the main columns that failed cannot be determined from these plans. To my mind, there have always been 2 separate questions regarding the collapse which are; 1. what triggered the collapse? and 2. why was the damage not more localized? The second question comes down to the original design being flawed, and there is certainly evidence in the original design documents and photos of the collapse debris to strongly suggest that the building lacked the type of redundancy that would have ordinarily limited the damage.

However, we have drawn to scale.

Measure that pile cap to scale off the known 4".

Fuckin oops

Edit: Were the caps supposed to be the 3'6" sections? Because that is not how the plans call it out. As read, and hopefully not as built, that building stood on 6ft legs.

Thanks both.

To be honest the more I look at this in terms of my first point in my post above, I dont think this really matters all that much in truth. To be clear not just saying this because there are counter views :) it just probably doesnt change much in truth.

For what its worth I would quite strongly disagree that an internal security camera is likely to be battery powered. This isnt a Ring doorbell (for example).

I do think its of material note to look to understand what happened in the seconds leading up to the actual collapse, as this can give an indication as to the method of collapse. Not to me admittedly without structural knowledge, but others may.

I do think the key points of note above though are:
1) the outer edge of that condo is quite clearly moving DOWN and RIGHT immediately prior to collapse - this is to be clear not only in relation to the building, but in relation to the rest of the condo, which at that time was not showing signs of huge ongoing movement. I do think this is quite interesting information to cross match against the working theories on failure - especially is it would (to me at least) strongly imply a column failure causing final collapse at the edge of the building rather than further within. It could also imply (albeit I'm stretching my already very limited concrete knowledge here) that already prior to collapse the outer wall of the condo had separated from the condo floor slab. In fact from the layman, it doesn't just imply this I must say but really shows it, as otherwise I cannot understand how this camera would move down compared to said slab.

2) Theres an apparent upward, or sideways, movement 12 seconds before collapse, distorting the kitchen pillar. Again I am completely naive to structural issues but I cant think of how this is explainable fully in the current theories.

3) There would appear to be failure of the ceiling above the camera, but nothing obvious (certainly visible) elsewhere in the condo. This seems to be reasonably surprisingly local given the apparent significant building damage already in place by this time, and it is interesting in my view to understand if there is something other than the current leading theory that could cause this.

I get the point though Auri, and I understand there is some lethargy around this extremely detailed video analysis in this thread, looking for colours/objects/shadows/yellow jackets. However, I do honestly think there is a difference between a reasonably static piece of footage which is being assessed to the point of seeing Elvis, and actually looking at a dynamic, internal, piece of footage which shows a progression of events over a period of 12 seconds up to collapse. If this was the 12 seconds prior on the external CCTV, we would be all over it - the clues here are more subtle but I think are still there. In truth I'm a little surprised that there hasn't been more discussion in this thread about this video, as its the single piece of pre collapse objective evidence we have.

I think really key in this investigation is getting earlier frames from the neighbor property security cam vid. If it exists, as it may not have been recording prior to the collapse.

Or other video evidence from nearby cameras.

And whether the columns central to the initial collapse are at a lower level with respect to grade than pre-collapse. That area is cleared, so should be pretty easy to determine. Remove some of the nearby slab and see if paint line is below top of slab level.

And testing structural elements from the debris for strength, reinforcement, etc.

I suspect all of that is on-going, but being kept very private.

So all we can do is wait and speculate. Frustrating.

I too find it very interesting to analyze the 711 ring (or whatever) vid, but that is probably not too valuable in the forensics. We know what happened to 711. Just don't really know what preceded it.

Bizarre that the hired forensic engr is being kept out of the loop!!! That is some BS!!!

Quote (clouditguy)

Therefore, what is the event that wakes up the camera 12 seconds before complete collapse?

This is mostly hypothetical, the precise details may vary.

Pool & patio deck fails. The 9.1 column line (particularly K,L,M) are fatally damaged by that, but do not instantly collapse, temporarily surviving in heavy overload. The building is under exceptional stress, cracks are forming and spreading, but it's mostly standing up and hasn't moved significantly downwards yet. The damaged columns are in overload, and the building is doing it's best to redistribute loads around them.

After 5 to 15 minutes, M9.1 has a compressive failure in its damaged section, the remaining concrete at the damaged point explodes with a BANG! The bang sends a jolt through the entire structure (particularly everything adjacent to M9.1, like the camera in 711), causing the empty TV box in 711 to tip over and the room to deform, activating the camera. M9.1 slowly descends as its now empty section of rebar cage buckles and the surrounding structure is unable to take all of the load. That stress adds up until L9.1 is similarly overwhelmed, probably failing with the SNAP before the final rumble at the end of the video (note the high velocity rock flying from the L line on the left of the room across to the camera on the right, simultaneous to the snap). K9.1, already damaged by the patio collapse, fails almost instantly.

With 3 adjacent columns gone, I9.1 and N9.1 are just moments behind them, and the I–N8 columns rapidly follow. There's a very brief delay at the 4 line on the north of the corridor, probably from the eastern stairwell shear wall. That shear wall also saves the eastern end for a few terrible seconds, but it's already badly damaged and off-axis to the west.

Hypothetical, as I said, fitting what I believe is a plausible damage and failure sequence around the evidence. The exact details will vary; e.g. maybe N9.1 fails slightly earlier than described, due to its close proximity to M9.1. The SNAP towards the end of the video may be from L8 inside unit 711, moments after L9.1 failed in the basement.

I don't want to belabor this because I get the distinct feeling some here think the interior video provides nothing of value (and as non-SEs, we're subject to snipey comments about our background and how we know nothing), but:

Quote (clouditguy)

you see a "pillar" of white at the left extreme. I am pretty sure that this is either the inside of the balcony door frame, or it is a jutting out bit of wall

I tend to disagree. The camera is sitting on some table, and the table has a column attached to it. The column to the extreme left therefore seems like it's part of the table "furniture" and not built in to the unit. I suspect it's a credenza with a hutch top, featuring a little molding where the tabletop meets the hutch portion, like this:

Quote (clouditguy)

This implies strongly to me that rather than "sliding", this table was being "pushed" by this wall.

As for the movement, you can see the gap between the box and the left column decreasing over time, suggesting that this furniture is moving separately from everything else. That could still mean the deforming wall is pushing this furniture (I'm a little suspect of this too - the wall isn't deforming as much as the table is moving by the end, and there's a significant gap between the credenza and the wall), but I'm not convinced the column on the far left side of the frame is actually part of the unit wall or door frame. I'm still of the opinion that the credenza is sliding across the floor at the end due to the floor tilting - and tilting mostly on this side of the column line dividing the kitchen from the living room, explaining why the chairs don't tilt and the box moves (maybe).

Quote (clouditguy)

The 711 video has its safe to say NO events contained within it that are more impactful (to this condo at least) than the event which initially triggered the camera ... Therefore, what is the event that wakes up the camera 12 seconds before complete collapse?

I suspect the cascade of dust was the event that triggered the camera's motion sensors, more than anything else. The box no longer leaning against the wall might have done it, but other changes were probably too subtle. So it's unclear, to me at least, that there were indeed no other events like skewing of the unit, right before the camera turned on. I think the camera turned when the deformation of the unit or whatever event was strong enough to cause enough debris to fall directly in front of the camera to cause it to wake.

Regarding the first frame, it's hard to tell, but there could be a very small amount of debris already on the table surface, indicating the first frame was probably seconds or less before the rest of the video. If so, then I agree that some latency or loss of connection eliminated potentially some movement that happened to cause the box leaning against the wall to be pushed off, and a few moments of perhaps other deformations. This would indicate all the deformations we see happen with one trigger event, right when the camera is woken up, but the camera didn't quite catch everything at the very beginning. Otherwise, the first frame could be minutes before, when a tiny bit of debris was caused by some earlier structural shift, or it could be hours before and there's no debris on the table at all.

That also brings us to:

Quote (clouditguy)

There certainly appears to be a "flash" of light at the top left of the image immediately after freeze, which could be something electrical,

I think the simplest explanation is:
- The camera was in the pitch black taking occasional samples of the environment (the first frame)
- The dust starts falling, the camera turns on, the scene brightens temporarily to account for the increase of white particles directly in front of it
- Then as the camera acclimates, the brightness is reduced again back to normal

I think the flash of light is just a typical camera thing when a camera is enabled and has to adjust for ambient brightness of the room or objects in front of it.

