In the first frame of the surveillance video, the center of the building had already dropped down 2 to 3 floors. The parapet for the penthouse roof over the middle section of the building appears to be missing while the parapet for the roof of the 12th floor remains. Building on the narrative that warrenslo and Dold have elaborated, I believe that as a result of penthouse roof weakening induced by the recent installation of anchors close to column tops that may have compromised the rebar underneath and the additional load of roofing materials added to the already critical load of air conditioning units, the penthouse roof may have given way at the front causing the parapet for the penthouse roof over the middle section of the building to crash down behind the parapet for the 12th floor roof, leaving the rear part of the penthouse roof attached like a hinge. This would have caused the penthouse roof to tilt down at about a 20° angle (see photo). This amount of tilt would have caused some of the air conditioning units to topple over because they are already top-heavy as a result of their motors being near the top of the units and placing them even higher on raised metal frames would have caused their centers of gravity to extend over the footing of the frames. After toppling over, they probably rolled downward into the parapets, crashing through the parapets along with the green bag of roofing materials, and then falling further to the deck below right in front of the three critical columns holding up the middle section building. This would have caused the two columns K10 and L10 to punch through the pool deck, initiating the fall of the center section, which then caused more of the pool deck to fall as a result of the loading from the collapsing building.













If we now look at the frame of the TikTok video that Sym P. le has enhanced,

we see a round object inside a squarish frame near column 27 beside a second rectangular object and what appears to be two portions of a broken column. Sym P. le has speculated that the round object inside the squarish frame near column 27 and the second rectangular object to its right are an SUV (possibly a Ford Explorer) positioned head in to parking space 27 that knocked down the column behind it. SFCharlie has speculated that the round object is a washing machine, and JS5180 that is a ventilation fan. Sym P. le has also speculated that the green object is a planter from outside room 111. I believe that the round object inside the squarish frame near column 27 is an air conditioning unit originally installed on the penthouse roof over the middle section of the building. The color even matches the light color of some of the air conditioning units (see photo below). I believe that the rectangular object beside it may be another air conditioning unit and the two rectangular objects adjacent to it may be portions of the parapet for the penthouse roof. I join with warrenslo in believing that the green object is a carrying bag used by the crane to lift materials to the rooftop that was left on the rooftop overnight (see photo below). I believe that these objects slid off the penthouse roof when the roof tilted as a result of the rebars holding the penthouse roof to the front columns were weakened by drilling holes for anchor installation and gave way later during the night as the weaker penthouse roof was heavily loaded with air conditioning units, anchor materials, and roof repairing materials. This event would have happened before the TikTok video was taken seven minutes before the collapse of the entire building, and probably seven minutes before the entire pool deck collapsed. This event would have caused two loud crashing sounds, one when the penthouse roof collapsed onto the roof of floor 12 below, and one when the air conditioning units fell and crashed into the deck below along with sections of the penthouse roof parapet and the green tote bag carrying heavy roofing materials left on the roof overnight by the workers.

prompted by the Champlain collapse they just closed half the Miami/Dade courthouse for immediate structural repairs.
https://apnews.com/article/business-lifestyle-heal...

Quote (MarkBoB2 (Electrical))

In the first frame of the surveillance video,.....

Really good job on that post. On Round object in tic toc being an a/c compressor unit: not sure but I think I see the fan blades.

Quote (1503-44)

Yes. The fire pumps should have activated when the system lost pressure through the broken lines. The sensors were most likely not flow sensors, but low pressure sensors. Flow sensors might not trigger on a slow leak that might even drain the system after awhile. Pressure sensors don't distinguish between pressure lost due to a sprinkler activation by fire, or due to a broken feed line. Low pressure by any cause activates the alarms and turns on the fire pumps (if there were pumps required in that system, probably so for that height). It seems the fire system should have activated to flood any line breaks, if not from pumps, just by the city water pressure alone.

In residential & commercial buildings, almost always pressure is maintained by a "jockey" pump controlled by a pressure sensor. A second pressure sensor with a lower setpoint activates the fire pump, as you described. The flow switches are usually installed and wired to the fire alarm system, to detect activation of the sprinkler system - but they don't control any pumps.

Generally anywhere with over 20 sprinkler heads needs to have a flow switch, I'm surprised there was not one shown in the original sprinkler plans for the garage. Possibly a code violation, depending on what was in force at the time.

Just wanted to comment with regard to A/C units on the roof(posted by MarkBoB2). I was an HVAC /Energy Conservation engineer. The units on the roof are small units like you would have in your home probably 3 to 5 tons (12000 btu/hr = 1 ton). Codes require them to be bolted down.

Also they are not top heavy, but bottom heavy with the compressor mounted at the bottom, the coil wrapping around horizontally. A small motor at the top of no more than 1/2 hp is on top that weighs about 20 lbs. I just sold the cond fan motor from my 3.5 ton Carrier on ebay.

Certainly all ac units in the collapsed section ended up on the ground.

I find it interesting that MarkBoB2 joined the forum to make that post. Where did all of those images come from? It’s like there’s some parallel world where this roof theory lives that bleeds into this one.

If the roof collapsed many minutes before the rest of the building, where are the panicked 911 calls from floors 9, 10, and 11?

If there was some cascade of debris coming off of the roof onto the ground below, how was it that no one observed this or reported noises coming from outside of the units?

Quote (MarkBoB2)

Building on the narrative that warrenslo and Dold have elaborated, I believe that as a result of penthouse roof weakening induced by the recent installation of anchors close to column tops that may have compromised the rebar underneath and the additional load of roofing materials added to the already critical load of air conditioning units, the penthouse roof may have given way at the front causing the parapet for the penthouse roof over the middle section of the building to crash down behind the parapet for the 12th floor roof, leaving the rear part of the penthouse roof attached like a hinge

You reference a narrative about this roof collapse being built by warrenslo and dold… but I don’t recall seeing anything being said by dold to that effect. In fact, they had this to say:

Quote (dold)

That is interesting. I still have a hard time believing that hammerdrilling 4 ~3/4" diameter holes in the roof slab would cause the balcony/roof slab to collapse.

And

Quote (dold)

I see what you're getting after, but I still find it very unlikely that anything dealing with these davits/anchorposts/whatever, had anything to do with the collapse.

Quote (MarkBoB2 (Electrical)10 Jul 21 18:41

In the first frame of the surveillance video, the center of the building had already dropped down 2 to 3 floors........)

Isn't the view of the TikTok video approximately one column line east of where the AC units and roofing materials would have fell? If your your theory is correct, I think the ac units would be more to the right in the TikTok video???

MarkBoB2, this was already discussed in a previous thread btw. That circular object is actually the C in their gate. Personally, I think all the green objects down there are just greenery from the planters, because that's really the simplest explanation. I think the tiktok video was taken around 30-60 seconds before the surveillance video as she said when she ended it she walked back to her pool to take another video and when she got there the building started to collapsed. This progressed really quickly and a lot could have happened in that time.

Also, your pic of the surveillance photo is mislabled btw.. those lights that are on near the middle of the building must be for the 9th or 10th floor because they're right around where those vertical lines on the building end. It is a bit of a mystery on why the roof and penthouse aren't visible, but they could have fallen down to the 12th or 11th floors in the second before that video starts.

Also, according to that budget doc it does look like they had a security room btw.. they said that equipment was in the Central Recording Station and the photo they seem to show is of a second monitor. If you look at the Israeli 3D models of the site too, it looks like it went through several reconfigurations downstairs.

Quote (Vance Wiley (Structural)10 Jul 21 18:43)

How many units were there? It looks like the last ones sold went for about $700K. What was the square foot each floor?

Here is some recent info, please see attached pdf

SF Charlie
Eng-Tips.com Forum Policies

• https://files.engineering.com/getfile.aspx?folder=ea7661da-f41e-40cb-9260-a

Quote (MarkBoB2 (Electrical)10 Jul 21 18:41)

we see a round object

The round object has already been identified as the garage ceiling ventilation fan.

SF Charlie
Eng-Tips.com Forum Policies

Quote (jbourne8 (Computer))

this was already discussed in a previous thread btw. That circular object is actually the C in their gate.

I think he is referring to the other circular object apart from the gate Champlain "C" . It's been discussed here separately as being possible anything from a washing machine to a truck wheel well.

They also had round tables right next to the planters btw.. could easily be one of those.

Quote (zebraso (Mechanical)10 Jul 21 19:58)

being possible anything from a washing machine to a truck wheel well

Yes, but then someone found a photo of the ventilation fans in the garage, and this is obviously one of them that was hanging from the ceiling right above where it fell.

SF Charlie
Eng-Tips.com Forum Policies

If something fell from the top of the building and precipitated the collapse, that something should be found near the bottom of the debris pile.

spsalso

Part 03

Quote (Js5180 (Computer)4 Jul 21 18:19)

I’m thinking the round object is a ventilation fan, which the plans show as being in that general area.

SF Charlie
Eng-Tips.com Forum Policies

In regards to continuation from Set 04

As I say all the time, Just because codes allow, or better said, do not prohibit a certain design, does not necessarily mean any particular design that meets code is a good idea. This design appears to have deficiencies and in the very least, fosters progressive failure. It may even be effectively unsuitable for use just because of that one characteristic alone. This design also appears to require intensive maintenance, far and above typical levels, especially given the severe environmental stress it has experienced. At the very least, it was not corrosion resistant in areas that it should have been. This design apparently did not incorporate any progressive failure mitigations. There appears to be no good reason why a design that allowed a pool deck collapse to take out 75% of the building was selected. A simple construction isolation joint might have limited damage to loss of the jacuzzi water.

It is also quite typical that codes do not recognise all design flaws, especially those that are still unknown to us as production line engineers faced with new materials, new fabrication and construction methods and what seems to always be more and more stringent economic limitations. Codes typically only cover things that are within our previous realm of collective experience. Seldom will they be adequate when stretching their provisions to the limits, nor exceeding any established practice of the past, maybe even including an architects wet dream trying to make you design your next slab with 2" thick floor slabs and 50ksi concrete. Will you do it if the numbers work based on present code allowables?

Codes change all the time to address new problems that come up as we move forward. Many of which were totally unexpected. We were designing and fabricating high pressure pipe walls with newer and stronger properties, all permissible under our existing codes at the time, only to realise too late that our quality testing methods were not sensitive to discovering laminations in the steel brought on by the new fabrication techniques. Other materials were found to become brittle under lengthy exposure to hydrogen compounds, especially at higher pressures and temperatures. The pipeline design codes were revised. Some materials were deemed unsuitable and prohibited from further use. Others were required to have different quality control procedures, others were required to be normalised by heat treatment.

It is my highly experienced intuition that is now telling me that we will soon see a number of revisions in building design, maintenance, inspection and occupancy codes due to the results we are talking about here today. Even if for some reason we don't, every structural engineer that's reading these now 5 sections will be thinking about how he/she will react the next time an architect or owner says thin slaps, no drop panels, capitals, or beams. If s/he isn't, it might be time to start.

[IEGeezer, No, I have not learned the whistling language Silbo. That is a specific peculiarity of Isla Gomera. Interesting that you know of it. All of these islands are quite different. I'm on Tenerife, la isla de los chicharreros.]

WOW is all I can say about MarkBoB2's outstanding post!

Quote (Thermopile)

it would not surprise me that most of those residential units are NOT tied down.

On the roof of a 12 story building in a hurricane zone?

Quote (Thermopile)

I fully agree Penthouse and perhaps 12th floor in middle fell first. Something woke up the security camera to catch the scene after initial trigger.

That would have happened several minutes before the main collapse. When 111 and 611 were hearing noises before they fled the building. Wouldn’t that have all been captured by the security camera as well?

If I heard the Penthouse roof crash down and got woke up in middle of night, the last thing I would do is call 911.

I would get my ASS moving fast

MarkBoB2, keep in mind that there was no real "accumulation" of A/C condensers on the roof, as suggested in some theories. They had all been there for 40 years, and were present in the original 1979 plans in the same basic locations. Most will have been replaced over the years, like for like, but the general structural load shouldn't have changed much. The only way they are really a major factor is if the penthouse roof was critically weak.

It was the big HVAC for the common areas, on the red frame spanning E2–H2 and E4–H4 that changed more notably. It also shouldn't have been a major factor, being directly mounted on 4 columns, and not anywhere near the initial collapse. E2 and E4 survived to the end, defiantly poking out of the top of the controlled demolition, as the building dropped slightly ahead of them. They changed it from two separate units to a combined unit, so overall weight should have been in the same ballpark.

Quote (Vance Wiley (Structural)10 Jul 21 18:43)

How many units were there? It looks like the last ones sold went for about $700K. What was the square foot each floor?

Here is some recent info
_ _ _ _ _ _ _Studios _ _ _ 1 Bedrooms _ _ _2 Bedrooms _ _ _3 Bedrooms _ _ 4+ Bedrooms
Total: 342 _ _ _0 _ _ _ _ _ _ _ 54 _ _ _ _ _ _ _219 _ _ _ _ _ _ 66 _ _ _ _ _ _ _3

SF Charlie
Eng-Tips.com Forum Policies

Quote (Thermopile)

Spartan 5, you have a concrete and masonry parapet wall surrounding roof, that is around 42" high to deflect wind from blowing outdoor units around

In a Category Anything storm making landfall right at the building?

Is that your guess or are you telling me that the code makes no requirements for the secure mounting of mechanical equipment on the roof in high-velocity hurricane zones because a 3-1/2’ knee wall will keep them from blowing around in 100+ MPH sustained winds? You can’t see it but I’m making my skeptical face. If that’s the case, it will be the most shocking thing I’ve learned today.

I find it really hard to believe that Cassondra in 412 saw bits of the roof falling down and then called up her husband to say the pool deck was collapsing and she thought it was a sinkhole. I kind of bet the damage to the pool deck wasn't nearly as wide spread when she made the call, or there's no way she wouldn't have just run for the exits. I think more than anything, the lack of survivors really shows how much the building stayed mostly together until those last seconds.

As I posted earlier, I'm an HVAC/ Energy conservation engineer. These units are required to be bolted down. I've installed several units myself, even in the early 1980s. Every heat pump/air conditioner I've ever seen has factory holes at the bottom of the units for mounting. Some are easily accessible and the instructions that come with the units say to mount them. The ones I installed were attached to steel concrete anchors embedded at least 3" into concrete slabs. I can't say if an installer skipped this step but an inspector should check.I've installed York, Carrier, Trane, and Mitsubishi and all had sturdy mounting holes and tabs at the AC unit's base.

There are factory holes at the bottom of the units often offset so you can get to them and bolt them down without throwing a strap over the top of the AC unit. Even in the early 80s.

All, even composite have to be designed for mounting even at your house. And on the tall Mitsubishi I put in the unit had heavy duty tabs with a hole in it that extended 3" from unit for easy installation. No regulatory bdy would accept loose units not bolted down. Not inland either due to wind or tornados.

Quote (Thermopile (Aerospace))

I never said anything about what the code says.

I know my unit residential at ground level is not tied down in any fashion. That's beside the point. What are the odds that one unit out of how many on that roof had a degraded or corroded attachment that broke loose considering the claims of neglect elsewhere?? I get your point though. Also it was somehow inferred that the sheer weight of the units played a roll (not by you). I think the weight distribution in the unit was only pointed out to state how easily these would roll or topple if they broke loose. The fact of where it may have ended up is symptomatic or some prior event taking place and nothing more. I think.

If you have a residential unit not tied down you had a jack leg installer. The three I've had at my house were all fastened to the 4 x 4 ft concrete slab first put in for that purpose. Codes if you have any specify it. Guess I have to dowload a Rheem manual. Simply crazy to think you don't bolt it down.

There's a new interview from the woman in 506: https://www.youtube.com/watch?v=5Tg_Z0sSNg4

Sounds like she heard a thunder noise and saw dust before the building collapsed.. or perhaps that was just the first part of the collapse.

Quote (zebraso)

What are the odds that one unit out of how many on that roof had a degraded or corroded attachment that broke loose considering the claims of neglect elsewhere??

Slim? Considering the building just had a comprehensive 40-year inspection by a licensed SE/SI.

Even in the fringe theory outlined above the inset picture shows that the units were mounted to a rigid frame of some sort above the roof surface.