@murph - I think that is a really good interpretation and probably very close to what happened.

The compression of the kitchen pillar could be explained by this as well, as (I presume) if the outer wall lost support at the start, and the slab stayed intact, it's feasible I would assume that the slab pivoted, pushing up on the far end of the room.

The part that still troubles me is the relative movement to the body of the condo in the last two seconds, but your explanation is probably the majority of it certainly.

jbourne8 your mention of column labeled 39/40 in the garage resulted in being able to reinterpret this as an uninterrupted view of the fallen pool deck, but the column is further back in the image. I did lighten and color enhance an image (not remembering now if it’s one I pulled from the forum here or one I took a screen print of from the video). You can faintly see the color of the pool deck tile surrounding that column after this image enhancement, below the arrow. The other image is from the WaPo article, for reference. This is also the correct location for where this column would be seen from this viewpoint.

The column in the foreground labeled for parking spot 27 delineates where the building meets the pool deck. It does appear that the pool deck fell all the way to the edge of the building, before the building collapse. The edge of the pool deck that connected to the building at this location is clearly illuminated on the ground from a light still on in the garage, because you can see the sharp shadow of the broken piece of the deck undeneath it, probably the deck immediately outside unit 111 that was their private deck bordered by the planters. It is located just past column 27, where you would expect it would be. It appears you can then see all the way back to that column labeled for parking spots 39 and 40, behind the fallen planters, partially sticking up through the pool deck tile. This suggests that at this location the pool deck fell all the way from the exterior wall to where it met the building, which would also explain why there are no remaining garage overhead lights in this back part of the garage; we’re only seeing the fallen pool deck. Since it was nighttime there would have been no illumination from the sky, but at this point it is likely there is still some faint illumination of the pool deck from the building lights enabling the view of the distant column.

Admittedly there is a lot of noise in the image so I would not want to overanalyze it, but I was surprised when enhancing the light and color to see that, and felt confident in this conclusion. Also because of the extreme foreshortening in the image it is a challenge to understand the perspective.

clouditguy, many years ago.. I was actually a VOIP technician and I know a ton about the related protocols. SIP is only used to initiate the stream, and most likely it's actually transmitted with something like RTSP instead. It can transmit video and audio at the same time, and RTSP is UDP traffic so there actually isn't much of a delay to it at all (unlike SIP which is TCP). This is why when you're on a VOIP call or transmitting a live stream there is almost no delay at all.. you can really tell when the delay is even 500ms. When I say the delay was about 100ms that was a very informed opinion based on latency across the US (120ms is around the max delay I've seen when going from east to west coast on DSL or better). And UDP streams will never re-transmit.. they'll just drop packets when they lose connection. Even if it's not an RTSP stream, it has to be UDP traffic. I didn't see any jitter in that in the video. In the last 20-50ms or so of it, the video does seem to cut out right before the audio.. but that's the only real difference in delay because of the size of the video vs audio data. It's really not as significant as you think. I'm pretty confident that the stream cuts out as the building is falling due to loss of power. You can actually see a good amount of stuff in the room start to fall towards the camera at the end too (the dust, that black fridge-like object on the right, and the camera itself in the last few ms).

Someone told me that the "freeze frame" is from these photos that the camera takes every hour and was probably started with that "look back" since they don't transmit video when they don't detect something.. it's also in there for several frames and none seemed to be missing. I'm not sure if that's true too, since that's not how my cameras from a similar company work.. but it fits. While it makes since that something could be pushing the table.. the camera also starts to slide to the right in the same manner and at about the same speed, and I find it hard to believe that something is pushing both items in the same way.

I also think the camera was triggered by the failure of M10.1, or at least I made the video with that theory in mind.. to sort of test it. Seems plausible.

EDIT: There is no M9.1? Pretty sure we're talking about M10.1.

Tropmet, I would go watch the video again really.. analyzing the photos from tiktok on their own isn't really as clear - https://www.youtube.com/watch?v=LoNy55PaHlc The first half is the video I grabbed my drawing from too. That thing you're pointing as is probably a white planter, that's sitting on top of the pool deck.

@3DSoftwareDev - great post and thanks for this, as actually some of your thoughts I had also had - and it was your initial analysis that prompted me to finally get off my behind and look at this video in detail which I'd meant to do for days, so thanks :)

I suspect you are right on the flash of light. Clearly in terms of cause/effect, if indeed the first image is a bug/still image, then I 100% concur this is what it is. Perhaps I have tried to make the image fit the theory too much on this specific element.

I do have an issue with the table/credenza thought though, as again this was something I had thought about quite a bit. Couple of reasons. First of all - people. If such a unit (which would even if small be of reasonable size) was in place, the occupant would have placed this unit in front of the large glass doors (or part of them) leading to the balcony. Now my feng shui isnt top notch (!) but this feels like a very odd thing to do. More likely is that this is a much smaller table (or shelf) that is tucked into the corner. Just from an aesthetics in the video perspective also, that far left pillar looks identical to the wall - it looks like plaster not furniture, albeit this is obviously hard to define well. Also, for such an amount of vibration and movement in the room, the camera (an inherently light item) is unbelievably still and consistent in relation to the furniture if not fixed to it. Its obviously not beyond the realms of possiblity that the camera has been secured to the tabletop, but again its not a "natural" thing for someone to do, especially in a $700k condo. The jolt at 7 seconds was significant enough not only to move the tv box, but the three boxes beside - it just doesnt feel right to me that the camera wouldnt move a cm or so if resting. I also dont think whatever it is resting on has any kind of "top" as otherwise the debris couldnt fall as far back as it does (probably).

Perhaps the killer piece - the brighter object to the left casts a shadow from the sensor from the camera. The pillar above does not, which implies it is further away than appears in the video, hence the view that it is the wall or door frame inside angle (that definitely exists in that location in that condo).

Could all be wrong. But all in all I really dont see this being "freestanding" furniture. I also struggle to believe that the box and this "table" would be the lightest two items in that room to move, especially compared to the stools sitting on smooth tile, and the glass sitting on the table.

That black object (fridge?) on the right is also troublesome. It (I think reasonably clearly) starts to develop a gap between the top of it and the wall. That doesnt fit with a downward to the right slope. It would fit with downward to the left, or with a right wall deformity where the top of the wall is moving further to the right - which could(?) tie in with the "bar" to the left of the camera being a wall and also moving to the right.

Feels like minutae detail - and it is. But you are right that if the far left "bar" is part of the furniture not part of the condo then a lot of my interpretation is off. But it just doesnt seem it to me, if it is then actually for me it creates many more questions than it answers (for example - if the room is tilted enough for that table to start to slide, theres no way in my view that the lighter boxes just in front, or the TV, dont start to tip or slide).

Quote (Tropmet)

@jbourne8 half a second delay is massive for humans, I think most people can detect audio delay from video under 150ms without too much issue.

I don't work with audio too much though, I mostly work with stuff where latency must be under 16ms and something like 50ms is considered a long time to me though so....

Keep in mind the very first frame of that external video where the electricity is on will have lasted ~30 to ~50ms, so for ~50ms while it was falling the electricity was still on.

Penagwin, yea.. you're right. I think I got complaints from customers anytime it neared 200-300ms. Any sort of intermittency (different latency times in packet arrivals) tends to really mess up those streams too and makes them hard to understand. That ones nice and clear though.

In that video I made I lined up the ring video so it was about 100 ms before that section lost power, just to see where it would fall - https://www.youtube.com/watch?v=8FNkJrHPBKQ&fe... And yea.. perhaps it's off by 50ms or so, I didn't get that fine tuned really. Getting latency under 20-30ms is next to impossible though btw, unless your company has a backbone directly and is right in the city. I was giving latency times from a typical line that you'd have at home.

Also, the video was only 8.5 fps.. so one frame every 175ms or so btw.

@jbourne8 - thanks for that. Yes sorry I was probably being a little overly simplistic - you are dead right in the SIP/RTSP piece of course.

However, the rest I disagree with a bit, or at least I havent explained myself properly (more likely).

Agree that RTSP can transmit both audio and video. However, more often than not it is split these days as the human sense perception of drops in video vs drops in audio is significantly different, as is the relative importance on audio. In addition, UDP you are right as a Layer 3 protocol does not retransmit. However Layer4-7 can implement retransmit (or more technically appropriate a request for a retry). For a recording video/audio, vs live stream, it is much more likely that a retransmit is built in (although far from nailed on, or even more likely than not, I agree).

All of that said, I'm really not talking about latency or jitter. The issue here is more regarding the packet size which for a given time period would be circa 10x the size for a video packet as an audio one. In a period of RF interference, your larger packets are both more likely to fail their error check on an Ethernet/layer 2 level, and also less likely to be retransmitted at an application layer - the throughput (or more appropriately for this the "goodput" - i.e. data transmitted after overhead) is much higher for video, audio needs very little. So it is feasible that you could lose video feed briefly but not audio basically. This is all to do with local environmentals in the property, not to do with transmission onto the internet.

However - I really dont think it makes much difference to the other elements which are the important ones, and appreciate that it really could be either or. For what its worth, I do believe on balance that this was at least extremely close in time to the "moving" part of the video. Why? The reflections on the surfaces at the back of the kitchen are in the same place accounting for the movement that has taken place (my loose presumption is this is from moonlight entering from the windows behind? Could be wrong), and the happenstance dust right in front of the camera, right where the rest starts to fall, is far too coincidental for me.

@jbourne8

Oh yeah I forgot security video is usually low frame rate. Also I meant the external video, I don't think it's possible to sync the external video to the internal ring video to under 1 frame because we don't know exactly when they stopped/started (We don't know if it had already captured the next frame but not sent it yet).

And yeah packet loss/packet pacing should be more noticeable than just latency alone - that's also why online video games might feel laggy even when your ping looks ok.

@clouditguy

I'm pretty sure the actual ethernet packets sent over wifi are all of the same size? Regardless the audio/video are part of the same packets on that level.

I do know that Layer4-7 will not retry in the context of video/audio, because generally the codecs/encoding are designed to handle it, and latency is far more important then data integrity. (a retry is likely another 100~200ms out, and like we were saying humans would notice that)

The audio and the video are encoded separately and shipped, and like you said the audio needs less throughput so it should be far more resilient to single packet drops than the video, as there's a lot more room for error correction.

tl;dr - audio/video are sent over the same physical packets so it's not that one is more likely to drop then the other. But audio codecs will be much more resilient to lost packets.

You're right that video will be the first thing to go before audio, but we would have to see the original data stream to know either way :/

Worth mentioning (sorry down a rabbit hole around an area of expertise :D) that even at low frame rate you are talking about circa 2MiB/s for that stream assuming a standardish compression to reduce propagation delay. Trying to push that into a "noisy" RF environment over wifi would be a challenge.

By comparison the audio stream would be at the absolute most, assuming no compression, half of that. In reality probably much much less again.

Hence my thinking (albeit I'm going to come back to the real world now as it really makes no difference !!) .

Hey Penagwin

Not to my knowledge. There is a minimum Ethernet packet size of 64 bytes, but otherwise the packet size is protocol overhead + user data. How the user data is defined is another matter of course.

Hmm...cant agree with you re: Layer 4-7. That is solely dependent upon how the application has been coded (albeit I should really say Layer 5 to 7 to be fair), and "latency being more important than integrity" would depend upon the use case. In this case this wasn't likely to be used as a "live stream". It may have been "near" live, but never likely to be live so that immediately puts much greater emphasis on integrity of data (comparatively).

A hugely important factor though which I completely neglected is that as a consumer grade cloud camera recording service (regardless of what specifically it is), the chances of whatever codec or protocol it is using locally being used for actual transport off device is virtually zero. Much more likely it is wrapped into HTTP traffic (therefore using TCP).

We are splitting hairs a bit though ;) myself included, given the increasing lack of relevance to the topic

Quote (clouditguy)

great post and thanks for this

The nice comments are appreciated, thanks!

Quote (clouditguy)

That black object (fridge?) on the right is also troublesome. It (I think reasonably clearly) starts to develop a gap between the top of it and the wall. That doesnt fit with a downward to the right slope.

I actually think it could make sense:
- There's a column visible embedded in the wall, right near this object.
- Perhaps the floor has detached from the column. The floor slab may be sliding down but the column may not be.
- In this break between the two elements, the column takes a little chunk of the floor slab with it, or the floor is generally buckling around where the floor slab previously attached to the column.
- The black object moves "up" because most of the floor below it is now sliding down, but the small chunk of floor slab still attached to the column is not moving down, and that's causing this object to tilt to the left as you suggest, and also back toward the kitchen.

Murph 9000's hypothesis several messages above does a good job (in my non-SE opinion) of tying together the various bits of evidence with a plausible sequence of events.

Murph 9000

I believe, generally, that the failure methodology you described makes a lot of sense.

I have a slightly different take on this however. There is a beam constructed that acts as a transfer beam to support the changed slab level beam. This spans from Col M-11.1 and M-9.1. In pre-failure photos, this beam has appeared deflected. Photos can distort. There is a lot of water leakage in this area. I believe that this beam failed very early on and maybe it took the pool deck with it. If this failure was caused by connection to Column M-11.1 the beam could drop and it could take awhile for Column M-9.1 to fail. This makes sense with the video by the tourist through the parking door. I believe we see M-11.1 on the ground and this beam dropped. Although it is hard to discern.

IF this beam to column connection at M9.1 was compromised due to reinforcing degradation (it is directly below a planter) there could be loss of restraint and, possibly, even loss of reinforcing shear capacity. This could have been a construction error and the plans are not great. This could easily be a beam that was overlooked and was added by hanging from the column instead of bearing on it (the photos look like this could be the case).

This beam failure could cause column rotation and failure of the columns on 9.1.

The question still remains on if there was some trigger that set off a serious construction deficiency in the building as a result of the activities to repair the building.

I did a shoring design of a highly deteriorated concrete column in parking structure supporting a much smaller building than this. We were concentrating on this column, which caught everyone's attention, when I noticed that all of the bar trusses supporting an exterior terrace several bays away were nearly rusted through at the bearing on a steel beam (all hidden by drywall fireproofing that had been replaced unknown to the current building manager). I, honestly, have no idea how that structure was remaining stable. All it would have taken was the forklift removing the terrace pavers to cause a progressive failure of a large portion of the support system. I freaked out and had the building evacuated and the terrace closed. But, it was just luck that I showed up when I did.

As engineers it is a difficult call to close a building during rehabilitation or, even, exploratory evaluation. Where I work, a condo unit can rent for $1000 a night. There is a lot of liability in over-reacting and a lot of risk in under-reacting. I am not saying this is the case with the consultant on this failure. I don't have knowledge of that. Just food for thought.

Based on the dimensions of the room and the likely lens size, there isn’t really a good fit for the camera being up against the wall. The center of the view is almost perfectly aligned with the kitchen pillar, making the camera about 36” off the left wall. The angles of the pillar in the right wall and the corner at the end of the left wall match this, and also puts the camera about 88” from the south wall. The lens is about 110 degrees.

So, most likely, the camera is sitting on a table set a few feet in from the window.

Feel free to post an alternate combination of distances and field of view.

I'm still struggling with the "Ring" video sliding to the right too, so tossing out a new theory that the table didn't slide to the right, but was pushed forward/possibly rotated by the exterior buckling behind it and bowing inwards.

@CE2537: If the post above yours, that the camera is 36" off the left wall and 88" off the south wall, is even remotely accurate, I don't see this theory holding up. I tend to agree with the positioning assertions that this credenza/furniture is not pushed up against either wall, so for the wall to push the credenza, it would have to deform a tremendous amount to bridge the gap either to the left or behind.

It does seem odd that the credenza would be so far away from the walls, but there are all sorts of items in here in unexpected locations. Note the couch pushed right up against the back of the chairs, for example. This unit appears to be dormant, so furniture placement may be more about temporary storage and wouldn't necessarily follow a "where the average person places furniture" paradigm.