The roof first collapse theories don't really line up with the following:
1) eyewitness accounts that the pool deck collapsed first, they called it a "sinkhole"
2) the punch through failure of the column/pool deck connections at the the columns. If the building fell first on the pool deck, you'd expect to see shear failure at the impact area instead of widespread "settlement" of the entire deck and several columns that demonstrated punch through.
3) the collapse video shows the face of the building collapsing as one piece, suggesting a failure at the foundation. With a top down failure at the roof, you would see pancaking of the top cascading down to the bottom.

No telling what happened at Champlain. Due to increases in efficiency in new units and becase R22 refrigerent used even 20 years ago in new unitw, these units have probably been replaced at least twice since the early 80s. Maybe the installer didn't bolt down but should have in a hurricane prone area. Sure its req'd in Miami. I had a tall Carrier installed at my house that didn't have offset tabs that reqd taking the grill off the top to bolt it down and using a long drill bit to put new holes in the slab to install new anchors. Still had factory supplied holes for mounting. Didn't mean to go off on a tangent.

Quote (prompted by the Champlain collapse they just closed half the Miami/Dade courthouse for immediate structural repairs.)

Amazing how fast the authorities act when it affects their livlihood...

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

-Dik

I sure don't know how things work in Miami or in condo;'s, but I would think each unit's HVAC system is the responsibility of each Condo owner, since it is not part of the common property, with the exception of the common area unit. That being said, each unit owner is hiring the jack leg to do their replacement units, I would think

Quote (julutamu)

you had a jack leg installer

Well, the previous owners had the jack leg installer- but mine was not bolted down.

Wind or not- they should be bolted down simply so the lineset is not a main component of the provider of force reacting against the start up torque of the fan motor.

I guess you all have never seen contractors in the Miami area glue/epoxy cut off bolt heads onto things.
Calling the quality of Miami area installers jack legs is an insult to jack legs.

You know the ol' saying. Tighten her until she starts to loosen, then back it off a quarter.

There may be more reaction torque from a vertically aligned compressor. It is often many times the HP of the fan.

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

Quote (MarkBoB2 (Electrical) 10 Jul 21 18:41)

Great work!

The following images compare the TikTok view to that of the Champlain North tower from Google Earth. It seems that the column between stalls 27 and 28 has been obliterated and perhaps the rebar from the column lays across the entrance aisle. The column at front of 28 (next in line in these images) is known to still be standing having punched through the slab and being visible in the post collapse imagery.

The missing column would be unique in not having punched through and this would be consistent with impact from falling debris. MarkBoB2's comparisons are compelling even if hard to believe.



In the following, I've scrunched the image width to somewhat account for the difference in perspective.

The unsecured residential cooling unit rolled through a parapet wall… free-fell 12 stories before slamming into the concrete slab below… and is still recognizable. I’m amazed by that too.

Quote (Thermopile (Aerospace))

The new inverter driven compressors have almost no torque steering of chassis

The starting torque requirements for traditional ac induction blower motors is low. You can start them with your little finger if the run capacitor goes bad. From there it's smooth even acceleration. Mine is not bolted down and it does not ever shudder slightly on start up. There is very little internally generated peak force being expressed to the frame. The fan motor torque could never ever move the base or threaten is security.

A note about the mystery cylindrical object in the tictoc video; I agree it looks like a garage ventilation fan. But the recent YouTube video with the lady walking through the garage in 2020 does not show any similar ventilation fans. The picture SFCharlie reposted is not from this garage. The paint on the columns is wrong.


I am not sure about the entire penthouse roof hinging as a solid slab. If the infamous roof anchors caused something to fail, I think it would just be the cantilevered roof over the balconies and the parapet wall.

That may well be the trigger that caused the mostly agreed upon initial failure of the pool deck. I find it very likely something atypical happened to the pool deck to initiate the failure. As it has been mentioned, once the deck failure began the rest was inevitable.

JR97

Rheem hold-down strap.

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

I was the one that posted the ventilation fan pic so I wanted to clarify - it was not a pic from this building. It was used as an example. I apologize for any confusion.

That said, the renovation plans DO show a “jet fan” in that approximate location. I could not find a detail showing what model fans they were, and we don’t know if they were installed or not.

I continue to think that some degree of early damage occurred on the western penthouse roof - these images is from the surveillance camera’s perspective, and includes the camera itself. The drop of this middle area is not well explained in the context of the lights still being on. Both theories need some work, and there isn’t much to prove or disprove.

It’s incorrect to say that it’s impossible because nobody reported falling objects. How many people were watching before the booms?

As for occupants on the upper floors or in x10/x11 above floor 7, we don’t know if there ere any that night. The lack of complaints doesn’t mean there wasn’t an event there.

Finally, a roof collapse could have occurred even seconds before the main collapse, and that would explain the missing parapet. Again, I don’t see how any of these theories can be ruled in or out at this time.

Js5180, We actually do know that people were on the 10th, 11th and even the 12th floor. This is a bit outdated now, but it shows who was upstairs - https://archive.is/QmPiY

I guess it's a bit more thrilling to think that you can see stuff from the roof on the garage door in the tiktok video even though it's really grainy, but it can easily be explained by stuff that's sitting on the pool deck that we know has collapsed there. If all of those shapes are items from the roof, where are all of the large planters, circular tables, etc from the pool deck. Also, I think you can see the column lying on the ground between 27 and 28 on the floor there, with the top facing towards the southwest and the bottom covered in rubble. It's more obvious in the original video than it is in the lightened photo though, because it's the only thing that's clearly painted white.

Sym P. le, That before garage photo is a bit off too.. the streetview pics from 2011 are a closer perspective and you can just barely see the column towards the top of the screen in that one. I believe they were posted around part 3 or 4 though, so I'm not going to post them again.

The round object in the tiktok video is not readily explained as an all-black table. It appears in the video as a cylinder, with light colored walls, and a concentric circular opening that’s darker.

Saying it is more likely to be a table ignores the obvious - it just doesn’t look like a table.

As for the green, I think the green in the tiktok is way too artificial and man made to be plants. The fact that an enhanced picture was able to bring it out so easily suggests it is very consistently colored.

If an AC unit falls off a 12th floor roof and hits the ground, that's what, 4,000lbs of force give or take on impact? If that will make the pool deck collapse, then the building was absolutely doomed come morning time when everyone was leaving for work.


With how much it's been raining down here recently, and how poor the drainage and waterproofing in that area was, I don't find it unlikely at all that there could have easily been 3" of water sitting just under the surface of the pavers. Even as first responders were first getting there, water was puddled up in spots that had yet to spray with hoses and had not had water mains leak on.

How much water weight could potentially be on that slab? Seems likely far more weight than that of any falling AC unit.

Js5180, That photo has been lightened.. check out the original video - https://www.tiktok.com/@adrianitacastillero/video/... To me if very obviously looks like a shiny black table, it even changes colors as she zooms in that hints that it's glossy, flat and reflecting some light from the garage. Also, glossy black tables can look grey too in photos btw.. and how the glossiness shows up, especially at low resolutions, can sometimes seem like there's an inner circle. The green bushes in their planters were also quite large, and that photo is lightened which can make colors look more consistent than they actually are. I guess I'd find the roof theory more believable if we could see pool deck items as well as roof items, but it seems to be one or the other.

I attempted to overlay the parking spot plan on the framing plan to help with cross referencing. It's not perfect but it's as close as I could get it.

https://files.engineering.com/getfile.aspx?folder=...

Another overlay with the planters and test probes superimposed on the framing plan and parking lot plan.

https://files.engineering.com/getfile.aspx?folder=...

• https://files.engineering.com/getfile.aspx?folder=17c4e297-9607-4223-9680-a

@Demented - good point about the water weight. Do we know if there was a drainage system installed prior to the collapse? It looked like white pvc drain pipe was hanging below the plaza slab in the parking garage tour video. But that may have been for something else.

The planter soil may have been quite saturated as well.

The "impact by falling roof stuff" theory is certainly sensational in comparison to the more pedestrian "highly-deteriorated, minimally-redundant plaza slab system gives up ghost" theory.

For the roof-based theory, it sure seems like there needed to be a chain reaction of components experiencing there own acute, sequential worst case scenarios.

For the deteriorated plaza theory, all it really needed was father time and breakdown of inherently impermanent / imperfect systems.

Something cut this building's legs out from under it. I personally lean towards the plaza deterioration theory. At the same time, the falling roof debris theory isn't an impossibility.

Just a few observations of this particular area.

Reposting coz I mistakenly posted this on the old thread:

Quote (CE3527 (Civil/Environmental)10 Jul 21 15:05 Question remains why the F/A didn't activate when sprinkler lines broke in the garage. Speculation here, that these devices either weren't working or were deactivated to prevent false alarms))

Another possibility: the water in the video wasn’t coming from the sprinkler lines. Didn’t the planters have some sort of automatic watering system? Perhaps the pipe that broke was related to that?

(I’m not necessarily endorsing this theory; just putting it out there as another possibility)


“NOOK-yoo-ler. It’s pronounced NOOK-yoo-ler.”

Quote (bones206)

@Demented - good point about the water weight. Do we know if there was a drainage system installed prior to the collapse? It looked like white pvc drain pipe was hanging below the plaza slab in the parking garage tour video. But that may have been for something else.

The planter soil may have been quite saturated as well.

Ah, the planters. There's a chance those were full of water too, and I mean FULL.

3-4 years ago a contractor from the Miami area hired me to make some planters for a well known hotel down there. Wound up not doing the job, but his plans called for 2ftx2ftx10ft planters with no drainage, and mounting tabs so he could just lag bolt it down to the concrete where they wanted it internally.

I don't think a drainage system was installed prior to, or work had even begun on fixing the issue with the drainage. I'm an hour north of Surfside, and up here, from the 21st to the early hours of the 24th, we received 2.44" of rain, and it's been on the drier side here compared to more south. It's been mostly cloudy too, and water has just been sitting here in puddles. Especially areas where there's a lack of drainage, 3-8" of water easily pools up where allowed. Sloped drainage areas with clogged drains, especially around landscaping day or windy days when lawn debris is everywhere, are all too common.

Even though there is a pipe hanging, that may have absolutely nothing to do with the fire system. (Plus, if the penthouse collapsed first, where were those fire system alerts?)
The slab could have fully cracked through, or even epoxy injection repairs could have failed, allowing the sitting water on top to start to flow through cracks, which could explain what we are seeing. To me it looks like no more than a small amount of water being poured or drained, similar to the amount you'd see coming from a gutter/drain system, not a pressurized system for fire suppression. I've seen those break first hand, and you actually get gushing, not the slow, 80 year old man prostate dribble coming from the upper deck in the tiktok video.

Precision guess work based on information provided by those of questionable knowledge
Aerospace/Industrial/Medical/Structural
SoFla

Quote (Demented (Industrial) 11 Jul 21 00:49)

You are building the argument. Tons of water plus junk from the roof may be the difference.

If 1" on 1 acre is 113 tons, then quite literally tons of water.

Precision guess work based on information provided by those of questionable knowledge
Aerospace/Industrial/Medical/Structural
SoFla

bones206 - I feel pretty strongly that the deck collapsed first. It's hard to know the exact origin with the available evidence. What you suggest is a strong candidate. The other area of interest to me is the at grade parking area south of the lobby and west of the pool deck. This area was also in poor condition based on the reporting and videos. It too had planters but unlike the pool deck, there is no evidence this area ever had waterproofing in its 40 year history, then add in the live load of cars backing in and out for 40 years.

I also feel pretty strongly that failure at the area you point out led to the eventual collapse of the building. Start on the basis that the deck collapsed first, and then ask why some parts of the deck simply punched through supporting columns or sheared away from the structure, yet this particular portion of the building collapsed? Then ask, what is different about this area? The answer to that is that this area had a stronger connection to the building than any other area of the pool deck because of the beams supporting the step down terrace. And therefore, the most likely area of the building structure to be impacted by a failing pool deck.

There are some question on Reddit if Cassondra Stratton was in unit 412. Since the body of Miguel Pazos, the owner of 412, was recovered in the rubble. Apparently, the unit Cassondra has taken selfies from recently is a x10 unit, possibly 410, it's possible she moved units.

This would, to some degree, change her view from the balcony.

https://www.reddit.com/r/CatastrophicFailure/comme...

BKNJ

Let me explore this from a different angle.

Let’s look at the column M10 stack - this is next in the row, west of “27”. I’m pretty sure most of us agree this column was compromised and played a major role in the collapse (even if not the trigger).

The roof extends a good bit past M10 - I’m estimating 8 feet. At the edge is a CMU parapet.

If M10 has sunk and M9 has not, then the roof will slant outward. The outer face of the parapet is now inches over the edge of the building.

At this point, doesn’t the parapet now become the weakest link? The rest of the collapse portion, when it falls, is tied together. The parapet is now a few degrees off vertical. It is held on only by a few bars. We saw in the controlled demolition - a section of parapet actually separates from the roof in free fall.

Each foot of the parapet weighs about 288 lbs. Each foot of cantilevered roof, on the south wall, weighs about 900 lbs. And that’s a 6” waterlogged slab which appears to be exactly where some level of roof work was being done. It would take very little “sink” in columns K/L/M to cause that parapet to lean or that cantilevered slab to bounce like a diving board.

The parapet, in my estimation, would almost be expected to break off, even with the slightest drop in one of those column stacks.

Quote (julootamu)

If you have a residential unit not tied down you had a jack leg installer. The three I've had at my house were all fastened to the 4 x 4 ft concrete slab first put in for that purpose. Codes if you have any specify it. Guess I have to dowload a Rheem manual. Simply crazy to think you don't bolt it down.

There must be a lot of Jack leg installers around then because I've owned 4 homes in 3 states and none of them have had their outer units bolted down. Several of these homes had multiple units and there were at least 3 different brands of units involved.

Isn't is also possible the foundation is the problem, and that caused the column to collapse onto it's side from below? It'd make sense then why the inspector doesn't seem to see this problem before it developed. Also, that crane falling across the piles back in the 1980s could have done some minor damage to it, and it looks like it could have fallen around those columns that collapsed.

Couldn't it also just be caused by a sinkhole under the foundation? If the concrete was leaking water down to the garage from the pool deck too, it seems likely that the foundation was doing the same.. perhaps that caused some damage? It was above limestone. It seems very odd to me that this column collapsed onto it's side, but the column next to it puncture sheered and there's nothing that shows that the pool deck was pulling the collapsed column towards the southwest. It looks like the pool deck just fell straight down.

I found this map which seems to say that it's possible.


Some articles also say that Cassondra was in 410 and not 412 - https://www.usatoday.com/in-depth/graphics/2021/06... (Cached version that doesn't require an account: https://webcache.googleusercontent.com/search?q=ca...)

A sinkhole opening up in a formal tidal pool? Nah, no way.

Precision guess work based on information provided by those of questionable knowledge
Aerospace/Industrial/Medical/Structural
SoFla

So, the pool deck. If the pool deck collapsing is the initiating event, then every single column supporting the pool deck, has to be a clean punching shear. Right? We have the TikTok video, which people claim there is a column that looks tipped over right? Gone, vanished. Where is this column? Would I be correct in assuming that the punching shear is easier to occur then a disappearing column? I mean, those columns look real tough. Like, say what you will about the connecting rebar on the pool deck to the columns, but those columns survived an entire pool deck slamming down on them from above.

So, the pool deck gets super old, it's had it, it collapses to the ground. Somehow causes the entire building to collapse. Right, sure, so then we should find every column still in it's rightful place punching through the pool deck.

There is the opinion that the roof collapsed over the side and slammed into the pool deck. Sure, that's possible, I don't think you can argue either for or against this. Needs more evidence. But, how does the roof crashing into the pool deck, somehow magically destroy a column? It just magically slammed into the exact position on the ground where the column was and Thor's hammered the crap out of it from above?

This isn't obvious, neither of these two could possibly be the initiating event, because we still have a missing column, where is that column? Also, the pool deck above the missing column looks intact right? So, it didn't punch through and then disappear right? It wasn't obliterated by the building falling on top of it. So, what happened to it?

Well, I think this matches with a side collision from a vehicle. You have a vehicle slam into that thing at full speed, and you've got enough of an impact to knock that thing out from under the pool deck. The connection to the pool deck is not much. So, if I am right, then your going to have a dead motorist crushed under the pool deck, inside their vehicle, next to a collapsed column.

But, how exactly does this happen? Well, you think about it, car is coming down a ramp, maybe the driver is tired, being it's late at night, and a foot taps the wrong pedal, and before you know it, it's right through the column. Why is this a difficult concept? It happened to me, old lady next door, she had a V6 she used to park in the backyard under a shady tree. Her meds are making her tired, and she gets in her car, winds the window down, and before she knows it, she's made the car fly 10 meters at speed through a fence and into the next door neighbours garage.