Also, there's no indication that I see from the interior video that the table or camera has changed angle relative to the south wall. It moves almost exclusively right (and down relative to the kitchen, if you look at the cropped GIF in the middle of the thread). In the first frame-last frame GIF near the top, if the camera angled relative to the south wall I think you'd see it pretty clearly (but I don't).

To be honest 36" off the left wall would tie in perfectly with my original thought of the table or whatever resting against the internal angle of wall or the inside of the balcony door frame

Quote (hochhaul)

I don't see spring loaded doors. It appears that the scuppers were no more than 5" above the top of the gravel/flood coat.

The detail drawing just below noted as curb detail at stairwell #1 with the spillover door. They don’t open until the water level is near the top of the opening which puts the depth at door around 8”. As the slope is in the opposite direction, Approx 10” is correct. This type would be required around the roof perimeter and UPH balcony above the pool deck and patios as it’s not allowed to have open overflow scuppers discharge unguided to common areas below.

Unless…

They are directed to a green roof with splash re-enforcement and adequate drainage. You just solved the mystery of why the planter areas were revised the way they were. Bravo.

One curious thing about this collapse is that there is the North building which has some identical features, one of which is the column layout in the critical collapse area. A lot of us have looked at the tic toc video to try and understand better the collapse of the pool deck and supporting columns and how that preceded the collapse of the building. Below is a comparison between the north bldg columns and the south building along with views down the respective ramps. the north building view is from google street view and the south is from the tic toc video. This may help in looking at the tic toc video and trying to determine where the columns should be located and what damage they may have sustained in this early failure before the collapse. The column that appears to be missing from the south view is circled in the plan views in red.

Ok so I chanced upon this which could be useful especially for those of us looking at the security camera footage.

https://my.matterport.com/show/?m=4USu8mRgGim&...

This is a virtual tour (with measurement tool) of 611 - the exact same condo the floor below.

I find it particularly interesting that the gap between the west wall and the balcony doors is virtually exactly 36".

Given the imagery in this video, this pretty much confirms for me that whatever the camera is sitting on is flush with the wall.

jbourne8 no, it is too large to be a planter at that distance. It is the column.

Possible initiating event to look at.
Failure starting at the pool slab construction joint after 40 years of failed waterproofing - corrosive chlorides concentrated through a pathway directly to top layer of reinforcement (that were under tension) corroding each of the rebars until the slab finally failed... starting the cascade of the events leading to the complete collapse of part of the building.
TOP layer of reinforcement appear to be closely sheared off along this construction joint.
.

Has anyone noticed in this YouTube video that the column in front of the camera, and the column line further from the camera, are not aligned?



Is this shown on the plans? I don't recall seeing a grid misalignment like this, but maybe I missed it. If so, any idea why it would be misaligned?

Quote (3DSoftwareDev (Computer)15 Jul 21 18:49)

Yes they are on the DWG and the smaller further away columns do not support the building, they were supporting the pool deck.
.

Quote (@ GPR_Tech)

Agreed, that construction joint looks bad. It looks to me like the top reinforcement was terminated at the joint. There are possibly bottom bars, which look they were laying on the form work and not chaired up. No dowels, construction joint was not roughened. I saw a picture of the lobby deck at the south wall and it looked poorly constructed as well.

Quote (tmwaits1 (Structural))

Below is a comparison between the north bldg columns and the south building along with views down the respective ramps.

That shows that the ability to see even the base of the far perimeter wall from the street from a standing position is questionable (blocked by beam) assuming the fallen deck is not also in the way. I was wondering if the people that took the video were sitting by their pool and lower and have a deeper view. I am not confident the back wall is what people see when they talk about the tictok image. I have seen several references to it.

GPR tech - there seems to be a lot of reinforcement missing from that joint. In addition to top and bottom reinforcement, there was also supposed to be a #4 dowel at every 2 feet, right in the middle. Can't see any of it in the photo. This does seem to be good evidence of deficient construction (not conforming to plans or best practices). May be more of that to come based on the field investigations.

tmwaits1, the north building isn't quite identical in that area btw. If you watch the north and south tour videos, they seem to show a different layout for the beams and the step down to the pool deck.

Tropmet, it is definitely not too large to be a planter.. also, no column exists in that location, but a planter probably does. You might want to review old posts, since this was already discussed to death and I drew in the column locations using perspective based on both ratios and the north building and they both lined up at the same spot. It's probably around part 4 or 5.

clouditguy, correcting the technical information about the camera seems a bit pointless, but I highly doubt this camera was sending two RTSP streams. I've never heard of any company doing that, and it would only make it more troublesome for the app to try and sync the data as it would have no real data on when it was sent, only when it was received.. so you'd then be stuck fixing your videos manually. This camera is pretty dumb and I'm confident it was only sending one stream.. but it is possible for it to only send video or audio down that one stream if the other part isn't available. The delay would still be about 100ms regardless of how many streams it's sending anyways. If the other end is in Florida it could even be substantially quicker.. that's more of an average going across the continental US. Keep in mind too.. this isn't 1080p or higher. It's 720 and 8.5 fps.. that isn't much video to send really. The total size of the original video from twitter is only 816k. If this wasn't how video worked, you'd be able to feel the delay in your video calls.

The user said it as recorded at 1:22am, so it happened within a minute of the building collapsing.. and after the tiktok videos were taken. If the 911 calls are a good judge of exactly when the building collapsed (the last one I posted of the 45 min transcript gives the seconds of when someone called at 1:21 and you can hear it collapse), it was right at 1:22am. But yea.. I don't see the point in discussing this one that much really, how I synced them up is off by a second at most.

I think it's really odd people can't see the camera slide to the right too.. maybe you guys are viewing it on your phones?

Someone posted the ring video on youtube and enhanced the audio yesterday.. kind of interesting - https://www.youtube.com/watch?v=gFRWvCAFMYc

@jbourne8 - I think we have crossed wires on this as this isn't really what I'm talking about. But it's really not relevant so no worries :)

Quote (jbourne8 (Computer))

I drew in the column locations using perspective based on both ratios and the north building.....

I can't recall this being done in the vertical plane. Maybe I missed it. I have see a 2d view from above that projects a view projected onto the floor plan. The problem is knowing the height of the camera.

Promise this is my last "ring" vid post. Just watched jbourne8's enhanced video. I got a sense of side to side shaking (like an earthquake) instead of leaning one way or the other. The other thing that came to mind is if you're in a train or subway, you can see the cars in front of you moving left or right before the movement gets to you. I tried to line up the the left corner wall at seconds 7, 11, and 12 in the video - and at least based on this exercise there appeared side to side movement

Wow, a different building in Florida had a roof collapse today - https://www.nbcmiami.com/news/local/portion-of-apa...

"Crews are responding after a part of the roof of an apartment building in northwest Miami-Dade collapsed Thursday. The building is located at 17350 NW 68th Avenue."

Tmwaits1,

I see the difference. Those 12x16 columns are rotated 90 degrees. To be honest, if a car hits a 16 inch column its going to be much stronger then a 12 inch column.

The columns in south should have been rotated like North. They would clearly have been stronger in this direction. Perhaps they learnt their lesson after south?

I think its a clear design error to have those columns rotated in that way. Once you see it, you can't unsee it too. Why?

Quote (jbourne8 (Computer))

Wow, a different building in Florida had a roof collapse today

Interesting coincidence.... or this is Miami-Dade? Pretty soon they won't be able to find enough engineers to keep up with emergency inspections. Lots of hysteria.

Coincidentally the building from today's roof collapse was built in 1982. Far from the beach.

Noticed something today I did not notice before, in the Ring video from 711 the particles/drywall dust fall from the ceiling from left to right (from column line K to column line L) - after the slab/column along grid line K initially fails. We do not know how much longer after the video ends the main collapse occurred as the video would end with electricity or data loss - the camera slides to the left at the very end of the video. To me, this appears as if the exterior facade slowly peeled away, I believe this was the same crack moving across the ceiling 611 saw (before deciding to run for her life.)

-W

Quote (AutisticBez)

I think its a clear design error to have those columns rotated in that way.