In 10 meters this woman dropping the foot to the floor on grass in her backyard, had managed to cause structural damage to a double bricked garage.

That guys story of "power is out", "left my car down in the garage", "left on my scooter". Something about this seems a bit BS to me. Like, you imagine if the person who did slam into the column, had managed to get out of the area before the collapse, you think they'd want to be honest about the situation, like, yeah, I just killed 150 people by driving drunk / tired into a column.

And, honestly, I've known plenty of people to slam into building columns. My uncle did it in an old BMW once. Wrecked the rear of his car big time. The column stayed in place, due to it supporting a 5 story building. In Australia, our columns are super thick, and honestly, I think these columns were probably very thick as well. Just, I don't think they were rebarred well at the top and maybe at the bottom.

The columns might be super strong, so you'll probably find them intact. I think of all the issues this building had, those columns were not one of them. And you tend to over engineer columns if they are going to be supporting the weight of a building. The columns under the pool deck, looked to be a very similar strength to those under the building. With one exception. The columns under the surviving structure were stronger.

You think maybe when they did the columns under the pool deck, they were thinking of the future? Like, in the future you might want to expand the building above the pool deck? It wouldn't surprise me. Like that pool deck is taking up valuable real estate.

On another note, people say the building is in bad shape, but it doesn't actually look that bad, like you can clearly see a bit of money going into fixing the cosmetic appearance of the building. The boards priorities with repairs seems to be entirely based on increasing condo value. If I owned a condo in an old building and was on the board, I'd probably be doing the same thing, getting the hell out of there.

Quote (spartan5)

You reference a narrative about this roof collapse being built by warrenslo and dold… but I don’t recall seeing anything being said by dold to that effect. In fact, they had this to say:

Thanks for backing me up on that. I've always been an advocate of the pool deck collapse mechanism (ref threads 1 and 2), and have found the roof anchor discussion quite tedious.

Id like to comment on the redundancy of modern PT construction. Current codes require a minimum number of tendons (cables/strands/etc) to pass through the core of the column in each direction. This provides redundancy in the event of a punching shear failure as we see in this collapse. The intent being to prevent the failed slab from dropping its full weight onto the slab below - with obvious consequences.

However, even if Champlain towers south had such a system, it isn't really clear if that would preclude a collapse of this nature. To me (and as presented in the youtube video+translation) it seems that the collapse initiated at the pool deck slab somewhere, and caused some sort of perturbation in the columns supporting the south side of the north wing (can't remember the gridline at the moment) ultimately leading to the column buckling. Most likely, in my opinion, caused by loss of support at pool deck level via pool deck collapse.

I feel like at that point, no amount of redundancy can stop the momentum of 12 stories of concrete frame once it starts moving.

The columns and particularly the slab to column joints are just going to get rubble-ized. Consider the photos that show apparent voids at the floor levels along the height of the column stacks. I have no calculations to back it up, but the slab mix was 3-4 ksi and the lower column mixes were 6-7 ksi if I remember correctly. Really just food for thought, but under impact loading, I would expect more of a crushing failure as opposed to an instability/buckling failure. Which appears to be reflected in many photos. A secondary effect of this (also mentioned in the translated YouTube video) is the rotation of the entire collapsing structure about the vertical axis - read: P-Delta).


And about this RTU anchoring business. Current Florida building code amends and SPECIFICALLY addresses the design wind loads on roof top equipment. I think its factor about a 2.5 in Florida vs a factor of 1.9 for the vanilla IBC (uplift coefficient). You're looking at pressures well in excess of 100-150psf for RTUs in that exposure and height AGL. Nobody would consider shielding from a 3.5ft tall parapet thats 10ft away (...probably). I guess none of that matters if it was installed by some unpermitted jack leg.

Even if it was just loose, i have a really hard time imagining a 250lb residential unit just...falling over...then causing a global collapse of a building.

AutisticBez,

One problem with this theory, is that if a car hit missing column, and completely displaced it, the car should probably still be there. And it’s not. It’s the billiard ball or swinging cradle thing.

I think it’s pretty clear that a pool deck collapse weakened the rest of the structure, especially around units x10/x11.

The question is more about what caused an already weak pool deck to collapse. Did it collapse on its own, or was it hit?

AutisticBez , I think the column is right here, but it's easier to see in the original tiktok video since it's the only object that looks white and this photo has been lightened. I'm less sure about that horizontal column than I was when I made this graphic though.. this was posted in part 4 of this thread too.


If that is a column, the bottom seems to line up well with where a column should be, but it's too covered in rubble to see it. I think if a car had hit it we would see a car here, underneath it or the rubble. But it would have had to hit it with such force.. I don't think a car would be capable of it. And yea, a few stories from the building sound odd.. but that's also how the truth sounds sometimes and they all seem plausible. That guy with the scooter also wasn't the last person in the garage btw, two actors from Argentine were and they had just gotten into the elevator when it went down. They then left the country in a hurry.. but that's also just how rich people act.

Quote (SFCharlie (Computer))

Thank you for the building data, Charlie.

Quote (AutisticBez)

Well, I think this matches with a side collision from a vehicle. You have a vehicle slam into that thing at full speed, and you've got enough of an impact to knock that thing out from under the pool deck. The connection to the pool deck is not much. So, if I am right, then your going to have a dead motorist crushed under the pool deck, inside their vehicle, next to a collapsed column.

But, how exactly does this happen? Well, you think about it, car is coming down a ramp, maybe the driver is tired, being it's late at night, and a foot taps the wrong pedal, and before you know it, it's right through the column. Why is this a difficult concept? It happened to me, old lady next door, she had a V6 she used to park in the backyard under a shady tree. Her meds are making her tired, and she gets in her car, winds the window down, and before she knows it, she's made the car fly 10 meters at speed through a fence and into the next door neighbors garage.

If the columns were even close to their design strength in automobile running into them would not knock them down or even severely damage them. Going through a fence and our neighbors garage like you described is completely different, those are much less solid structures.

JBourne,

Column M11 should be about where the word “both” in your graphic appears.

I pointed to the wrong beam in my last post. I went back and checked the video again and it was actually the next column line to the east, which was closer to the core drill. Also saw what looked to be a planter drain.



Note the Column at M11.1 is quite smaller in cross section, possibly 12" x 16" - much more susceptible to a vehicular impact. But if that's what happened, the only way we will ever find out is through surveillance video or a confession.

The thing that's nagging in my mind is the column on the left (M10) is supporting the building and the column on the right (M11.1) is only supporting plaza slab. But since they are connection by a beam, if the column on the right (M11.1) collapsed for some reason, the falling slab would cause the beam to rotate clockwise and put a huge bending moment on the left column (M10). That's a plausible trigger for the subsequent building collapse.

Quote (Vance Wiley (Structural)10 Jul 21 18:43)

How many units were there? It looks like the last ones sold went for about $700K. What was the square foot each floor?

Here is some recent info, please see attached file:
It shows:
    the average price for units w/# of bedrooms over the past 24 months
    the average price for units w/# of bedrooms times the # of units that size
and
    the Total of the average price times # units for all units

SF Charlie
Eng-Tips.com Forum Policies

• https://files.engineering.com/getfile.aspx?folder=8bb117f4-94a5-474d-a9f1-6

Js5180, I agree with you? Although, it wouldn't be quite at that word and closer to the 'th' in 'both.' If we're looking at the top of that column in that pic, it's easy to see where the bottom would be if it weren't covered in rubble. It looks like it's still all in one piece.

bones206, Interesting, I hadn't noticed that pipe but it does seem like that could be right under the planters in front of 111.

Okay, the columns are strong true? But what if whatever is connecting them isn't? What if it's possible to dislodge a column simply because the connection with the pool deck and the foundation, isn't strong?

The water coming in, would rust and destroy rebar, but it probably wouldn't damage the columns so much as the connection points? Those connection points are super weak. Concrete sheared off the columns easily. But the columns are still there?

If the basement had a lot of flooding, perhaps the rebar in the foundation connection to the columns is even worse? The water has to go somewhere right? So, a vehicle knocking down a column is impossible? Not even flying down a ramp at full speed? Can we myth bust this? Anyone got an old car and an abandoned parking garage to prove this?

AutisticBez

What production model car is going to gather enough energy to dislodge that column with at most, 85ft of run-up space on slick concrete from a dead stop? The garage entrance gate was closed too, and those things don't just slam shut. No car took out that column, unless both theories are correct, and a car fell off the penthouse roof onto the pool deck.

Anyone else notice that M11.1 is super thin right at the top? There is a beam between M10 and M11.1, but the beam is sitting on a real skinny bit of M11.1 column right?

Quote (bones206)

Per the drainage plans, that would indeed be where a 2" planter box drain is called out.

Precision guess work based on information provided by those of questionable knowledge
Aerospace/Industrial/Medical/Structural
SoFla

I think a car can do a lot of damage in a short space of distance. Most people don't flat pedal cars. I think in my entire life I've never put the pedal all the way down. Most people don't. An old grandma in a super overpowered 6 cylinder 4 litre plus car, she's probably never flat footed that vehicle. But you know, if you've got a variable cam timing engine, and you flat foot that shit, and it's like warp speed. By the time you realise what you did, you've magically displaced a lot of distance in a short period of time. Most of us regular car drivers, the rpm's sit between 1000 and 2000 most the time. Transmissions tend to keep it low to conserve petrol. But, giving it a 3 or a 4 on the onramp to the freeway. Flat footing that pedal is an entire other story. Come on, even my shitty sedan could wreck a building column. It's nowhere to be seen, you find me a single photo with an intact M11.1

That’s just a trick of the light. The column isn’t skinnier at the top.

Column M11.1 failure doesn’t have to be the initiating event. That beam could have simply failed at mid span and it would have had the same effect of applying a bending moment on column M10.

Quote (Can we myth bust this? Anyone got an old car and an abandoned parking garage to prove this?)

Myth busted. Tree still standing after highway speed impact with mini van.

Dude, the tree has a massive root system buried in the ground. And the car has a crumble zone that is weak as all hell. Can you see how the impact stops at the end of that crumble zone? Tree's are much stronger then columns surely?

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.

Does anyone see the black stuff In the middle of the rubble. I thought it was a contiguous object at first but then I think I realized that some of it is interspersed with shadows due to the lighting orientation amidst rubble, and it just looks like a continuous piece of something. And then for some unknown reason I thought of roof paper rolls. And then I looked at it a bit more. Thing that bothers me is that I did not look at it with the idea of finding roof paper rolls. I was not looking for them.

From AutisticBez: "Like, say what you will about the connecting rebar on the pool deck to the columns, but those columns survived an entire pool deck slamming down on them from above."

No. It was not "above". It was at the same height. There was not "slamming down on them from above" by the pool deck.

If you disagree, please state the height of the pool deck above the columns.


spsalso

zebraso,

I am missing your point. I think it's been said there was roofing paper rolls on the roof. Everything fell down, with the roof pieces on the top. I would expect the rolls to be there, on or near the top of the pile.

Please explain why you are surprised.


spsalso

https://res.cloudinary.com/engineering-com/image/u...

Now that your mention it, I think I see the rolls of roofing paper in the middle of rubble.

It appears the NIST is doing a stealth investigation. It's over 10 days, and no news conference.

Are there cameras recording the debris removal? Where is it being taken? Is it being keyed in any way to the location where it was found? Are the NIST investigators on site? What are they doing when they are on site?

Did NIST approve of the standing building's destruction? Did NIST collect evidence for their investigation prior to the destruction? How did they do this?

What is the name of the lead investigator? What are the names of the other members of the team (approximately 6, I believe).

Why has it taken over 10 days to hear from these investigators?


spsalso

Quote (Awestruc)

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.

1994 Northridge earthquake - PT integrity tendons support severely damaged slab:

JBourne, no, it wouldn't be at the th in "both." If that was the case, the columns would be equidistant in the photo. But they are equidistant in real life, which means in the photo, you have to account for perspective. Each subsequent column in the tiktok video is about 2/3 the distance from the lsat, from the photo's perspective. That moves the M11.1 (which I was calling M11) aa little to the left in the tiktok, to about the "BOT" in the "BOTH" but definitely not at "OTH."

The columns survived whilst the pool deck is a shrivelled up mess. Figure of speech. The columns are strong, the pool deck was weak. The rebar in the pool deck, also weak. They added to the dead load of the pool deck by paving over it. But the columns under the pool deck look strong. Too strong. Like, why would you need such thick columns under a pool deck?

I guess I don't believe falling debris from the roof is capable of making an entire column disappear. This to me is something else. Could a car cause a column to dislodge from the top and bottom?

Quote (spsalso (Electrical))

Please explain why you are surprised.

Sorry about that. I wasn't trying to be elusive. After I posted it I realized I left out the context. I meant to post as an ongoing description of what is in the tic tic capture that has more recently been under review. I mean to describe what occurred to me as it appears in that enhanced capture. So that in effect this would describe roof paper rolls in the basement before the main structure collapsed. I meant to look at it as objectively as I could. But what I think I see is roof paper rolls and then as mentioned before in the thread, not far away in the basement is what appears to be a material that is the color of the tarp that was used to cover said rolls. If anyone mentioned the appearance of the actual rolls in the basement before I missed it.

Thermopile,

Yes, I see that too. I am sure our NIST investigators will, uh, investigate. And perhaps confirm it's rolled roofing.

They are PROFESSIONALS, damn it!


spsalso

Also, if anything in the tiktok could arguably be a CMU, well, then we have a roof-first event...

The left side of image looks like 3 rolls of tar paper all lined up, with slight angle changes between rolls

zebrso,

I see the problem. You said "in the middle of the debris". Debris to me is the big pile at the former building site. You are talking about some debris in the parking area, down the ramp. I think.

Yeah, that surely could be roofing paper. Or something else.

Rest assured, the NIST is on the case!

Then that could mean broken column is leaning onto Square planter from above

Maybe that'd be a good experiment too, toss a bag of roofing rolls on the ground from a few stories up and see if you can get them all to land in one spot. Looked like some sort of metal bar to me.. maybe a deck umbrella? I'm not sure anything on the floor of that tiktok video can be positively identified, except for maybe the column and planter since we know exactly where they'd be. Is this all we're going to discuss now? I'm not sure I see the point when the video is at such low resolution.

It's interesting too that it sounds like Cassondra was in 410 and she only described it as a sinkhole under the pool deck, instead of the upstairs parking area as well. It really makes you wonder how extensive it was when she made that call.

Js5180, I think you're underestimating how far apart the lengths would descend from this perspective.. either way, it can easily still be that white object at the bottom of the pile of rubble there.

Thermopile, How would the column end up on top of the planter though? It's also too far back.

Thermopile:

"The left side of image looks like 3 rolls of tar paper all lined up, with slight angle changes between rolls"

That is some quality roofing paper, to remain (semi-)usable after a fall like that. I should get the manufacturer's name.


spsalso

I was figuring planter rolled on way down, and column did not fail immediately?

Like this, for example:

On the left is a completely destroyed column supporting a building. As a result of this impact, the building had to be shored up, and a new column constructed to replace it.

Sohel, K.M.A, Al-Jabri, K & Al Abri, A.H.S, 2020. Behavior and design of reinforced concrete building columns subjected to low-velocity car impact. Structures (Oxford), 26, pp.601–616.

"The columns that are located in car parking garages or adjacent to roadways are highly vulnerable to out-of-plane loads imposed by the moving vehicles. The column that is subjected to impact force imposed by a vehicle traveling at high speed may be damaged severely and lose its design strength, which can lead to failure of the column"

"Consequently, this can cause the column to fail in taking the applied loads on it. Therefore, the loads have then shifted to the adjacent columns, where those columns may not be designed to support such additional loads. In the worst case, the failure of the column can lead to a progressive collapse of the affected building."

Can't even make this stuff up.

"At an impact velocity of 40 km/h, Column C300 suffered moderate damage at the crash point as well as at the base of the column (Fig. 9a). However, at an impact velocity of 50 km/h, the column C300 failed by shear near the base of the column (Fig. 9b)."

"Column C400 failed in shear at a car impact velocity of 80 km/h,"

C300 300 × 300 2.6% 3101.8 27.26 4
C400 400 × 400 2.6% 5558.2 25.99 8
C500 500 × 500 2.6% 8685.8 26.54 12
C600 600 × 600 2.6% 12506.0 27.58 16

How thick was M11.1?