Why do you think that?

Quote (Jbourne8)

Someone posted the ring video on youtube and enhanced the audio yesterday.. kind of interesting - https://www.youtube.com/watch?v=gFRWvCAFMYc

A LOT of audio signal is lost in that video. It's been made louder, but not enhanced. The original video posted on twitter has the best audio quality compared to all of the reposted.


Has anyone been able to find any post collapse images of the north side of the 8701 property?

Precision guess work based on information provided by those of questionable knowledge

Quote (Demented (Industrial))

Has anyone been able to find any post collapse images of the north side of the 8701 property?

What are we looking for? Damage to 8701 was limited to dust and light debris. Palm trees shielded view of lower collapsing floors. Drone pic day of collapse:

• https://files.engineering.com/getfile.aspx?folder=05905876-08a7-406a-8b80-6

Quote (Demented )

I'm assuming based off of dimensional call-outs for 3'6" and 48" of piles, the 2'2" slab elevation for the parking/basement level, 4" pile to cap recess, and 32" pile cap height.

The simple fact that depths of the piles are called out makes no sense to me.

T.O. Basement Slab (8”) : +2’10

T.O. Concrete Framing Basement: +2’2

T.O. Footing: -2’2

B.O. Footing: = Depth of Pile Cap

T.O. Pile: = B.O Footing +4”

B.O. Pile : As required

Nothing in particular. I'm just trying to understand why there's worry over the columns on both properties along the CCCL.

Precision guess work based on information provided by those of questionable knowledge

Quote (Santos81)

T.O. Basement Slab (8”) : +2’10

T.O. Concrete Framing Basement: +2’2

T.O. Footing: -2’2

B.O. Footing: = Depth of Pile Cap

T.O. Pile: = B.O Footing +4”

B.O. Pile : As required

I thought the basement slab was 9" or 9.5"?



Also *scratches head*


edit: Nevermind. *Bangs head on desk*


Precision guess work based on information provided by those of questionable knowledge

Can anyone clean this video up? Look at all of them down there at 2:52am, 7/7/21.

Link

Quote (Optical98)

Can anyone clean this video up? Look at all of them down there at 2:52am, 7/7/21.

Link

They were digging a trench by hand all night basically.
https://www.youtube.com/watch?v=1O8Ydaegba4

Precision guess work based on information provided by those of questionable knowledge

Quote (Optical98 (Computer)16 Jul 21 01:48)

Can anyone clean this video up?

It's probably an outtake from:
Champlain Towers South Search and Rescue - July 7

SF Charlie
Eng-Tips.com Forum Policies

Quote (Demented )

I thought the basement slab was 9" or 9.5"?

I’ve seen 8, 9, and 9.5” specified along with multiple elevations for T.O. Basement Roof (Slab).

Regardless of that elevation value, T.O Footing is -5’0 from there, with B.O. Footing as specified per pile cap depth.

We’re working on 3d Models to map out as built incorporating all the individual unit changes where applicable to aid in reconstruction. Having viewed the full footage from multiple cameras at 87 Park today, only makes that more difficult and important.

I stumbled onto this tour of the Champlain NORTH building's parkade, might be worth a look. Innermost and a few other columns look bigger and the ramp area does have a strange raised slab for the generator room.
https://youtu.be/QbjRUvCGRXc?t=574

Another partial collapse in North West Miami Date today, looks as if it may be a wood structure in the photo but too far away. Only a three storey building but if it is wood then usually it does not fail suddenly; Things are getting very interesting in Miami Dade area. See previous post by jbourn8.

Who says the wood structure failed suddenly? It could have been failing for months or more. There even could have been plenty of outward indicators.

It fell DOWN suddenly, but that's gravity for you.


spsalso

OK sparky calm down a bit; news said it was re[ported that it suddenly failed. Over what time exactly we may find out later, as far as I know there is no reported video so far.

Definitely looks concrete. Whaddya know, a big cantilever section fell unprovoked https://twitter.com/i/broadcasts/1mnGeadErLoGX?ref...
17500 NW 68 Avenue

Yes a different video shows that it probably is concrete; according to the mayor it had had its 40 year inspection almost 10 years ago which jives with the first report that the building was built around 1970. The 40 year inspection apparently revealed no concerns. Residents have been evacuated. Possibly someone should open another thread on this failure.

Quote (Auri)

Definitely looks concrete.

Definitely 100% wood frame.

I've seen those referred to as either mansard roofs or false mansard. The actual structure is concrete, but this wooden false roof sat on top of it. A lot of times these get added to existing buildings for curb appeal. Could have gotten blown off or just wood rotted away.

"CE3527 [I've seen those referred to as either mansard roofs or false mansard. The actual structure is concrete, but this wooden false roof sat on top of it. A lot of times these get added to existing buildings for curb appeal. Could have gotten blown off or just wood rotted away."

Or the attachments of the wood to the concrete failed. My first attempt at using a quote and not too great. Weather it rotted or just blew away it should not happen and could easily kill people, why was it certified is the question and obviously closer inspection intervals are required. Was the concrete or anchors deteriorated, was the wood rotten, was it a poor design?

Quote (CE3527)

I've seen those referred to as either mansard roofs or false mansard.

Cockloft is much more appropriate for more than one reason.

They are definitely going to require more competent engineers and building officials in Miami-Dade and possibly other parts of Florida. Unbelievable!!

To keep the two events apart and discussions on-topic I have made a new thread for the NW Miami Dade false roof collapse. https://www.eng-tips.com/viewthread.cfm?qid=485365
Not matters of equal importance by any means but hopefully there will be lessons learned from even this.

Quote (Santos81)

I’ve seen 8, 9, and 9.5” specified along with multiple elevations for T.O. Basement Roof (Slab).

Regardless of that elevation value, T.O Footing is -5’0 from there, with B.O. Footing as specified per pile cap depth.

We’re working on 3d Models to map out as built incorporating all the individual unit changes where applicable to aid in reconstruction. Having viewed the full footage from multiple cameras at 87 Park today, only makes that more difficult and important.

I think what will be found is the piles don't go down nearly what is thought.

All I find are 3'6"and 48". Precast 14"x 14" or as drawn to scale, 13"radius, and 50 tons.

You're not driving 42' or 48" long piles to 50 tons that shallow unless you're. constantly back filling with sand, rock, dirt, wood, rebar, someone's hardhat as a joke, etc.

I still haven't found anything else that calls out dims for the precast piles.
We've seen the other construction flawns. Hell, that odd 2" section in places on the core drills can easily be explained by the drawing issues.

Fuckin typos man.


Precision guess work based on information provided by those of questionable knowledge

Hi Demented

Those depths you mention refer to the pile cap itself.

Pile depths - Given the 'bulb' at the bottom of the pile (shown on the drawing), this would indicate that these are driven, cast in-situ piles (Franki). Crudely explained, a steel tube (more or less 20" dia) is driven down until it reaches a point when the displacement of the tube is minimal (probably down onto the limestone). They then anchor the tube to the piling rig and continue dropping a hammer inside the tube, now displacing a dry concrete mix placed in the tube, to create the bulb. A rebar cage is dropped in and concrete or grout is poured in. The steel tube is then pulled out.

Where they call off 'tension' piles, they ensure that the reinforcing cage is linked into the bulb forming an anchor.

These driven piles are usually quite reliable and shaft stresses are quite low (limited to around 800PSI).
Settlement of piles would show up as differential settlement between columns and be noticed long before a collapse. Safety factors on piles is quite generous.

another-florida-building-evacuated-over-concrete-safety-concerns

Keith Cress
kcress - http://www.flaminsystems.com

Quote (w-streng)

Hi Demented

Those depths you mention refer to the pile cap itself.

Pile depths - Given the 'bulb' at the bottom of the pile (shown on the drawing), this would indicate that these are driven, cast in-situ piles (Franki). Crudely explained, a steel tube (more or less 20" dia) is driven down until it reaches a point when the displacement of the tube is minimal (probably down onto the limestone). They then anchor the tube to the piling rig and continue dropping a hammer inside the tube, now displacing a dry concrete mix placed in the tube, to create the bulb. A rebar cage is dropped in and concrete or grout is poured in. The steel tube is then pulled out.

Where they call off 'tension' piles, they ensure that the reinforcing cage is linked into the bulb forming an anchor.

These driven piles are usually quite reliable and shaft stresses are quite low (limited to around 800PSI).
Settlement of piles would show up as differential settlement between columns and be noticed long before a collapse. Safety factors on piles is quite generous.

I fully understand what the piles should be. I also fully understand ground crew's interperitations of those plans.
Two very different things.


If there is a callout for cip franki, please link me. I can only find precast.



Precision guess work based on information provided by those of questionable knowledge

So, take a look at that North video and I notice the garage looks in much better shape. Very little water issues.

But the first row of 12x16 pool deck columns along 11.1 are rotated 90 degrees. Why? The buildings look very similar. Why the rotation?

If you designed both buildings with similar plans, why would you change this? Think about this, maybe m11.1 is knocked over because its rotated? The rest of the punching shears are 16x16 square. M11.1 is rectangle and the pool deck probably is pulling away from the building. The pool deck forms a "v" between the south wall and the building.

Perhaps in the loss of pool deck, you get M11.1 falling apart rather then punching through due to its flat angle with the direction the deck is pulling it?

Quote (w-streng (Structural))

Settlement of piles would show up as differential settlement between columns and be noticed long before a collapse. Safety factors on piles is quite generous.

Would the pooling of water in parking spot 78 and the cracked garage floor be evidence of differential settlement?

@pellucidar I don't think it's much evidence on it's own, that basement is below sea level (at high tide at least), and with all the known water leaks there's plenty of explanation to how water got there.

Could there still be differential settlement sure, but I don't think the pool of water helps clarify it.

Quote (Penagwin (Computer))

I don't think it's much evidence on it's own, that basement is below sea level (at high tide at least), and with all the known water leaks there's plenty of explanation to how water got there.

Regardless of where the water comes from, it shows the floor is not level. Possibly it was never level, but that would be an odd coincidence (of location).

I was looking at that photo a few posts above that shows the fire department ladder truck rescuing people from the balconies and I was wondering why it was parked way out in the street. Then I remembered there is a garage under that driveway. Probably a good thing the truck didn't drive over it. I'm wondering if they knew or if this is just SOP.

Are the ceilings of these types of underground parking garages normally rated to handle the weight of these big trucks? Google shows a ladder truck weighing anywhere from 36,000 to 60,000 pounds.

From the outset it seems obvious that the main collapse followed the pool deck collapse which caused instability. What is bothering is that 3 separate reports from 111, 611, 1211 (all above each other) report preceding creaking noises.

• 1211 (below top penthouse) 20 hours prior to collapse Elena Blasser heard creaking which woke her up.
• 111 (Ms Nir) heard banging noises which continued to the point where she believed the wall above her was collapsing. She went to enquire at reception and then only saw the pool deck level collapse. Ran back, got her family and when reaching Collins the main collapse occurred.
• Unit 611 woken by noise, saw cracks appear in wall and got as far as 2 flights down prior to collapse (time line here not really saying much).

Could there even have been a trigger at penthouse roof level? Maybe punching shear at the penthouse roof slab (K8 or K10) which then left the roof resting on the cmu of the apartment 1211 below. After some time this load may have transferred into the cmu below and this deflected and transferred through the very thin 8” slabs until reaching the ground floor slab. This then overloaded the ground floor slab and caused a localised collapse (tik tok), spreading to the podium area. A few minutes elapsed whilst the loads were redistributing to surrounding columns until overload was reached.

There really could be so many scenarios. They may even have the video evidence showing exactly where the failure mechanism started, thus explaining the apparent gung-ho debris removal.

Parking garage floors are typically sloped for drainage. There are drains at the low points to collect water. It's hard to keep water out of them. But they need to be maintained, cracks sealed, toppings replaced, etc. Based on the videos of the garage ceiling showing rust, cracks, and peeling paint, one clear source of water intrusion into the garage was from above, but it could come from groundwater below, openings like the entrance ramp, and through retaining wall cracks. The report shows pictures of cracks at the ramp down to the garage (area is highly exposed to rain and water blown in), but I don't remember seeing much in the way of cracks showing differential settlement at the actual garage floor slab. I think the water on the garage floor was a symptom of the porous ceiling above rather than a cause.

Jedidad

Underground parking garage roofs should be designed for anticipated loads. The code, in my experience, is a bit vague when it comes to what loads these structures should be capable of supporting when they are outside of buildings.

I was involved in the evaluation and repair of an exterior plaza over a parking structure. Very similar to the situation at Champlaign South. The terrace was showing signs of damage to supporting beams...in this case steel due to de-icing chemicals and a poor membrane flashing install.

Somewhere after the terrace was constructed the fire department decided that this terrace was a “fire lane”. The building adjacent to it was an 8 story hotel/condo. They decided to do a training session and had a fire truck on it. The plaza was not designed for this and by shear luck the loaded outrigger ended up on a beam.

The original designer of the building had no idea this area would be used for rescue operations. I designed additional supports and we built permanent barricades that limited vehicle travel locations.

My long answer to your short question is that sometimes we consider these loads and sometimes we don’t. But we should.

Quote (w-streng)

What is bothering is that 3 separate reports from 111, 611, 1211 (all above each other) report preceding creaking noises.

• 1211 (below top penthouse) 20 hours prior to collapse Elena Blasser heard creaking which woke her up.
• 111 (Ms Nir) heard banging noises which continued to the point where she believed the wall above her was collapsing. She went to enquire at reception and then only saw the pool deck level collapse. Ran back, got her family and when reaching Collins the main collapse occurred.
• Unit 611 woken by noise, saw cracks appear in wall and got as far as 2 flights down prior to collapse (time line here not really saying much).

At the point when 111 and 611 heard creaking noises, the building was already in the process of collapsing; for 611 it was imminent (<1 minute).

For 111, it’s no wonder the noises were coming from above. There was 12 floors of load being redistributed throughout the building surrounding them. Even at the onset of the start of the progressive collapse of the slab outdoors, the mass of the building (columns and beams) is what was transmitting the sounds.

w-streng, Along the lines of your theory, the Post Roof Anchors for the Penthouse appear to be located on top of the PH roof slab directly over columns. If this area of slab was under nourished for punch shear as the patio deck to column interface appears to have been. It seems very logical that any activity in this area of PH slab, whether drilling and testing Hilti-Adhesive Anchor bolts, or perhaps repairing damaged concrete, or performing OSHA certification test of installed post anchor assembly in these areas would be very risky, now that we know patio deck was under nourished, and there was lots of water leaking in garage and lots of water under 25 year old build-up roofing. Further could they have damaged rebars in this area installing anchors or core drilling. We see from core samples they were able to center core drill directly over rebars.......

Edit: Plus all the rain that had fallen and was sitting on patio deck slab and roof. Were roof drains clogged?? There does not seem to be lots of non-cosmetic maintenance going on....

???

warrenslo, you are up!

Yes, drains were clogged and water was pooling on the roof above the collapsed locations, as well as others. ILl find the images later

Precision guess work based on information provided by those of questionable knowledge

Quote (Spartan5)

Quote (For 111, it’s no wonder the noises were coming from above. There was 12 floors of load being redistributed throughout the building surrounding them. Even at the onset of the start of the progressive collapse of the slab outdoors, the mass of the building (columns and beams) is what was transmitting the sounds.)

I don't disagree and can't stand conspiracy stuff, just trying to make sense of the time lines and exploring options. When 111 was hearing noises the pool slab seemingly had not collapsed yet. But maybe it had already started elsewhere.

Quote (Colostruct)

Underground parking garage roofs should be designed for anticipated loads. The code, in my experience, is a bit vague when it comes to what loads these structures should be capable of supporting when they are outside of buildings.

They need to be designed for human error as well, including humans being unaware that it's a roof and/or signs being obscured / missing. There was an example in Quincy, MA not so long ago of a loaded dump truck (a big one, probably 60,000 lbs to 80,000 lbs gross) driving across a garage roof at a medical building, and falling through it.