It is possible, you can't rule it out. If the connecting rebar at the top and bottom of the column M11.1 was weak as the rest of the pool deck, well, why not? It's hardly a worse possibility then the roof anchors nonsense that has legitimately no eyewitness statements. If there was a column impact anywhere in the garage, then M11.1 seems like the most likely target.

Quote (Demented (Industrial)11 Jul 21 03:29)

What production model car is ...

My dads Royal Monaco S/W with a 400
... provided the engine mounts are good.

Jbourne,

If the columns are equally spaced on the plans, then the spacing in a perspective photo would be an equal ratio, not an equal spacing.

For example, in the tiktok, if the distance between the right edge of the shear wall, the end of the ramp pillar, and the "27" pillar is the same, then you can take the pixel counts and extrapolate the next pillar location.

Let's say on the plan, the pillars are 20 ft/20 ft/20 ft/20 ft, and in the perspective, the visible ones are 200-160-128 pixels between them. The next pillar will be 102.4 pixels beyond. That same math would put the M11.1 column left of where you're envisioning:

Js5180, I sae now, you are saying that object could be CMU in middle of your yellow oval. And yes that could be

Ok I see the perspective means the column would have been in front of planter, but planter is still in same area, which is logical. Just on other side of column perhaps. And some of what we are seeing could be parts of failed beam between 27 and 28 or slab.

Thermopile - I'm saying that if you think there's any possibility that the yellow oval is part of a CMU wall, then you have to consider the "fallen roof object" theory, because there are no local sources of cinder blocks at that area. Just like if you see roofing rolls, you are seeing fallen debris from the roof.

Js5180, I definitely see what looks like roll roofing and cinder block, now that it was pointed out, and the image was enhanced.

So yes, roof first is still a viable theory

Quote (Thermopile (Aerospace)11 Jul 21 05:16)

Rolls of roofing paper?!?! Srsly, the plot thickens!

CMU's??? Whoa!!!

I have an idea, but I need some time to develop it.

As far as the security camera that caught collapse, I am not sure all systems have the look back feature? It was also at night too. My security cameras do have look back feature, and they are triggered by sound as well as movement. So a sound trigger like the penthouse roof falling could have been what 'woke' camera up?

I drew out the columns too.. perhaps this will illustrate what I was trying to say better. Sort of interesting, but this sort of makes it look like you can only see the bottom of pillar 28, but there's an object in front of it, and the column on top of the planter doesn't seem like it's necessarily part of the same column if that's the case. It's sort of strange too, since there don't seem to be any horizontal columns in that area in the 2020 tour video. Maybe it's part of the pool deck slab?


Anyways, if you take that column and place it on it's side, you can see it lines up pretty well with that white area.


I get those drawings aren't perfect too, but I'm not an artist and they look roughly correct. I think when you look at the negative recoloring of the photo though, that's when it becomes very obvious that there's just one white object on the ground. Not sure what else it could be really if it's not the missing column.


Also, couldn't those bars on the floor just be sprinkler pipes? We know they probably fell down around there too, and there were two of them.

If anyone has imagery of the work or documents pointing to activity on this roof portion at the time of collapse please reup it. Thanks.

Another thing that cinder block shaped object could be are those smaller white planters they had on their pool deck. You can only see them in the most recent photos, but they seem roughly that size. It's hard to say where they were exactly though, since it seems like they moved them around a bit.

Although.. the part I don't get at all, is if that white object on the ground is the column.. the direction it's pointing doesn't make a lot of sense. I tried to draw it out, but it's like the bottom of it is gone.. and the location of it is too far to the right. It's also not quite angled towards where the column was. I don't get how this wasn't a bomb really.. nothing else seems to fit with how this looks.


Also, it seems like you can see the rebar and metal sticking up in the spot where that column used to be once you draw it out more in 3D.

Maybe these white rocks are bits of the missing column? Again though, it seems crazy how far they are from where the column was.. this is about a car length and a half away.


Sym P. le, you can find them here - https://surfside.one/public-records-search/ All of the 2021 permits, the 2021 plan, and the preliminary review plans for the 40 year certification are probably worth looking at. The inspector was actually there around 14 hours before it collapsed too - https://www.palmbeachpost.com/story/news/2021/06/2...

Quote (jbourne8 (Computer))

Also, it seems like you can see the rebar and metal sticking up in the spot where that column used to be once you draw it out more in 3D.

Speaking of rebar, does this look like a J-hook or where a J hook was in a section of concrete?

Quote (Thermopile)

So a sound trigger like the penthouse roof falling could have been what 'woke' camera up?

Remember, it’s been established that the progressive deck collapse preceded the total collapse by at least a few minutes.

Y’all staring way too hard at that grainy image. You might could begin to see Stikini creeping around behind the columns if you squint just right.

New video of the recovery: Link

Behind a paywall but you can watch it in Incognito mode

Several closeups from various angles. Hard to make much out, but there could be clues in there.

Okay, so M11.1 is 12 inch by 16 inch by the plans. Guess which side is the 12 inch. The side facing the ramp. So, it's as wide as M10 from the direction of the ramp. But, it's thin. It's 12 inchs. Or 30cm. It would take a car a speed of 50km/h to destroy this column, in ideal conditions, meaning, if the rebar at the top and bottom of the column were decent and not rusted out.

I'm thinking the actual speed of a vehicle required to destroy this column is less then the 50km/h. Depending on the severity of the damage, much less. If the rebar is brittle as hell, as proven by the punching shears, then I don't think it's a stretch to suggest a car had something to do with this.

Now, if this column gets kicked out at the bottom, the car is probably under the rubble down the back.

Quote (AutisticBez)

It would take a car a speed of 50km/h to destroy this column, in ideal conditions, meaning, if the rebar at the top and bottom of the column were decent and not rusted out.

A drunk driver managing to do 30 mph into a column at 0100 is certainly a plausible scenario. So is an octogenarian stomping on the wrong pedal.

It might, however, not be necessary to "destroy" the column. All that's really needed is sufficient damage to initiate failure, which could even be delayed. Hit it hard enough to crack it and empty out the rebar cage a little over a few inches, and it will potentially be severely weakened. Or just push it an inch or two out of alignment and the load pushing down is now also pushing it sideways. There are more subtle scenarios than just suddenly destroying it.

I'm not yet seeing actual evidence to conclusively support either of those failure modes, just throwing that out there that it doesn't necessarily have to be a spectacular hit to set things in motion.

Similarly, if a heavy vehicle overloaded the surface parking deck, it could potentially crack it in the afternoon, but maybe the deck doesn't drop until the slab thermally contracts at 0100 (or some other slow failure mode, like each subsequent vehicle causes the crack to enlarge).

Quote (Spartan5)

Remember, it’s been established that the progressive deck collapse preceded the total collapse by at least a few minutes.

Y’all staring way too hard at that grainy image. You might could begin to see Stikini creeping around behind the columns if you squint just right.

Yep. Some people are so invested in the "roof-triggered event" theory that they are hanging their argument on imagery that is one step above a Rorschach ink blot.

Quote (jbourne8)

Maybe these white rocks are bits of the missing column? Again though, it seems crazy how far they are from where the column was.. this is about a car length and a half away.

They could possibly be from the top of M9.1, the result of severe damage to it when the pool deck and heavy stepped patio beam dropped. The east / right hand side of apartment 711 dropping slightly ahead of full collapse fits with that column failing in the final moments, then spreading out under the building from there.

Murph 9000,

The missing column from the Tiktok video is really a problem. Nobody has been able to explain it. All the columns under the pool deck, do a punching shear. You can find all of them but the one at the bottom of the ramp. Maybe it's obscured by debris? Maybe it was destroyed by the building collapse? It's just not present. Is it possible for falling debris from the roof to cause it to collapse on it's side? Then again, without the TikTok video, there wouldn't be vision of the missing column.

I know of one person who's backed a car into a column at 20km/h, it was a massive bump even at that low speed. I think people think these columns are super strong. They hold a pool deck up, how strong do they have to be? They might be very strong, but the connections to them aren't going to be that strong at all. Shear at the bottom is what I am thinking. Research itself points to this, with clear lab testing.

Quote (Seppe (Structural)11 Jul 21 11:18)

.
Frequency illusion, also known as the Baader–Meinhof phenomenon, is a cognitive bias in which, after noticing something for the first time, there is a tendency to notice it more often, leading someone to believe that it has a high frequency. (a form of selection bias)

Engineers understand this and they have a engineering method to evaluate problems systematically.
Other disasters also point us to this process taking many Months to Years... before they will have the likely answers to what was the cause & contributing factors for this.
Until then, this is a good forum to discuss many theories...

To all of those saying a car hit the column, are you saying it came down the entrance ramp? Did it come from the west underground side of the building?
In which position could the car have come from, with enough speed to obliterate that column and leave it laying towards the west in any way in the way everyone is claiming to see the column?
There's a good chance that column may still be partially, if not fully intact in that video, we just can't see it hidden behind planters, deck furniture, water draining, paver and concrete rubble, and dangling waterproofing membrane.

I'm still saying it looks like water found it's way down a weak point after collecting on top of the membrane. You don't even need a full section to fail, just enough to begin the destruction, that could from the top, match what was described as a sink hole opening up. A slow failure of debris getting swallowed up from the pool deck that spread to the collapse we saw. The TikTok video gives us at most 5 minutes of zoomed in compressed and grainy 380p. You guys are seeing far more detail than is actually there on shitty stills.

This was the section with massive water intrusion issues leading to water pooling on top of the membrane, correct? Not saying the column didn't collapse in anyway, but there's far more likely and explainable reasons as to why, considering the area, the deterioration, and the known issues. It's been very rainy down here. I mean, are we really trying to push aside known damage to an area from years earlier that has yet to be repaired?

Precision guess work based on information provided by those of questionable knowledge
Aerospace/Industrial/Medical/Structural
SoFla

waross posted a picture of a Rheem tie down strap for a split system AC unit. Looks almost home made. Here are pictures of hold downs on AC units installed at my house:

1. Picture of one of four bolts holding down a 3.5 ton Carrier (Factory provided holes but the top grill has to be removed to install). Replaced the Carrier w Mitsubishi.

2. Mitsubish Mr Slim heat pump with factory tabs (two on each side) to hold down AC unit. Prior to installing nuts on threaded rod embedded in concrete blocks that elevate the unit above the original slab. Blocks also anchored by rod into original slab.

I have a 2 ton and a 3 ton a/c on the concrete roof of my single family home in a hurricane zone. I have no doubt they would've blown over on the first windy day without being bolted down, but chances are the tubing and wiring would have kept them from going far. Plus they weigh maybe 100-150 lbs. Does anybody really think something of that weight could cause a collapse? Would a human body falling from the roof cause a collapse?

No I don't think a 100-200 lb AC unit falling off the roof in any way should have caused a collapse like what happened. Building supports should have been seperate ftom pool deck columns. Just like when I designed a deck behind a house. Made it free standing and not attached directly to the house.

Surprised that another camera didn't capture in higher resolution the collapse. Hope they find one to dispell roof debris idea easily.

I just posted due to one poster saying AC units are top heavy (they're not and fan motor typ. only weighing 20 lbs with heavier compressor at bottom of unit)) and other posters saying AC units aren't bolted down. Absolutely should be in huricane areas and AC manufacturers have provided mounting holes forever. All units I've been involved with have been bolted down and I'm inland. Commercial building codes require it and I'm sure residential codes in many areas. Just good practice at least to deter copper thieves.

Ok, if first pot hole was in patio slab minutes before building collapse, then the planter area is a prime suspect for punch shear failure of slab, leaving beams initially in place. Planter area outside 111 has not one but 3 beams tieing columns together under planters outside of building footprint. The 4th beam that closes this square area is at building perimeter. Thus more likely a bundle of rolls of tar impregnated heavy roll roofing felt/paper is able to take out slab before the 3 beams under planters. Roof first, patio slab pot hole second, then planter beams next, and so on.

Sorry 4th beam at slab step down.

Quote (Thermopile)

If I heard the Penthouse roof crash down and got woke up in middle of night, the last thing I would do is call 911.

I would get my ASS moving fast

If the roof collapsed several minutes before the rest of the building, more people from the upper floors would have been woken up (and escaped) as a result. There’s been no indication that that was the case.

Spartan5, please keep firing to poke holes in the roof first theory that some folks believe may be near top of possibilities. It is our back and forth that roots out the weak theories. And we still don’t have anything to proof who has nailed it and who is left wanting.

The main problem with the "roof first" theory is that there is no evidence for it. At some point you have to apply Occam's razor, rather than keep adding caveats like "maybe all the people in the top floors happened to be heavy sleepers". Also there were lights on in the upper floors, so it is likely people were awake anyway.

i see the penthouse roof missing, already collapsed in the security camera video. So I have visual evidence from two grainy pictures. Those videos are the best evidence we have to date in public domain.

Quote (Thermopile)

i see the penthouse roof missing, already collapsed in the security camera video. So I have visual evidence from two grainy pictures.

No, analysis shows the whole section has shifted down by the time the video starts. The penthouse level has not collapsed.

The 4th piece is the weak slab to column connections we have seen where we had punch shear of slab.

Quote (Thermopile)

i see the penthouse roof missing, already collapsed in the security camera video. So I have visual evidence from two grainy pictures. Those videos are the best evidence we have to date in public domain.

So you are certain that the first available frame of that video isn't just showing the central stack of the structure already in a state of collapse to the tune of about two stories worth of "fall"?

Even with all of the color-coded line overlays, text boxes, and dot-connecting from previous user posts, my eyes aren't drawn to the "roof is the trigger" conclusion. I personally think that there are more plausible (and boring) plaza-level initiating factors than there are roof-level triggers. But it's interesting to see people's different theories.

Quote (Thermopile)

Spartan5, please keep firing to poke holes in the roof first theory that some folks believe may be near top of possibilities. It is our back and forth that roots out the weak theories. And we still don’t have anything to proof who has nailed it and who is left wanting.

Thermopile… it’s tedious. I’m more of an Occam’s Razor kind of guy.

I mean these residential AC units for instance that “rolled” through a parapet wall and/or plummeted into a concrete slab at 70 MPH but are still perfectly recognizable in the basement on top of the slab they punched through??

To me it’s somewhat of a waste of effort. I see of lot of ideas that are having “evidence” manufactured to support it. And I’m most concerned about how any of this could have happened under the care/watch of a structural engineering firm that was being paid over a half a million dollars for their services to ensure that the building is safe and structurally sound.

Barring something new/concrete coming out, for the time being I’m content on chalking this up to the planters. Or maybe a vehicle in the garage. Otherwise we are straying into “disgruntled resident with homemade shaped-charges” territory.

This is usually a place that I hope to find my daily dose of rationality.

The main reason that I keep an open mind about a roof level failure is the timing. Coincidentally there was work done on the roof within 24 hours of the collapse. Any good investigator would chase down that angle even though it may just be a pure coincidence. Other than the timing aspect, there’s not much evidence at all indicating a roof level trigger event. Just a lot of circumstantial tidbits that are worth noting, but nowhere near being smoking gun evidence.

Since we are all taking turns squinting at the time tok video stills, here’s what I see: planters tilted on their side, with foliage facing the camera (outlined in blue). Planters resting on the plaza slab which has cracked in half. The exposed cracked edge of the slab is facing the camera (outlined in green and hatched) and the darker area below is the bottom of the slab. We see the top of the plaza slab in the foreground (broken edge outlined in green). Red outlines may be remnants of column M11.1 and possibly part of the beam, but I’m less sure about that.

Spartan5, I read that our PE SI, Morabito is managing the core sampling subcontractor (possibly his son's company), and requiring X-Ray of Slab before core sampling to ensure there is no damaged rebar. Yet, Morabito's pictures show clearing they could not have centered better over a rebar before drilling cores, than they did.

So I am glad someone has confidence in the PE SI Wizard....

Quote (Spartan5)

I mean these residential AC units for instance that “rolled” through a parapet wall and/or plummeted into a concrete slab at 70 MPH but are still perfectly recognizable in the basement on top of the slab they punched through??

Nothing stops a Trane.

Quote (bones206)

The main reason that I keep an open mind about a roof level failure is the timing. Coincidentally there was work done on the roof within 24 hours of the collapse. Any good investigator would chase down that angle even though it may just be a pure coincidence. Other than the timing aspect, there’s not much evidence at all indicating a roof level trigger event. Just a lot of circumstantial tidbits that are worth noting, but nowhere near being smoking gun evidence.