In this collapse, one of my hypothetical triggers is something like a 14,000 lb F-350 backing over the surface parking to the planters. It was a wide enough entrance, and something like 8 or 9 foot headroom. E.g. something associated with the landscaping, ongoing construction, the core cutting, or any other service truck. It doesn't have to be an instant collapse, just do enough damage to start the countdown. I.e. potentially fatally crack it at noon, thermal contraction at midnight finished the job.

If your anticipated loads are passenger cars, but heavy trucks can still physically fit, you have an accident waiting to happen. You also can't rely on the valet or security guard to enforce cars only access, as they can be on a break or the new guy who didn't know.

Murph 9000

I'm just a one to two man structural engineering firm. In my limited experience, I have seen vehicles on terraces (or almost on them) half a dozen times. Recently, I designed a residential parking garage for a mixed use building that had living space below. I showed up one day and a trailer full of bags of mortar was backing up onto the slab (the structure had yet to be enclosed). My design of the floor system was well above code because parking structures scare me a bit. But, still this vehicle would have tested that system.

I've witnessed, a number of times, fork lifts moving pavers around terraces when pavers are being replaced. The wheel loads of a fork lift can well exceed the code loading for these systems. Looking at the terrace slab design for the Champlaign Tower, I have my doubts that this pool deck was designed for any sort of substantial vehicular loading. And, high end clients HATE yellow painted barriers at entrances to terraces. So, even signage and barricades at the initial construction might not stop theses sorts of loads.

This is a judgement call. Should you assume every access point to a building that COULD have a truck on it be constructed for this loading? And, what sort of truck do we consider? A concrete mixer on a parking structure could be a huge additional expense. I've designed for this when I felt I couldn't keep a truck away from a structure and no one was happy with me with what it cost to do it.

Quote (w-streng)

I don't disagree and can't stand conspiracy stuff, just trying to make sense of the time lines and exploring options. When 111 was hearing noises the pool slab seemingly had not collapsed yet. But maybe it had already started elsewhere.

The pool slab probably didn’t collapse in unison all at once. It was likely a slow progressive failure too.

Say the slab just gave up, maybe along the construction joint. It may have started with one piece of corroded rebar that gave; pop. Then another with more load now; POP. Then another with even more load; BANG. Then the slab starts to fall; BOOM. First onto cars maybe. Then areas where no one is parked (even “louder” and more pronounced of a crash).

All of this “noise” would have been transmitted through the structural members of the the building. The floor being covered with insulating flooring materials (possibly/probably) vs the ceiling and walls which are exposed.

What 111 didn’t appear to hear was parapet wall and AC units slamming into the concrete at 70 MPH outside of their unit.

Quote (warrenslo (Structural)13 Jul 21 04:48
Well lookie here, KCE is drilling to the ... Penthouse... boom...)

I would read nothing sinister into this.
floor drilling: I would suggest that he is trying to build a feel for the concrete strength as well as the make-up of the floor to determine the loads. During construction they would need to have raised the penthouse finished floor level above the roof level to stay out of the water.
Column drilling: These are the least loaded columns, makes sense to test here.

Quote (Spartan5 (Civil/Environmental)16 Jul 21 17:18
What 111 didn’t appear to hear was parapet wall and AC units slamming into the concrete at 70 MPH outside of their unit.)

Oh dear, not you too.

Edit: Misunderstanding, my bad.

Spartan,

I think there’s a flaw in your theory but I may not be fully understanding the timeline you have in mind.

Two issues:

First, prior to the pool deck collapse, there should not be ANY weight distribution going on, if the pool deck was the trigger. So the prior day’s noise complaints from 1211 still need an explanation.

Second, between the pool deck collapse and the main collapse, what type of weight distribution could be going on above, that was not also causing problems in 111? If the shape of 111 was compromised or otherwise wasn’t holding its weight, wouldn’t we have heard instead that the floor was buckling, or the windows were cracking, or something like that? How would 111 be intact, while floors way above it are actively shifting onto different columns?

I’m struggling with how a pool deck collapse could cause remote weight shifting without much more obvious issues nearby, at all times during the collapse. After all, the final collapse wasn’t upper floors moving around, but lower floors giving out.

Not me too? I said they didn’t hear it. As in it didn’t happen.

Quote (Js5180)

So the prior day’s noise complaints from 1211 still need an explanation.

Coincidence? Older people hear things and don’t sleep well? (I know, ageist, but it happens to me too).

What people in any of the upper floors didn’t hear, or report to have heard, or escaped because they heard; was any part of the building’s upper levels collapsing. Why not?

Quote (Js5180)

Second, between the pool deck collapse and the main collapse, what type of weight distribution could be going on above, that was not also causing problems in 111? If the shape of 111 was compromised or otherwise wasn’t holding its weight, wouldn’t we have heard instead that the floor was buckling, or the windows were cracking, or something like that? How would 111 be intact, while floors way above it are actively shifting onto different columns?

Theres not much “between the pool deck collapse and main collapse.” 111 heard the noises. Went to complain. And then got the hell out of dodge.

The progressive collapse of the slab built slowly built to a crescendo as more and more gave up over several minutes, maybe longer. That was what I was describing. It wasn’t until that progressed to the point that it impacted the building columns that things got grave.

The yielding of the columns, gross distortion, and subsequent final collapse of the building took place over a minute at most probably. 111 was on their way out of the lobby at that point.

I was not implying any sinister. The plates on the post anchors are like 14-16” square. Those PH columns are small. Holes for plates are at outer edge of plate. So if plate centered over column, then holes drilled are near edge of column. In the collapsed patio deck, there appears to have been rebars near edge of column. If PH roof same scenario, anchor drilling for centered plate might get rebars near or at column edge providing either negative moment or some shear support? They were to scan concrete before drilling. Maybe they did or did not??

I just want to confirm some logic:

The people who came up the garage elevator into the lobby and walked into a cloud of dust and noise, they witnessed the collapsed slab and sunken cars in the exterior surface parking area adjacent to the lobby, correct? As far as I know, they did not state that they witnessed any collapse inside the garage before stepping into the elevator (besides hearing some weird noises). So the logic I am inferring from this sequence is that the collapse in the garage documented by the tik tok video could not have PRECEEDED the collapse of the surface parking area near the lobby, or they certainly would have noticed it before getting on the elevator. The tik tok area collapse must have either been at the same time or subsequent to the surface parking area collapse.

I feel like this distinction is important when thinking about what part of the plaza slab may have failed first. But is this logic sound or is there a flaw I am missing here?

Quote (Thermopile (Aerospace)16 Jul 21 17:47
I was not implying any sinister. The plates on the post anchors are like 14-16” square. Those PH columns are small. Holes for plates are at outer edge of plate. So if plate centered over column, then holes drilled are near edge of column. In the collapsed patio deck, there appears to have been rebars near edge of column. If PH roof same scenario, anchor drilling for centered plate might get rebars near or at column edge providing either negative moment or some shear support? They were to scan concrete before drilling. Maybe they did or did not??)

I quoted warrenslo, not you! Sorry for the confusion.

Yes, I am uncomfortable with the PH support too. These edges (and others) are not comforting at all.

w-streng, Agree. It is like because PH roof only 6” slab, they put columns at outer edge of cantilever to let 12th floor cantilever handle PH cantilever and double parapet walls in that area. PH bootleg addition

Just from a logic standpoint about the roof/ac theory, what seems to be getting suggested is that the roof structure was so incredibly flawed that a few holes in a column or some 100lb rolls of roof material caused it to collapse, but that the 12th floor structure was so incredibly strong that it withstood the massive impact of the falling penthouse roof slab.

And as I remember PH cantilever roof projected out further into space than 12 floor cantilever and parapet.

Quote (CE3527)

Just from a logic standpoint about the roof/ac theory, what seems to be getting suggested is that the roof structure was so incredibly flawed that a few holes in a column or some 100lb rolls of roof material caused it to collapse, but that the 12th floor structure was so incredibly strong that it withstood the massive impact of the falling penthouse roof slab.

I'm not sure "suggested" is the right word as much as it is "assured" by some posters when it comes to those defenders of the "roof-first" theory. And their theory is that big chunks of roof/penthouse fell (apparently with a convenient delay from when the culprit roof anchors themselves were actually installed), and spectacularly blasted through the pool deck slab like a kill-shot.