Since we are all taking turns squinting at the time tok video stills, here’s what I see: planters tilted on their side, with foliage facing the camera (outlined in blue). Planters resting on the plaza slab which has cracked in half. The exposed cracked edge of the slab is facing the camera (outlined in green and hatched) and the darker area below is the bottom of the slab. We see the top of the plaza slab in the foreground (broken edge outlined in green). Red outlines may be remnants of column M11.1 and possibly part of the beam, but I’m less sure about that.

That's pretty much what I see as well.

If the roof went first on the penthouse, there definitely would have been a fire alarm trigger of some sorts. We don't hear that in any of the calls, videos, or survivor testimony.
If the building is already collapsing in the start of the security video, as we know it already is, wouldn't that put the roof of the penthouse at roughly the same angle as it would be had the roof just collapsed first?

Also, is this argument of the roof first also saying that what ever did fall, managed to make it over the roof wall, stay in a fully recognizable shape, and fall in nearly the identical spot it would have been had it been on the roof, all while punching through the slab?

Precision guess work based on information provided by those of questionable knowledge
Aerospace/Industrial/Medical/Structural
SoFla

Yea I didn’t see the planters until someone had enhanced the photo to just the right lighting and contrast. But once I saw it I couldn’t un-see it.

So bones206, if what you are seeing is correct, we definitely have slab failure before beam total failures

Microwizard,

There is evidence that the pool deck collapsed, but there is no evidence as to its cause. It’s also several minutes prior to the main collapse.

There is also evidence, in the very first frames, that the roof parapet has fallen much further than its adjacent slab to the east. That same visual evidence shows that it sheared free of the M column row, while the next portion of the slab to the east stayed up, supported apparently by the M columns.

I don’t think any of the above is disputed, but if it is, please correct me. The above doesn’t mean the roof fell on the pool deck, necessarily, but I’m trying to line up the undisputed facts first.

I am not invested in a particular theory, but what’s problematic to me is that the lights in some units below are still on, despite the suggestion that the x11 units had already fallen 2-3 stories.

What’s also problematic is that Josh/Building Integrity attempted to disprove an early roof event by claiming that the electrical runs are vertical from the basement. That is clearly wrong. The rest of his theory could turn out to be correct, but right now, it’s going to need some maintenance (which I presume he will do as he’s done before with changing facts).

So that leaves us with an unexplained absence of a very specific roof slab and parapet in the early video frames, along with an unexplained pool deck collapse. How did roof slab K/L/M shear so completely from roof slab M/N/O/P at the M column lines, if M10 had sunk several stories?

Yellow arrow points at M boundary between those slab areas:

Comment on the roof fell theory:
The deck had deteriorated to the point that multiple columns punched through simultaneously.
Debris fell from the top of the building and caused the deck to suffer multiple punch through failures.
My disbelief:
An object falling from the top of the building with enough energy to cause a punch-through of 10 or 12 columns may be much more likely to penetrate the rotten concrete of the deck, without causing a complete collapse.
Or, alternately, the falling object would likely penetrate the deck and leave a large hole, whether or not it triggered a complete failure.
Very little of the debris from the collapsing building fell on the pool deck.
Did something from the roof fall onto the pool deck and trigger the collapse?
Possible but highly unlikely.

Comment on the vehicle impact:
It is known that the concrete and the rebar in the columns was severely degraded.
The objections to the vehicle strike theory may be based on a column of normal strength.
These were not normal strength columns.
I don't know what the original safety factor was, but let's assume a safety factor of two.
As the column degrades, the safety factor drops. The higher the safety factor, the longer the time for the factor to drop to one, but with progressive deterioration, eventually the safety factor will drop below one.
With no safety factor it may not require a high energy trigger to cause one column to fail.
That failure will transfer loads to adjacent columns and slab connections with not enough residual safety factor to prevent a punch through.
Could a vehicle, striking a badly corroded, deteriorated column with almost no safety factor have triggered the collapse?
Possible and highly likely.

Or;
Eventually, in the absence of an external trigger, unequal thermal expansion and contraction may have triggered the collapse.
Possible but highly unlikely.

Another thought on the "soft" concrete and a vehicle impact. This is more of a question than a statement.
With the "softer" the concrete, more of the load must be carried by the rebars.
If a vehicle impact crushed the soft concrete, could it also have bent some of the rebar out of the vertical plane and taken the load bearing capacity of the column below the actual load?
Comments invited on this possibility.
I have seen very poor concrete and I have witnessed concrete samples being taken inappropriately. (As the inspector was placing the sample cylinder in the trunk of his car, the mixer operator was spinning the water valve wide open to increase the slump. The test strength of the test sample had no relationship to the actual concrete strength as placed.)

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

Js5180, I see parapet and perhaps penthouse cantilever missing, and perhaps the lower paraphet, and cantilevers in the middle area. I have studied similar picture angles of building before collapse, and I see the middle cantilevers and parapets in plane with the East ones.

Regarding the HVAC units falling theory, the great number of units dangling off the still-standing wing, by what appears to be their electrical or refrigerant lines, indicates that they wouldn't readily roll off the roof. Even the sudden jolt these experienced as they were tugged between their roof attachments and their elec/freon lines wasn't enough to bring them down. Perhaps something else rolled off, but the HVAC units seem unlikely.

I found this interesting photo taken June 30:




spsalso

Would racking of structure from construction next door, and 40 years of under-nourished slab and column connections caused enough deflection and flex to make rebar fail due to work hardening and salt water decay?

Quote (So I am glad someone has confidence in the PE SI Wizard.... 2thumbsup)

This showed up in my earlier post where he was using less than optimal concrete strength and 3/4" cover for repairs... gotta shake your head sometimes.

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

-Dik

That rebar wasn't coupled together was it?

Precision guess work based on information provided by those of questionable knowledge
Aerospace/Industrial/Medical/Structural
SoFla

Another piece of evidence against the roof collapsing first, that I haven't seen anyone mention yet: no fire alarm until during/after the collapse. The garage was the only floor without a flow switch per the 1979 plans. A collapse anywhere would have broken a sprinkler pipe. Breaking a sprinkler pipe anywhere other than the garage would have activated a flow switch, and set off the fire alarm. Only a collapse in the garage could have broken a sprinkler pipe without setting off the fire alarm.

Quote (Thermopole)

Would racking of structure from construction next door, and 40 years of under-nourished slab and column connections caused enough deflection and flex to make rebar fail due to work hardening and salt water decay?

Work hardening unlikely. Salt water decay, without a doubt.

Precision guess work based on information provided by those of questionable knowledge
Aerospace/Industrial/Medical/Structural
SoFla

I can't understand no flow switch in the garage as that is where I would worry about sprinkers being set off by a car fire.

Quote (mb3928 (Electrical))

Another piece of evidence against the roof collapsing first, that I haven't seen anyone mention yet: no fire alarm until during/after the collapse. The garage was the only floor without a flow switch per the 1979 plans. A collapse anywhere would have broken a sprinkler pipe. Breaking a sprinkler pipe anywhere other than the garage would have activated a flow switch, and set off the fire alarm. Only a collapse in the garage could have broken a sprinkler pipe without setting off the fire alarm.

The penthouse wasn't yet in the plans in which the garage had no flow switch, at least not on the page I posted.

I am not in Florida, and the Surfside Document Link has been unaccessible from my location for several days.

This is URL I am getting 404- File or Directory not found.

https://townofsurfsidefl.gov/departments-services/...

Have they moved the files to another location, or is site down, or have Politics intervened after reading this forum???

Thermopile - exactly. The floors are still in plane.

Mb3928 - Did the alarm EVER go off?

If the garage had a deluge system, a broken water pipe may not trigger an alarm.
Some deluge systems use open sprinkler heads and a second dry, air pressurized pilot system.
If a head on the pilot system operates, the dropping air pressure allows a water valve to open and supply water to all of the wet sprinkler heads.
Deluge systems are often used for vehicular areas. A typical system only supplies water to the head that has overheated. A deluge system supplies water to a zone including the area of the head that triggered the flow.
A flow switch is not required. The alarm may be generated by a limit switch on a part of the main water valve, and a broken water line may drain accumulated water but it will not initiate the main water flow.
The alarm may also be initiated by a pressure switch responding to the dropping pressure in the pilot line.
This may also start an auxiliary pump.
Don't assume that a broken sprinkler pipe in a parking area will have the same result that would be expected in a building sprinkler system.

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

If that white object on the floor isn't a column, where is the column? It seems pretty unlikely that it fell behind column 27, as there's nothing pulling it in that direction. The pool deck near it also fell straight down, and wasn't pulled by the column anywhere. The column is really the only object that we know exactly where it should be, and it's missing. In my opinion, that's the only really interesting thing about that tiktok video since it's such low resolution. Also, column 28 must at least be partially in this photo because of it's proximity to column 27, and we know that one was a sheer puncture.

Is there a reasonable explanation for why half of the column would be smashed into bits if something fell from the roof or if the building suddenly deteriorated beyond some small cracks that day? It seems to make the roof theory the most implausible one. We get a good view of this column in the 2020 tour too and it looks like it's in great shape, same with the columns closest to it. No matter where you think the column is, in the tiktok video it looks like it was completely separated from it's rebar down below. What could even cause that? This column was barely under any load, and the column under load is still standing. Good point on those white rocks too, it would make more sense if they were from column 27.

I think if you look closely you can also see the straight yellow line of paint near the bottom of that column, but that would just place the column even further from where it should be if that's the case. Something more like this, with mostly the top missing. Perhaps the top of it stayed attached to the horizontal column above and that's why we can't see all of it? But I can't quite make sense of it separating from the rebar completely at it's bottom, and it being so far from where it should be. There just isn't enough rubble near it to have pushed the column around at all.


And that surveillance photo isn't proof of much, since the video doesn't start at the beginning of the collapse. It's impossible to know for sure what happened in the seconds before it.. it's just a guessing game when it comes to the roof first theory because there's so little proof that was the case. Most people report only hearing two smash/crash/boom sounds before the building completely collapsed.

Thermopile, you can find them here now - https://surfside.one/public-records-search/

No clue why, but that site was setup a day or two before they took the other one down so it was probably just a migration to a better site for them.

Quote (Js5180)

I am not invested in a particular theory, but what’s problematic to me is that the lights in some units below are still on, despite the suggestion that the x11 units had already fallen 2-3 stories.

No more than 1 story. As you have seen the analysis on youtube by Building Integrity, you have seen he accounts for all the upper floors - there is no collapsed penthouse, it is right there in the image. We can't see well enough to see that the parapet wall is still there, but it is not obviously missing.

Josh made an error wrt the electrical wiring, but his statement that one frame later (40 milliseconds?) the lights go off anyway. That doesn't seem unreasonable. To make the roof collapse work, something on the roof has to come loose, jump over the parapet and land at the exact right spot below to weaken the patio deck. That seems far more problematic than explaining the lights staying on a fraction of second longer than might be expected.

Building Integrity also does a great job analysing the roof and showing it was not overloaded. The argument that drilling roof anchors or a proof test weakened the roof is just speculation, there is no evidence. While work on the roof might be a good place to start an investigation, it turns out there is nothing in it and it was indeed coincidence.

The simplest theory that fits the majority of known facts is a collapse initiated in the basement. Making the roof collapse theory work requires too much speculation about events we do not have clear evidence for. It really seems like trying to make the facts fit a theory. At the very least, it is premature based on what we know so far. It's possible the investigation will find a smoking gun in the rubble, but there is just nothing significant enough right now.

I sketched down some of my thoughts on the pool deck collapse, trying to tie together what is known. More questions than answers. Seems that there are at least one too many variables right now, which cannot be answered without further video, eyewitness testimony, or forensic evidence. There should be more information once they get to the bottom of the debris pile. One thing is certain when they remove the debris, they should be able to quickly rule out/in a sinkhole below the actual building foundations. Either the pile caps below the garage slab are still there or they aren't.

JBourne,

I wouldn’t expect to see columns laying intact or even in pieces on the ground. They have rebar at both ends. That isn’t really a likely failure mode for RC columns. If this was a stone church, then yes.

The missing column is curious, but there are many possible explanations for it. First, it could be hidden by all sorts of non-reflective debris, like topsoil or plants. Second, it could be hidden by a hinged piece of slab. The picture is simply too grainy.

And remember - to the extent that I’m suggesting a roof event, I am not suggesting it as a trigger. I am only stating that the absence of the K/L/M roof slab, the in-plane appearance of the floors, and the lights being on all work against the theory that the M column descended first. The answer to that doesn’t lie in the basement pictures but in surveillance video and the roof framing plan.

Hello all, I've seen it mentioned over and over that no alarms were sounded until the building was in active collapse. However, it was reported very early on that there was in fact an alarm that sounded prior to the collapse, and this is why emergency crews were already en route when the final collapse occurred. Whether this was an automated alert or someone pulled an alarm box, I don't know (anyone familiar with Jefferson alarm services?)

I know I saw this reported on multiple platforms in the first couple of days afterwards, but it wasn't repeated much as more information came out, I had to go looking go find it.

https://www.washingtonpost.com/nation/2021/06/24/v...

Has it been 100% confirmed the column is missing in the tiktok video? Just because we don't see it, doesn't mean it's not hidden behind a fallen, hinged section of the upper deck, prior to the failure of the structure.

Seriously, is it not possible that the already weakened structure simply failed due to the additional weight of inches of water over the pool deck? It doesn't have to be some freak accident. Would lend to the deck simply falling down, and hinging on columns attached to the building before ultimate failure. Weather data for the area does confirm at least, at the very least, 2" of rain in the days leading up to the collapse. Assuming a lot of it did drain away, and only half an inch is left on the failed waterproofing of the collapsed section. Basing some rough dimensions off of the pool furniture, lets say that's a 63'x49' area.

96,000lbs of water just sitting there, on a weak structure. I do believe between the hours of 9PM and 12PM leading up to the collapse, gusts of wind 30-45 mph were recorded.

I don't really know what damaged, poorly draining, overloaded flat top structure can handle tons of weight constantly collecting on it day in and day out.

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

Quote (waross)

If the garage had a deluge system, a broken water pipe may not trigger an alarm.
Some deluge systems use open sprinkler heads and a second dry, air pressurized pilot system.
If a head on the pilot system operates, the dropping air pressure allows a water valve to open and supply water to all of the wet sprinkler heads.
Deluge systems are often used for vehicular areas. A typical system only supplies water to the head that has overheated. A deluge system supplies water to a zone including the area of the head that triggered the flow.

My point is that 1) the 1979 FA riser doesn't show a waterflow alarm of any kind in the garage, 2) there is evidence of significant damage in the garage before the collapse, and 3) there are no reports of a fire alarm going off until during/after the collapse. That's not ironclad, but taken together, those facts are one more piece of evidence lending credence to the initiating event happening in the garage/pool deck area, not anywhere else.

Js5180, there just isn't enough debris to completely hide the column. Do you have any ideas on what else that white object could be? I find it curious that some people think they can see rolls of roofing paper in this photo, but not a column. I just don't see how anything falling from the roof could detach a column from it's rebar at the base, and throw it too far away from that spot to be identifiable. Also, I think it's really obvious which column descended first from the ring video.

arbitraria, I heard they were already in the area, and Gabe Nir was the one that called 911 at 1:19 to alert them. The only reports of the fire drill going off seem to be after the collapse. Maybe the security guard pulled it, but it didn't sound across the entire building because of a short in the basement or something?

Demented, If you watch the 2020 tour video.. that's exactly where it was. They were all an equal distance apart and are the same size there. It's definitely missing. We also can't entirely see column 28 even though we know it stayed standing, which hints that the object above it is the pool deck and it hasn't completely collapsed down to the floor there.

Microwizard,

I am confident Josh will address the error, but wire and conduit don’t stretch. The vertical feed was a fairly critical part of his analysis. His theory needs to be refactored. He may end up at the same place but you can’t just skip over that part.

As for how a roof collapse would take place, I believe that at some time before the first frame, the penthouse roof collapsed, hinging at the column M line. This could have happened as late as the second before the video starts, but it’s very difficult to prove that it didn’t happen at some point in time. The penthouse roof slab has clearly separated at the M line. Did it shear off and drop straight down? Did it hinge?

Had that event happened independently of the main collapse, the parapet wall was definitely a weak link and it would provide enough energy to damage the pool deck in the manner we see and then weaken the beam between 10 and 11.1. In fact, if there had simply been a strong enough vibration nearby, I’d expect the parapet to be the first major piece to fall, owing to its position way out on the cantilever.

The roof
Anchors don’t seem to be installed very good.

• https://files.engineering.com/getfile.aspx?folder=97b89e94-48eb-4858-9342-1

What was the plaza
Designed for? A lot of sand on top of it.

I am not backing or discounting any theory. But, if a car /truck hit the column with enough force to completely detach it from the floor, wouldn't it have followed the column? In other words, why isn't there what is left of the vehicle resting against the thrown column? I keep getting drawn back to the unknown cylindrical object where the column should be. But my mind can't make it look like a car part. I must be missing something.

JR97.

What I found interesting in the above photo:

Yes, the two heavy rebars meet at the joint. Perhaps it is acceptable practice to do this for one of four bars passing through vertically? Concrete guys, of which I am not, would know.

But also:

It was posted on June 30. That means that some or all of the parts of the building were being relatively carefully kept off site, for evaluation. As you would expect, but ya never know....

Also, of course was the amount of rebar going horizontally (formerly) through the joint. I can see only one piece coming out of the (now) top, with no places evident where it had been snapped off cleanly. This then looks like one piece of bar where there should have been six. The facing side seems to be similar. Again, perhaps the location of this particular joint only demanded a small amount of rebar. Concrete guys?

So far, this is the ONLY photograph that I've seen with good definition and up close to the subject.


spsalso

The lights can possibly stay on with M9.1 being the effective origin of the building collapse if the slabs remain continuous and just hinged / folded across to the elevator shear wall. I'm not certain, but I think the power runs from the north end of the shear wall, in conduits embedded in the slabs, and we just need them to stay attached for the first few frames of video. It seems conceivable you could maybe get a floor or two of drop in the x11 bays, with the x10 bays gradually hinging down before detaching. If there's something like a 60–100 amp supply to a panel in the apartment, those heavy cables would require a good bit of force before finally breaking.

https://res.cloudinary.com/engineering-com/image/u...

What I see with the cue, is I see top portion of column 28 upside down, standing on j-Hook rebars near corners.

Anybody else?

Thermopile, 28 is the one that puncture sheered and was still standing. The missing column is the one between 27 and 28.

Quote (jbourne8)

I do understand that is where it should be. My point is it's too grainy of a video and there's no actual distinguishable items other than possibly a planter, and rubble that appears to be pavers or CMU. It is possible it his hidden on the other side of the decking that collapsed. There is very obviously debris behind the column location, closest to the garage ramp. If the decking collapsed and hinged behind that column, especially with little light and shaky grainy video, we very much likely wouldn't be seeing it at all.

If this 5 seconds of zoom in is the only proof currently of that column being missing, I think we need to all take the missing column theory with a grain of salt.

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

Sorry quoted wrong column number, but I still see top of column siting on rebar cage from where beam interfaced into it

update: Definitely gate bars are giving me an illusion of the vertical column corners, so not sure anymore what I see

Probably 200A electric service per condo or more if they have tankless water heaters. My Steibel 21kW tankless has two 50A breakers for total of 100A. For a large family you need a 36kW 180A tankless meaning electric panel over 200A. Or they could have natural gas either per unit or central.

If you squiint really really really hard at the tiktok video, lights and shadows might make some sense.

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

Murph,

I would agree - if there was hinging that didn’t break the floor completely off, the power still reaches the unit. The other possibility is that there is much more hinging along maybe the 8 columns than we realize. In other words, the corridor was intact, the southern side of the units hinged downward, but there was still a connection.

The wire to the unit panels is unlikely to be cable and more likely to be conduit with 2-3 wires in it. I don’t believe, from the pictures, that the conduit was embedded. The corridors had drop ceilings, and the conduit comes through the shear wall just below the slab, according to the pictures.

I’d be curious to see a diagram that keeps the conduit intact for a few seconds.

jbourne8, thanks for the updated link

Quote (Thermopile (Aerospace))

Anybody else?

Well I think I see j shaped rebar, but then it's all subjective. I have changed my mind on the roof paper rolls. "They" seem to be inflection of the enhancement level shift on what is really the edge of the fallen slab in shadow. But what I "see" now is the base vertically of the broken (missing) missing column where it should be with sheer damage at about the height of a car bumper , or slightly higher - where it ends. But like has been said it's grainy. Perhaps someone could enhance with the intent of bring out that detail.

Quote (Waross (Electrical))

If the garage had a deluge system, a broken water pipe may not trigger an alarm.
Some deluge systems use open sprinkler heads and a second dry, air pressurized pilot system.

You have to remember that this is in Miami and dry systems are not required, whether never gets that cold. Besides, deluge systems are not normal in parking garages any place, they are mainly used in industrial complexes. In cold climates parking garages have either a dry system (similar to a deluge system like you described but when one had pops the system fills with water and heads open individually if required) or they have a normal sprinkler system that's filled with an antifreeze solution.

It's still interesting that if the collapse happened like some people are speculating the fire alarm system didn't sound. I obviously don't know the codes in Miami but most places require annual system checks where flow switches are tested to ensure that the alarm will sound, this is done by opening a test valve at the end of the line.

I still can't get over that fact that everybody is seen so much in these pictures. They are just seeing what they believe supports their hypothesis of how the collapse started. We have no definitive facts at this time kindness what the sequence of events was. Even the information we have from tenants is only speculative because it's a proven fact that people are not good witnesses in many cases. Especially in a state of panic I don't remember the sequence, timing or other facts of the event.

I guess I am totally confused. The video with the water streaming down was taken from the north side of CTS. How did anything from the vicinity of the elevators get into the garage and break a pipe on the north side of the building?

SF Charlie
Eng-Tips.com Forum Policies

Cringe-worthy interview with a real estate agent parasite about a week ago. The giggle at 1:30, the mention of "low maintenance" in the sales pitch at the end -- it's all sickening. 15:20 on is particularly insulting to viewers. "Don't be afraid of condos." "Bring your flip-flops!" They get 6% of the project cost to take some photos and unlock the door to "show" the property. They pretend to be legal experts, but they write themselves out of almost all responsibility by passing that on to the sellers and buyers.

https://youtu.be/MFTRfsRTpZE

Video still from the Miami-Dade Fire Rescue behind-the-scenes look from yesterday. I wonder what will be left to analyze as it does appear that the area of interest regards the collapse has/is being addressed with heavy machinery and cleared. The picture quality of the video unfortunately was poor and I have been unable to find a better quality image. But this does show continuation of the clearing of the plaza deck area to get down to the garage level, removing the vehicles and all the debris.

Another photo to explain the area near the pool has looked like this for some time…this is an image taken prior to the 4th when the rest of the building was brought down. Again photo quality not the greatest.

Quote (Thermopile)

Spartan 5, you have a concrete and masonry parapet wall surrounding roof, that is around 42" high to deflect wind from blowing outdoor units around

I have a nearly solid 72" fence around my backyard. It does not prevent wind from blowing things on my patio away during tropical storms, not to mention hurricanes.

Having said that, has anyone done an overturning analysis of the HVAC units? Aren't they fairly heavy and most of the weight is at the bottom?

https://res.cloudinary.com/engineering-com/image/u...
What I find interesting about this picture is that the anchor on the left side still has concrete attacks to it whereas the one on the right doesn't. I didn't see any documentation about what type of anchor they were using but the left one certainly looks like they were using a epoxy type anchoring system and the one on the right doesn't. Epoxy based anchoring systems are designed to be stronger than the concrete which obviously with the case here. Normally you would expect a large hunk of concrete to still be attached to the anchor but we are only seeing may be 1/4"-1/2" of concrete still attached which tells me that the concrete itself was extremely weak and deteriorating. I really can't think of a good reasons that we are not seeing anything attached to the right hand anchor of the possibility that they just stuck it in the hole without any epoxy!

Quote (SFCharlie)

I guess I am totally confused. The video with the water streaming down was taken from the north side of CTS. How did anything from the vicinity of the elevators get into the garage and break a pipe on the north side of the building?

It's taken from the north side, but you're seeing all the way through to the south side. On the left of the ramp, the full height wall is the stairwell, and the far side is aligned with the central corridor. The column at the end of the half wall is M8, in the middle of the south side apartments. The column beyond that is M9.1, and the southern wall of the building. The pipe break is roughly in line with the southern wall, below the x11 apartment stack balconies.

bones206, they look more like rocks in the video itself than they do in the photo btw. Also, the columns were an equal distance apart.. including that one on the ramp itself.

Quote (julootamu)

julootamu (Mechanical)11 Jul 21 19:05
Probably 200A electric service per condo or more if they have tankless water heaters. My Steibel 21kW tankless has two 50A breakers for total of 100A. For a large family you need a 36kW 180A tankless meaning electric panel over 200A. Or they could have natural gas either per unit or central.

The building was Three phase Y, 208V/120V.

Leaving out the penthouses, each unit had a 125A main breaker.

Each unit had a 208V electric range, water heater, AC/heat [?], and optional dryer. Plus, of course, various 120V equipment.




spsalso

Quote (jbourne8)

bones206, they look more like rocks in the video itself than they do in the photo btw

Just watched the video, and agree with you those white spots are stationary objects. But I still see the water level the same as in the photo.

Quote (jbourne8)

Also, the columns were an equal distance apart.. including that one on the ramp itself.

Sym P. Le did a nice job earlier showing the perspective of where we would expect to see column M11.1. It's pretty much exactly where I see it broken into multiple pieces. It's not the exact angle or perspective, so it's slightly off, but it leaves little doubt in my mind that we are seeing the remains of column M11.1.

Also note you can see the white license plate of the same car in both photos.

Hello, I'm new here o/

I've been following y'all along these threads for a few days now. As we're real curious as to what's beyond the parking garage gate, I took a look at the 40 Yr Review Plans. I noticed there's several pages regarding the adding of a new Generator and Fire Pump, and along with that the need to reinforce the Generator Room floor because the new equipment is quite a bit heavier.

Do we know if this work was completed? Because the Generator room is directly over the Garage Ramp.
Link
Link
Link
Link

This last link reflects new piping which I believe was added and we see them here:
Link

Investigate Eric Zion:

(1) We need an interview with Eric Zion AND his wife Tamar in the days after the collapse. This is the man who with his wife arrived home from a trip at 10:30 pm and then immediately left to check into a hotel. He came back and spent an extended amount of time gathering things for an overnight at a hotel, when presumably he already had his toothbrush in his suitcase!

(2) What car was he driving? What was its condition, prior to the demo of the remaining portion of Champlain Towers South? What space was it parked in?

(3) Which hotel did he check into? Did he tell the clerk why he was there? Did he seem nervous? Would he have to pay for parking at that hotel? Did he have another vehicle parked on the street nearby that he switched with the car that crashed into the column?

(4)

Quote (Redditor 'phantomtypist')

<<First noises began at 12:30am. ( Observation: Eric Zion said he parked his car at the Garage at roughly the same time and left in his scooter short after. How did he not see the collapsed deck? Would be useful to know what parking spot he was assigned and see if it is near the possible locations for the first collapse. https://www.wlrn.org/news/2021-06-24/i-felt-the-en... >>

(5)

Quote (https://www.wlrn.org/news/2021-06-24/i-felt-the-en...)

"A stroke of dumb luck might well have saved Eric Zion’s life. He lives in the Champlain Towers South building and he said he got back from a trip at about 10:30pm Wednesday night and, for some reason, the lights were shut off in his apartment. He doesn't know why his power was out but it pushed him to make a decision that he and his wife were going to rent a hotel room in the neighborhood just for the night. They planned to figure out the power situation in the morning.

“We drove out at like maybe 11:30ish, went to the hotel, took everything out, and then at approximately 12:30am, I came back to return my car to the parking lot. Then I went upstairs to get my scooter and I was probably in the apartment for 20, 30 minutes so I probably left like 12:50, close to 1:00,” Zion said.

The building collapsed at about 1:15am.

“I went to the hotel. I don't know anything happened until I saw, like messages come up on my phone from people in the neighborhood,” said Zion. “I was like, ‘No way. I was just there.’ Like, how did that happen? So then I took my scooter and I came here and I'm like, 'What?' And I was literally just there when I put my car in, the whole garage collapsed. So my car is totaled. But like, you know, it could have been me.”

(6) Here's the timeline and some details from Reddit:

Quote (Redditor 'phantomtypist')

<<Eric and Tamar Zion came home at 10:30 and power was out in their apartment on the uncollapsed side.

They left at 11:30 for hotel.

Eric arrived back at the parking garage at 12:30am

At that very moment, Sarah Nir begins hearing "construction" noises from the garage at 12:30am.

Sarah Nir eventually goes to the security guard in the lobby to complain.

Between 12:30am and 12:50am/1:00am (Eric couldn't exactly recall) he was up in the apartment to get his scooter and then leave back to the hotel.

While Sarah Nir was with the security guard, the pool/patio deck collapsed at 1:14-1:15am. At least part of it. Sarah and the security guard mistake this for an earthquake. She immediately rushes back to apt 111. It is unclear why the security guard at this point does not start notifying the residents or pulling the general fire alarm. There are now 7 minutes until full building collapse.>>

Think about this scenario: Eric Zion arrives home, is tired, and in parking slams into a column (brake/accelerator mixup -- happens all the time). Column falls, but not on his car. He leaves for a hotel because it doesn't take Einstein's son (a civil engineer) to figure out that a building that is missing a column in the garage is unsafe. He checks into hotel, but wants some of his valuables from his apartment. You know, the evacuation files, jewelry, mementos of his parents, etc. So he goes back and leaves car, then departs for the safety of a hotel on his scooter.

He was probably just hoping that he would not be blamed for crashing into the column. I'm sure he'd be charged about $15,000 by the condo board to replace it, and he may have been held liable for displacing residents once the damage was noticed. Who can afford that? He probably didn't want to pay for the property damage, even with insurance. He may have hoped that the column was not visible on the security cams, and it probably wasn't, based on descriptions of the system and it's focus on entrances and elevators, etc.

Thanks to all who kept coming back to wonder about "the guy who left earlier in the evening to check into a hotel". I hope investigators are exploring the potential precipitating event of a crash into a column.

I do not believe the generator was replaced yet. That would have required some of the offsite parking the building was somewhat requesting, along with replacement of the upper pool deck slab, waterproofing, and pavers. I need to look through the restoration plans again but I'm pretty sure the board didn't even vote on funding the generator yet.

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

bones206, that picture isn't of the CTS garage btw.. and it's also not lined up properly. Note the center of the second column (27) in both photos.. it's not centered, which pushes the rest of the columns further right.

It seems plausible that the missing column could be hiding under the large planter area though.. although it makes no sense that it was pulled in that direction when we know nothing collapsed over there. But I'm definitely not a structural engineer.

NOLAscience, can we avoid the witch hunts in this forum? Leave that part to the cops. It's one thing to suggest that a car crashed into it, but it's another thing to start throwing names around. We know almost nothing about these people.

I believe that photo is from the CTS garage. See Sym P. Le's post on 10 Jul 21 22:58. If you account for the difference in angle, the columns would look to be spaced closer together in the viewpoint of the tik tok video as compared to the google earth photo.

NOLA,

Nobody is driving a car anywhere after slamming into a column at 40 - 50 km/h.

First the crumple zone will have wrecked the engine. Its not going anywhere. So I dunno if he did it or not.

People keep drawing M11.1 as being the same size as M10. Its not. Look at the building drawings. Its 12x16. Its 4 inches thinner on the side that would make it dangerous to a ramp collision.

I cited a real study which tested vehicle impacts with columns. 12 inch / 30cm column was bottom sheared at 50km/h. Thats ideal strength concrete. I think a car could damage this column at a slower speed.

The ramp is 64 feet in length. The column is another 40 feet away. How fast can a car accelerate down the ramp into a column? Its almost precise. The vehicle would continue beyond the impact. Somewhere down the back?

Debris from roof is incapable of destroying M11.1 a vehicle however is. Proven by real testing data. 50km/h is all it takes to bottom shear 30cm column.

Ah yea, he says that's from the north garage there. The garage layout is a bit different there too btw. Personally I wouldn't bother comparing these two images as they're from such different angles.. drawing it out is more likely to be correct. But this is more how the photos look when you center the columns and flatten it a bit so they follow a similar angle to the tiktok video:


They overlay perfectly then too, and it's pretty obvious about where the column was, and 28:


But yea.. it's sloppy and I don't really like that way of drawing it out myself. The way this is flattening the image makes the CTN garage columns much skinnier in this pic than they actually were too, so it only marks the center of the column.