Quote (Thermopile)

The plates on the post anchors are like 14-16” square. Those PH columns are small. Holes for plates are at outer edge of plate. So if plate centered over column, then holes drilled are near edge of column.

That would certainly explain this photo posted a few days ago...could have missed the column completely.

• https://files.engineering.com/getfile.aspx?folder=ff41b8c9-e638-41e8-ac7f-b

The roofing repair permit was released titled "8777 COLLINS AVE PERMIT # 21-211-APPLICATION" from https://surfside.one/public-records-search/

I'm not sure if it's interesting or not, it cost them 1.3mil

• https://files.engineering.com/getfile.aspx?folder=2e4a91d1-fbb7-4be0-b693-0

Quote (arbitraria )

That would certainly explain this photo posted a few days ago...could have missed the column completely.

I’m not uncertain that’s part of a Rooftop Equipment Hurricane Stand or the machine room stairs, not a posted fall arrest anchor.

...no longer live, but I started watching over again from the beginning, I may be confused, but it looks to me like they are excavation below the garage floor?
Watch Live: Champlain Towers South Recovery - July 15

SF Charlie
Eng-Tips.com Forum Policies

Quote (bones206 (Civil/Environmental))

I feel like this distinction is important when thinking about what part of the plaza slab may have failed first. But is this logic sound or is there a flaw I am missing here?

Sounds pretty logical to me. These people are key witnesses to the progression. Unlike nest, they can describe what was going on around them at the time. If they can recall accurately.

Quote:

and spectacularly blasted through the pool deck slab like a kill-shot.

Not only blasted through the pool deck, they turned back under the building and knocked out the building columns.

Quote (Thermopile (Aerospace)16 Jul 21 18:39)

And as I remember PH cantilever roof projected out further into space than 12 floor cantilever and parapet.

Above still is grabbed from this 4K pre-collapse drone footage:

https://www.youtube.com/watch?v=VM416Xg-oBQ

I too am puzzled by the timeline with the folks coming up out the garage to the lobby. Come up the steps, get in elevator, ride elevator up, alarm sends elevator back down, arrive back in lobby to heavy dust. Maybe that dust was from the patio collapse. But reading other accounts, it sounded like they exited the elevator and exited the building right as the building collapse began.

So where does the few minutes between patio collapse and building collapse fit in with what this crew saw? Presumably the garage collapse as seen in the tic tok vid had not happened yet while they were in the garage.

SF Charlie - I'm still thinking no on the slab on grade removal, but my only real basis is I think the water would be muddier and the small skidsteer wouldn't be gliding across the exposed subgrade that easily. The portion of what appears to be an elevated slab (just above the skidsteer) in the beginning of the video is interesting to me though, not sure why they seem to be preserving it, at least for the time being. Best guest: personnel access from top side to pit, I see the rope there.

Quote (bones206)

I feel like this distinction is important when thinking about what part of the plaza slab may have failed first. But is this logic sound or is there a flaw I am missing here?

The story is that they were not going to the lobby, but that the elevator was on the way to a higher floor and then it was automatically recalled to the lobby and they got off once it arrived there. So, they were on the elevator when the deck starting collapsing.

The surface parking area fell into the garage below. Would they have been in the parking garage after part of the garage roof had fallen in without noticing???

Quote (LionelHutz)

Not only blasted through the pool deck, they turned back under the building and knocked out the building columns

How could I forget - the sentient parapet hell-bent on destruction.

I'm afraid it's a debate that won't be solved on these boards.

In looking at the CCTV surveillance video, one faction of posters sees an already-collapsed upper two levels of the building, while the other sees the central building stack intact, with the collapse already in progress to the tune of about two stories worth of fall. I feel like the latter interpretation is more likely, based on what is actually visible (the video quality is awful) in conjunction with some fairly obvious pool deck-level Achilles heel(s).

Spartan5 put it very succinctly in referencing Occam's razor. I land squarely in this camp.

No doubt when whatever NIST report is filed and made public, there will still be those select few who won't believe it given how invested they are in their theory. Flair for the dramatic, I guess.

I saw a frame in the video with the 2 rather distinct looking upper level parapets about a story or 2 down already but definitely there. Small pieces could be missing, but not the whole parapet section. I don't know how anyone can argue otherwise because I didn't try very hard, at all, to analyze the video and still saw that within a few seconds of looking at it.

At this point, these threads are just going around in circles with new members injecting their "new" theory even though it was previously posted and often with some previously known or posted facts being ignored.

Ok, PH has larger outside deck, but still roof projections all line up.

New live stream started at https://www.youtube.com/watch?v=Wl7xiMcYpQQ

Highlight so far is a guy attempting to corral water with his mini track loader.

Would someone like to start a new thread? I’m mobile at the moment but I have something fresh/interesting to share to kick it off. It will be a good start to the weekend for everyone.

I haven't tried to follow all the details of the top-down vs bottom collapse. But I can't help but wonder if somebody isn't thinking "Hey, if we can make it (partially) the fault of the contractor working on the roof, we can go after their insurance, too!"

Quote (Spartan5)

Would someone like to start a new thread? I’m mobile at the moment but I have something fresh/interesting to share to kick it off. It will be a good start to the weekend for everyone.

Done.

All- please shift your responses to the new (#7) thread.

Edit: moved to 07.

*********************

Quote (bones206)

So the logic I am inferring from this sequence is that the collapse in the garage documented by the tik tok video could not have PRECEEDED the collapse of the surface parking area near the lobby, or they certainly would have noticed it before getting on the elevator.

Quote (mechinnc)

So where does the few minutes between patio collapse and building collapse fit in with what this crew saw? Presumably the garage collapse as seen in the tic tok vid had not happened yet while they were in the garage.

The timeline and 911 call timestamps are helpful in understanding what we currently know about this. Nicolas Vazquez's statements are difficult to evaluate by someone who does not speak Spanish and are subject to future clarification. ​

This is my understanding. Everything was happening very fast at that moment. Adriana Sarmiento's TikTok video starts after the Vazquezes got out of the garage. So her video is showing us what the garage entrance looked like right after the deck collapsed. By that time, the Vazquezes were up in the lobby with the Nirs.

• <1:15 am: Vazquez/Accardi drive back from dinner, park in the garage, walk to the elevator, hear a weird cracking sound, get on the elevator
• ~1:15 am: Deck collapse, witnessed from the lobby by Sara Nir from 111 and Shamka Furman, security guard
• 1:16:27 am 911: "A big explosion" "earthquake." This call may be from Shamoka Furman
• <1:16:39: fire alarm directs elevator to lobby
• 1:16:39 am 911: Central Alarm Control calls in fire alarm.
• >1:16:39: Vazquez/Accardi exit elevator into smokey/dusty lobby, hear car alarms, see "sunken cars", and run out of the building with the Nirs just before the building collapses. In one interview, Vazquez said their entire experience occurred in less than five minutes. Sara Nir said that the building collapse just as they crossed Collins.
• 1:17:49 am 911: "earthquake" "the garage" "something underground... everything exploded down." *May also be Shamoka Furman
• 1:18 am: Adriana Sarmiento begins to video the rubble seen in the garage entrance.
• 1:22 am: Building collapses.

What I am still baffled by is what Sara Nir heard at 1:10 am. She said it sounds like a wall collapsing. All three Nirs said in multiple interviews there were three collapses preceded by the knocking sounds (which Chani Nir says were already happening at 11:00 pm):

• 1:10 am: Sara Nir hears what sounds like a wall collapsing
• 1:15 am: Sara Nir and Shamoka Furman witness the deck collapse
• 1:22 am: All witness the building collapse

Heads up, migration to the new thread is just a click away...

Miami Beach, Champlain Towers South apartment building collapse, Part 07

After seeing pictures of the condos and how lavishly they are decorated and trimmed out, there certainly was no evidence of that digging thru the rubble.

I didnt go back thru all 6 threads, but has there been any talk how easily the concrete crumbled, even with just hand tools? A product of it collapsing? Carbonation? Sea mist?