Crazy enough too, I compared it to my earlier drawing and it's perfectly centered.. I wasn't actually expecting that because this style of drawing is so sloppy.

jbourne8 - I didn't catch that it was the garage of the other building. That does makes a difference...

I kind of buy what you're showing for the alignment. Just for argument's sake, what if column M11.1 broke and toppled to the right? Couldn't that conceivably match what I outlined as the broken sections of M11.1?

Quote (AutisticBez)

Ok, it didn't take out a column (though in the condition these columns were in, who knows), but perhaps it jarred the column and the (1) insufficient rebar that has been deteriorated over time, (2) lack of drop panel and additional rebar connecting column to deck, (3) overloaded deck (from heavy vehicles and water from recent rains in 3" of pool deck over waterproofing collapsed a slab, or at least created a crack. He says to himself, "I am not sleeping in this building tonight."

"Power was out in my unit" is just his cover story for not sleeping in the building. I bet the power company can verify if power was out to that unit before 11:00 pm.

Maybe he just saw the planter had fallen from the pool deck into the parking garage, and he said, "I'm not sleeping in this building. It's falling apart." BUT he didn't warn anyone and he doesn't want to catch hell for that.

His current home address is in NYC. That is a two-day drive. Makes sense that he may have been tired after driving for two days and arriving at 10:30 pm.

EDIT TO ADD: His home address is important if this is where he was returning from. I didn't invent this information. It came from https://www.fastpeoplesearch.com/ .

I was having a hard time following the letter/numbering for the columns really, since I don't normally work with building plans. I think a few other people might be having the same problem too, and I do make a lot of quick and dirty diagrams for work.. so I drew this one up so I could follow along with that part:


And hm.. it seems too far back in the room to be M11.1/the missing column? I can't quite make sense of it laying across the top of the planter from the other side if it is M11.1. Seems like it'd make more sense that it's under the planter/slab and out of sight.. or it's that white object laying on the ground to the right. I'm sort of convinced that those two pieces of broken column or slab aren't actually the same column and they just look like they are from this angle.

NOLAscience, why are we posting people's home addresses? Come on. Eric Zion wasn't even the last person who left the garage that night btw, two people from Argentina were and they quickly got on private flights afterwards. If you're going to chase after anyone, why not them?

And fair enough.. I figured horizontal column/beam is all easy to understand language but perhaps not heh.

If it toppled to the right, wouldn't the column be under the pool deck, and not visible as debris in the stills or video?

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

Demented, I don't think it's obvious how much of the pool deck has collapsed in the tiktok video, since we can't see column 28/M12.1. It seems like at least some of the pool deck is still standing, or not on the ground. What's always confused me a bit too is that the lighting looks the same deep into the garage as it does up front, which seems to hint that garage lights could still be on and in tact at this point. The light at the base of the garage ramp between the L and M columns seems to still be on by the light pattern you see on M8.1. I have a hard time believing we're seeing moonlight back there that's just as bright, but it's all very open to interpretation.

Depends on the sequence of events I guess. I'm not married to this theory, it's just what I think I see squinting at the enhanced tik tok video stills.

The angle of the planters (what I believe are the planters) leads me to conclude the slab failed around the 1'-11" elevation drop at the edge of the long planter. The slab would have hinged along grid 11.1 and dropped to the shape of a ramp. That would explain why some of the planters look high up in the photo. Then maybe column M11.1 buckled and fell to the right after the initial slab collapse.

Jbourne8,

See the column inbetween parking spots 27 and 28?

This column is M11.1 its the first column not under the building structure. Which is why its got the .1 at the end. Can you see how its rectangular in dimensions? Its 12 inchs by 16 inches.

It has a tri shaped piling under it into the ground. At the top a beam connects it with M10 along the roof. Which is under the planter boxes.

So on vehicle collisions, its normally the bottom which shears out due to the vehicle being low to ground. So perhaps the beam further pushes the shear at the bottom by holding extra strong at the top?

Also someone should be able to answer whether there is a cold joint between piling and column. This and rusted rebar at the bottom make the bottom shear a high probability.

Maybe car impacts at 10:30pm but takes hours to propagate? Makes sense with Unit 111. Slowly the deck fails until complete collapse?

The problem I have with the car theory is that there is no smashed up car in this video. You guys are suggesting they ran into it, and then their car was still running well enough to go park elsewhere. Also, the tiktok user said that they saw the garage ceiling collapse btw.. I find it hard to believe she missed a car crash with the sound it would have made.

No one knew the building would collapse too, and leaving your smashed up car behind as evidence without ever calling the cops basically proves you're not innocent.. most people would never take that risk on the chances the building might collapse and destroy the evidence. It's all too far fetched.

Quote (JR97)

But, if a car /truck hit the column with enough force to completely detach it from the floor, wouldn't it have followed the column?

Maybe the car hit a column that we cannot see, and that caused the deck above to shear off and fall, tugging on the column that seems to be missing in the TikTok image, and pulling it over. Just an idea.

How lucky can you be?

Eric smashes his car into a column that's GOING to fail, but doesn't yet. Or he'd be jelly. Then, once he's safely out of squishability range, down it comes.

Wow, buy a lottery ticket NOW!


spsalso

Quote (julo)

Probably 200A electric service per condo or more if they have tankless water heaters.

This place was built in 1981. Tankless water heaters were as uncommon as mobile phones in those days. And I found a water heater in an image of the remaining structure. See:

Quote (jbourne8)

Demented, I don't think it's obvious how much of the pool deck has collapsed in the tiktok video, since we can't see column 28/M12.1. It seems like at least some of the pool deck is still standing, or not on the ground. What's always confused me a bit too is that the lighting looks the same deep into the garage as it does up front, which seems to hint that garage lights could still be on and in tact at this point. The light at the base of the garage ramp between the L and M columns seems to still be on by the light pattern you see on M8.1. I have a hard time believing we're seeing moonlight back there that's just as bright, but it's all very open to interpretation.

Not much yet collapsed is my guess. I have a feeling the tiktok video lines up with the "sink hole" opening up that Cassie Stratton mentioned on the phone. I don't believe it is moonlight either we are seeing. It was cloudy, windy, and scattered storms that entire night up and down the coast. The TikTok video is probably a few seconds late on actually getting any column collapse, or anything other than the very start of the deck punching through.

In the TikTok video, all there is, I believe, is the initial stages of the slab collapse, prior to any other collapse, just around or before the M11.1 column. That is why we cannot see the column hidden behind the fallen planters, pool chairs/tables, and upper deck rubble. Some of the upper deck still on and hanging to what little reinforcement is there. This is just above a planter drain location and near a main deck drain that was known to be partially inop and was leaving standing water above the area in the video days before, which in itself is a massive level of water to just be sitting there given it is known to be leaking through and just sitting on the waterproofing membrane. Given that Cassie called to tell her husband of the sinkhole, it seems it wasn't such a huge thing at the time, which also lines up with just some simple construction noises and bangs from below people heard. The Tiktok video then ends here as they go to the other vantage spot but everything happened so quickly, the building was down before the phone was out recording again. This is likely around the time Cassie then started saying the ground was shaking, screams, the deck fully falls, down comes the supporting structure, and call ends. Almost lines up with what we see in the ring cam video.



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

NolaScience posted "This place was built in 1981. Tankless water heaters were as uncommon as mobile phones in those days. And I found a water heater in an image of the remaining structure"

Can't argue with picture of tank in debris. Only thing is that water heaters only last 10 years or so so that water heaters in each condo have probably been replaced at least 3 or 4 times. Some condos could have tankless units when replaced if electric service is a least 200A.

My house was built in the 60's, had at least three 40gal electric water heaters, then a heat pump wtr heater w 80 gallon tank, then five years ago a 21 kW tankless. The heat pump water heater worked best. Tankless not enough capacity even at 100A, 21kW.

What if the car impact is the left side on the corner? Car would end up spinning off the impact, it would continue off towards the rear of the parking garage. If the car clipped the column, the column would definitely be removed and possibly spinning from the impact. Also, what about lower speeds? The rebar in bad condition could shear from lower speeds. What if the original construction is so terrible that this column was just waiting for an impact?

Nobody can explain the loss of the column. It should be a puncture shear like the rest. There is no explainable reason other then out of plane vehicle impact with a column carrying axial load.

Quote (spsalso (Electrical)11 Jul 21 18:39
What I found interesting in the above photo:
Yes, the two heavy rebars meet at the joint. Perhaps it is acceptable practice to do this)

You are right on track. It is NOT good practice to stop one column bar and start another without a lap bar or a coupling/splice collar. In good practice the bars below the floor would be extended ABOVE the top of the slab pour a code specified distance, and new bars started at the top of the slab pour, creating the lap.
We can hope there are many more elements preserved as this one was, because they all are needed to fit the puzzle together. In this failure, most slabs appear to have slipped down the columns like kebabs on a skewer. The column in the photo should have at least some of the slab still sticking to the concrete of the column. A 6 inch slab failing in diagonal tension should leave a cone of concrete 6" out from the column at slab top and tapering to face of column at the bottom of slab, This one just slipped through.
Or - was the column bar torch cut toclear other reinforcing for removal? It would seem more practical to cut the slab reinforcing.
Is that a pour joint in the column section just before the end of the bar on the left? There should be a pour joint at the bottom of the slab and at the top of the slab.

Looks like some pool deck remodeling done around 2013? PVC pipes topside? Maybe the drains were being fixed? Planters still has palm trees here. Palm trees were changed sometime in Q4 of 2017. (Image grabbed using Google earth Date and Time filter)

So, let me see if I've got this right now. A man just flew into Miami Beach after picking up his Russian mail order bride by Amflack's auto-plane. They dropped the couple and their car on the roof. He stepped on the accelerator by mistake and drove off the roof into a stack of roofing tar paper, The tar paper broke their fall, but also the pool deck. Because tar is a viscous liquid, they had time to run upstairs and get a scooter to carry their valuables and a condom in, before the building collapsed. Right?
(Back in the USSA)

SF Charlie
Eng-Tips.com Forum Policies

I saw this video with some commentary. It includes the video showing the water running down into the parking area.

https://www.youtube.com/watch?v=PEPyE2h6P4k

Quote (AutisticBez)

What if the car impact is the left side on the corner? Car would end up spinning off the impact, it would continue off towards the rear of the parking garage. If the car clipped the column, the column would definitely be removed and possibly spinning from the impact. Also, what about lower speeds? The rebar in bad condition could shear from lower speeds. What if the original construction is so terrible that this column was just waiting for an impact?

Why are you so convinced a car knocked the building down? Nobody else is really supporting that theory on this forum or anyplace else that I've seen. Sure it's a possibility as is an ocean liner running into the building but it's certainly not a logical cost is a problem based on all the other information and photos available

Quote (jbourne)

home address

I only listed the street name, and this info is available in a thread on Reddit, and it is public record, which is where the Redditor got it. It's no big deal.

Quote (Mark R)

Nobody else is really supporting that theory on this forum or anyplace else that I've seen.

I support this theory, to the extent that it may be a possibility, and I don't care about any other forums or YouTubers. The possibility cannot yet be ruled out, and we will continue to look for evidence that shows that it happened. If we find none, ever, and we find a plausible explanation for what might have been the proximal cause of the collapse, we will come to the conclusion that a vehicle impact was unlikely to be the cause. However, we accept that, as in many plane crashes, experts continue to debate causes long after reports have been filed away.

Quote (julo)

if electric service is a least 200A

Key word "if" ^^

For your convenience, here is a swimlane diagram that includes the witness interviews of:

• Eric and Tamara Zion (went to stay at a hotel)
• Sara, Gabe, and Chani Nir (111)
• Nicolas Vazquez and Gimena Accardi (parked immediately before the garage collapse)
• Adriana Sarmiento and Roberto Castillero
 (video of the garage rubble)

The sources are linked in the right column.

**************

Edited. Please scroll down for v2.

• https://files.engineering.com/getfile.aspx?folder=1c40b552-3e4e-4b83-bb0f-7

I prefer looking at the un-enhanced photo to compare to the enhanced version. It's also good to go back to the video that is posted in "Miami Beach, Champlain ..., Part 02". You can get a better idea what you are looking at as the camera moves and the light changes slightly on the objects in the garage.

https://vm.tiktok.com/ZMdasA62E/

I wish someone could edit this video and just show the garage opening. Remove all the rest and just play the video with all of the motion removed.

Here's my screenshot. Sorry about the TikTok "Play" button. The image is a bit clearer in the attached downloadable file in my next post.

Link to the slightly better quality image.

• https://files.engineering.com/getfile.aspx?folder=db663db6-cc6b-4759-ac03-5

Does anyone know if the cars that were towed away were the ones parked next to the pool, in the area that became the ramp for the equipment? It looks to me like at some point they removed the pool slab in that area, and made it into a ramp. I'm theorizing the cars we saw towed away were those parked directly under it, and in the way of the ramp they needed to build.

Quote (Vance Wiley)

You are right on track. It is NOT good practice to stop one column bar and start another without a lap bar or a coupling/splice collar.

Is there any chance that this is a brittle failure of the rebar? I can't imagine that the contractor did not lap splice the rebar at all.

Maud,

Do we know where all of these people were parking? It would discredit my theory. Which is important. If stuff was occurring in the building, it was happening around 12:30. There are people coming and going around this time. I'm sure they would have seen a column damaged right? Unit 111 says 12:30, work sounds like it's coming from above. So, this fits in with the roof. But, if it was coming from below, might she not still think it was coming from above? Given that sound would reverberate up the columns around her apartment? You probably won't hear sounds from the parking garage right?

Where exactly do the parking spots line up with the apartments?

Quote (NOLAscience)

Is there any chance that this is a brittle failure of the rebar? I can't imagine that the contractor did not lap splice the rebar at all.

I was thinking the same thing, I've never seen rebar brittle failure but I'm nowhere near saltwater. It seems a little strange that it would be installed without laps however assuming there was any kind of inspection done during the construction. As mentioned earlier it would be nice to see the as built drawings as well as the shop drawings for the rebar.

NOLAscience, posting where someone lives is called doxing, and it can be a very big deal btw. Depending on where you live, it can even be illegal these days. All it takes is copying down someones public info and spreading it around.. if they get harassed due to it, or if they happen to work for the government (way more people do than you'd think these days), etc.. you can run into a lot of problems. Plus, where he lives in NYC is completely irrelevant to the structure of the building.

Keep in mind too that the only testimonies we've heard are the people who've talked to reporters, and most likely there were other people there that only spoke to police, or no one at all. I'll take a look at the video tonight and see if I can edit it down, but I can't be in this forum if this turns into a witch hunt or if we continue to dox people.. it's way too close to illegal activities that I can't be a part of.

Quote (NOLAscience (Structural)12 Jul 21 02:52
Quote (Vance Wiley)
Is there any chance that this is a brittle failure of the rebar? I can't imagine that the contractor did not lap splice the rebar at all.)

As has been discussed, almost anything is possible, but a brittle failure of the one rebar seems remote in this case because the concrete in the zone remains relatively intact and does not demonstrate effects of sufficient flexure to fail the rebar.
As I look closer, it appears the left bar tucks under the right bar and may extend some distance into the right section of concrete, and that would be expected.
This part of the detail may be OK. A bit of chipping could confirm this.

The timeline of Nicolas Vazquez and Gimena Accardi is rather interesting, They seem to be the very last ones to have gone through the parking garage before it collapsed. If my basic Spanish serves me right, they said they parked normally, heard some noise but thought nothing of it/couldn't make out what it was, got into the elevator which stopped on the ground level (an automatic stop on the way up), there, they saw some dust and frantic people who said the deck had collapsed (possibly the people from 111?), heard more noises and now car alarms going off, so they all dashed across the street. Once there they heard a thunderous noise like they'd never heard before, and down came the building.

If memory serves me right, on some TV show the journo said they were staying in 308 and their parking spot was "on the left" of the unit (left relative to what exactly? I don't know). Thus I wonder if the first noise they heard but didn't recognize was already the deck collapsing into the level below, but as it happened it was hidden from their line of sight (say, if the elevator block was in-between), or if it was another noise from the building, much like the undefined knocking some people had heard some time earlier, but when they stopped at the ground floor, dust was already flying. I'm having a hard time piecing together all the timelines right now (from the various survivor testimonies and videos) and making sense of the different noises and their respective times.

Let me grab the link s if I can find them again...

Alright so on this video it's the TV presenter that relates what the Argentine couple said and adds the details about the unit and parking spot: https://youtu.be/wDCBKRWfQTI

This here is the message directly from the guy himself instead: https://youtu.be/yThHXikBav0

If anyone has a better graap of Spanish that what I could string together in the previous message, please go right ahead...

Quote (NOLAscience)

Quote (julo)
if electric service is a least 200A

Key word "if" ^^

As I stated earlier, each unit had a 125A 208V service.

And you really should try not to make up quotes and/or poster's usernames. If you are that sloppy with something that can be checked, it implies the same for all your reasoning.


spsalso

I apologize for being off in the weeds a bit but this has haunted me for 35 years. I had nothing to do with this event but "Who Woulda Thought?"
The use of stainless steel to support a ceiling over an indoor pool sounds like a good idea, right? Not so much.
https://corrosion-doctors.org/Forms-SCC/swimming.h...

To bring this into focus with the present topic, it is common to spec stainless expansion bolts when exposed to weather. Is that a good idea in a seaside environment?

If this is too far astray just trash it. I will understand.
Thanks,
Vance

That column picture with the rebar ends - is that at a floor connection and not the middle of the column?

As for the roof collapse/falling theories. Why didn't the presumably motion activated camera recording start sooner and possibly catch some of the roof falling? If the roof failed and caused the pool deck damage in that tiktok video then that camera should have been triggered by that failure and been recording long before the building started to collapse.

Quote (LionelHutz (Electrical)12 Jul 21 03:59
That column picture with the rebar ends - is that at a floor connection and not the middle of the column?)

I think it is the point where a floor slab intersected the column. The small rebar which is bent over would have extended into something and that supports the slab idea. There is no paint on the column so it was behind wallboard somewhere if it was a column. It could have been a transfer beam - but I assume that would have been painted but that may not be correct.
It would be good to hold final determinations until the member is identified.

2 Thoughts. If the guy spent the night in a hotel because he hit a column, it was to avoid a DWI. If a roof AC unit fell, it may have been unbolted by the roofers.

Quote (NOLAscience)

Sorry about the TikTok "Play" button.

Perhaps it’s easier to use the original video without the edits added for TikTok?

https://youtu.be/ngyKmBjIZig

The background commentary is interesting. Vehicle and building alarms are sounding but it’s extremely difficult to make out audibly.

Quote (NOLAscience)

I wish someone could edit this video and just show the garage opening. Remove all the rest and just play the video with all of the motion removed.

This isn’t perfect. But it’s an improvement maybe.

• https://files.engineering.com/getfile.aspx?folder=5d1a7420-db49-41d8-b7a2-f

Quote (AutisticBez)

12 Jul 21 03:09
Do we know where all of these people were parking? It would discredit my theory. Which is important. If stuff was occurring in the building, it was happening around 12:30. ...
Where exactly do the parking spots line up with the apartments?

Sorry...I haven't yet found any info on parking space assignments.

Quote (The use of stainless steel to support a ceiling over an indoor pool sounds like a good idea)

Some stainless is susceptible to chloride attack... have to check with a materials dude...

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

-Dik

BlakeStr,

Here is the thing, this area is a warm climate area? See, I don't know anyone who would evacuate a family out of an apartment just because the electricity wasn't on. I know a family who live in a real massive house in a cold area in the hills of NE Melbourne, and you know, tree's falling on power lines and nobody can get cars in and out of the area due to closed roads, and they had insurance which enabled them to end up in a hotel. But, I'm guessing this family in this tower hasn't got a hope of claiming insurance for the hotel stay.

It seems a little weird. Oh honey, the powers out again, better go stay in that cheap hotel again. I mean, did the guy even talk to security? Did he make a complaint about the power? Is it weird that he has no power? Come on, really? He's got the worlds most lottery ticket excuse for not being inside a building that has killed 150 people right?

This couple in the elevator right? I mean, they probably had tickets booked to return somewhere? They might not have wanted to stay in town and give an eyewitness account of the incident? I mean, did they have a vehicle? Where is the vehicle? Is it a rental? I dunno about anyone here, but if I slammed a rental vehicle into a buildings column and the entire thing was starting to rain white cement and broken rain water from the pipes, I bet you won't find me thinking twice about trying to get an early flight out of there right?

Seems the people in the garage have literally nothing to say about a falling pool deck and potential damaged column. I'd probably notice a column sitting on it's side 40 foot away from the ramp on the left. I don't think you could miss the thing. So many details and so little eyewitness accounts.

You know, then there is the other side of this, the condo owners association has all the money right? The last thing I'd want to report is someone crashing their car into a building column. I'd want all the blame sitting on the condo board. That's going to be the thing that gets the lawsuits settled in a flash. Driver hitting column equals no massive pay outs.

If you look closely at the video taken from the south during the demolition of the standing portion of the building you'll see an AC unit flying over what looks like a dumpster.

You can see the condensation cloud formed by the gas spewing from the broken freon lines as the unit tumbles in its flight to the southwest out of view of the camera.

This flying compressor should give us an idea of the amount of force required to break the gas lines. I think it's very unlikely a unit falling of a stand as the penthouse roof slab collapsed would experience enough force to break the freon lines. The dangling units shows they're pretty strong, but being launched will break them.

Quote (LionelHutz)

As for the roof collapse/falling theories. Why didn't the presumably motion activated camera recording start sooner and possibly catch some of the roof falling? If the roof failed and caused the pool deck damage in that tiktok video then that camera should have been triggered by that failure and been recording long before the building started to collapse.

I suspect the camera has a sensitivity setting, as many motion activated cameras do. In the video you can see foliage swaying in the wind within a foot or two of the camera. You would have to have the sensitivity turned down to a minimum to avoid it being constantly triggered by that foliage movement. Thus it probably took the motion of a full building collapse to rouse it.

Not sure if anyone noticed this, but slowing down the video, I noticed that a light in an x10 room was actually turned on during the collapse:



I've also noticed that some of the lights appear to go out in synch with the blue flashes going out, but not necessarily the ones directly horizontal to them. Someone mentioned three phases. Are different floors on different phases? Would this mean that appliances like stoves and dryers are 208v, instead of 240v? Would this also mean that every third floor is the same phase, or is that unpredictable?

(EDIT: added arrow)

As far as I know, the original video is the tiktok video. It's only 1.59MB on the tiktok site itself though, so it isn't a lot to start with really.. this is a tiny video. Anyways, I went through and stabilized it as best as I could, and cropped it down. This is the full video, but it blurs out whenever she moves the camera too fast and there's not much that can be done to fix that. I didn't do any sharpening, lightening, etc, because that tends to just degrade videos. Here's my stab at it - https://www.youtube.com/watch?v=CWlbPxbecNI

Some interesting things I noticed.. there is a flashing light on the left wall, so clearly the fire alarm did go off. It looks like the reflection of a strobe light to me. Also, I think on the bottom part of that broken column it looks yellow and changes color in a few frames.. I'm pretty sure we're seeing the bottom of column 28/M12.1 there and it isn't attached to that horizontal broken slab/column/beam.

This frame is sort of interesting too, I'm pretty sure we're looking into the very back of the garage inbetween those last two pieces of the gate grates on the right. Seems like it's probably either the bottom of a wall or a shadow under a car, but it doesn't seem to have any rubble or be part of the collapse yet.. which matches up well with the lighting too. I applied a filter to this pic so it's a bit easier to see.

CTS Collapse Witness Swimlane v 2

Includes updates to the Nico Vazquez/Gimena Accardi details per the videos cited by emtv. They were staying in 308, they parked in the garage "to the left" of 308, they heard a loud cracking sound (previous translations have called this a creaking sound) a few seconds before they got on the elevator, when they exited the elevator in the lobby, they saw dust and smoke and "sunken cars." They ran from the lobby with a few other people, and then the building collapsed.

NOTE: Other than Adriana Sarmiento, none of the witness interviews I have so far found mention seeing any garage damage.

• https://files.engineering.com/getfile.aspx?folder=cb3c1e11-bf1a-4575-8a89-a

Why are we still stalking the victims of the collapse over this silly mystery ghost car theory? There is nothing that backs it up at all.. it's not even a believable theory. I think where people were parking is completely irrelevant, and it wouldn't prove anything even if all three were parked right next to spots 27 and 28.

Personally I hope the parking space info doesn't get out, as this is only going to encourage people to harass them. I'm sorry, but you guys aren't going to catch someone online that the cops have somehow missed. This might be a better discussion for reddit, not an engineering forum.

Quote (Jbourne8)

I think where people were parking is completely irrelevant, and it wouldn't prove anything even if all three were parked right next to spots 27 and 28.

The swim lane shows that that the Zions, Vazquez/Accardi, and possibly also Sara Nir parked in the garage near the time it failed, and did not mention seeing any indication of an accident or damage. The only witness who reported damage in the garage is Adriana Sarmiento, who shot the video of the rubble.

I don't know about you, but most people don't inspect their parking garage for damage when they get home after midnight.

Quote (MaudSTL)

when they exited the elevator in the lobby, they saw dust and smoke and "sunken cars."

If that account is true, it would indicate a larger area of initial collapse of the plaza slab, to include the area where cars are parked. As opposed to a more localized collapse in the vicinity of the planters/column M11.1.

Do you guys agree with that line of thinking?

Quote (Jbourne8)

…most people don't inspect their parking garage for damage when they get home after midnight.

If you drive right past a fresh pile of broken concrete in your garage, and then the building falls down, you might think to bring it up.

Quote (Bones206)

If that account is true, it would indicate a larger area of initial collapse of the plaza slab, to include the area where cars are parked.

Both Sara Nir and Nico Vazquez said that they saw cars. Sara said they were sticking up, and Nico said they were “sunken,” although this may be a bad translation…maybe somebody could check that…the links are in emtv’s post above and in the swim lane.

Anyhow, two witnesses saw cars, so I was thinking that implied they were seeing the surface parking lot had collapsed.

bones206, Yea.. that makes sense. I was surprised to hear that too.. but I can't seem to find that in any interviews. Is there a link to the audio/video somewhere? In this one he mentions they heard a loud noise in the garage, but no cars - https://www.youtube.com/watch?v=zBTnPiI3gLo

MaudSTL, I think this progressed a lot quicker than you think. It sounds like the entire collapse starting with that pile of rubble in the garage took about 3-5 minutes total. It sounds like they were in the elevator at the start of that, so they probably saw nothing. They couldn't have driven past the rubble, as it would have been in their way on the way to the elevators.

Quote (Jbourne8)

They couldn't have driven past the rubble, as it would have been in their way on the way to the elevators.

Exactly my point. Vazquez didn’t mention any collapsed columns, and he couldn’t have driven to his parking space if the rubble Sarmiento videoed had already blocked the entrance ramp. Based on his description, which I hope someone with good Spanish will translate, the garage collapse on the ramp happened behind Vazquez/Accardi, as they were about to get into the elevator. But when they exited the elevator into the lobby, he talks about seeing smoke, dust, and “sunken cars,” and hearing auto alarms before they ran out of the building. He says it all happened within a few minutes.

Actually.. after looking at this tiktok video a bit more, I don't think that is the strobe of the fire alarm light on that left wall. The lights are only on the outside of the building and stretch all the way to the sidewalk. It looks like a car alarm was going off, and it's their back lights that are blinking. Seems very strange that a car alarm picked this up parked so far away though. Maybe just from the boom of the M11.1 column collapsing? Although even that seems odd through so much concrete..

The Argentina group actually said they went up to the 2nd floor in some news report, before the elevator was recalled to the lobby.. so there's a bit more time I think between the events too btw.

Where I live, sound (like gunfire) ricochets off hard surfaces and is very loud. Those hard surfaces don’t dampen sound at all, so it really carries. I have often heard thunder set off car alarms, so a loud crash setting off an alarm wouldn’t surprise me.

Here’s a snip from the interview linked above. He does say the parking lot had fallen and many cars were sunken.

Oh good catch.. I don't know Spanish at all and those interviews are hard to follow. It seems like he's describing the full building collapse though, especially since he says he heard car alarms ringing and saw a lot of dust, and none of that shows up in the tiktok video. Their story is very strange since it's so hard to place within the rest of the stories.. and those all fit together.

And here’s the WaPo story on what Sara Nir saw. This is an archived version.

Link



…and also, from the same WaPo piece, it looks like one of the Nirs noticed Vazquez and Accardi by the elevator.

My Spanish is very basic, but from what I gathered from the interview, they heard a noise as they were getting on the elevator in the garage. Got off in the lobby, which was filled with dust and loud noise. They didn’t know what to think: tornado, attack…it was like a movie scene. They fled the building with others and then noticed the collapsed parking lot and sunken cars with their alarms blaring. They were all in a state of shock gathering themselves for 2-3 minutes when they heard the sound of the building collapse. A sound he describes as impossible to relate.

Dude, it's not doxing to ask where their parking spot is, in a building that no longer exists. It's like, if I tell you I once lived at 9 Kinnoull Grove Glen Waverley Victoria Australia. That isn't doxing. I once lived there a long time ago.

The addresses of people who lived in the fallen building is not stalking or doxing. I mean, if one of these people in the swim lane turns out to have a car that has a giant gapping hole in the front. Surely that's evidence right?

I'm just saying, someone if they hit that column, knows too much, and isn't interested in coming forward. But if someone can get eyes on which vehicle they drove into the building, well, maybe that can be a bypass of their honesty.

MaudSTL, it's hard to know if they actually said that since they aren't quoting them, and reporters seem to be adding a spin onto some of these stories. I haven't heard her say that in the video interviews she's done, which seem to be more accurate.. like this one for example - https://www.youtube.com/watch?v=1gie0XVOFl0 In this one she says that she went to security at 1:10, and that "all of the garage collapsed." But I mean, we know that's not entirely true either.

AutisticBez, I never said that was doxing.. someone posted info on where exactly Eric Zion lived in NYC, which absolutely is doxing. Lots of posts have been edited now, so it's probably hard to read the convo now really. We're all cool now too, your comment really isn't necessary.

Asking about assigned parking spots is what I'd call unethical instead. Imagine a completely innocent person is parked in spot 27 that has a strange story but didn't cause the collapse, and ends up being stalked and harassed because of our research.. that gets you into an illegal territory no matter if you want to call it doxing or not. Some of us have serious careers that we need to worry about, and we can't be attached to any sort of witch hunt. There's absolutely nothing that even backs up this silly car theory. The roof theory is even more plausible than it is.

You are not going to gather any good evidence against anyone online either.. and it's silly to think that's even possible. This forum is about engineering, so it doesn't matter who hit the column.. we're just discussing what could have happened with the building. We can't get into a territory where we start placing blame, or anyone professional is going to have to leave the conversation. Leave that for the police.

My take on image enhancement. Nothing special, although I like the result. Still can't read the license plate though.

Emty's links to Vasquez interview.
They heard noises when going up the elevator to the lobby arriving into a cloud of smoke and dust. Vasquez mentions hearing two times, more thundering noises. He only direction he mentions of these noises was from the parking area.

According to his account, as the text on bones206 06:50 post confirms, it would appear that Vasquez only heard, but did not actually see any damages to the parking area at that time, because that says, "There we now understand that part of what was the parking area had fallen, with many cars sunk."

Since the interview seems to confirm the parking lot slab near the lobby collapsed prior to the building collapse AND noting that those columns exhibited punching shear failure, that would indicate a generally overloaded slab. The strange noises people were hearing could have been one column after another failing at its slab connection. Each time the load would get redistributed to adjacent columns until there was just too much load to go around and a whole area of slab just drops.

No, that quote in the snippet is in the context of them making their way out of the building. He’s saying they got outside and REALIZED that the parking area had collapsed. That’s my interpretation anyways. In the interview he’s giving a chronological account, but he’s obviously emotional and having a hard time conveying the gravity and trauma of it all. I feel quite badly for them.

Sym P. le, I'm having a hard time seeing it any other way too. This is how I see the tiktok video.. and I don't get what else could possibly cause this sort of destruction down there. Just really soft cement from all of the water that was never tested? It seems too extensive and immediate for that.


Also, I don't get how those garage lights are still on if that part of the garage is actually collapsed.. I sort of doubt that's the case. It's far too bright to be moonlight. If Cassondra was in 410 and she saw the pool deck collapse from the edge of 111 to the opposite edge by the car parking lot.. there's no way she would have stopped to call her husband too.. it just doesn't really fit.

This may be a tiny detail, but there are two separate versions of that garage video taken by Adriana Sarmiento. The first is the Tiktok vm everyone has been enhancing, https://www.tiktok.com/@adrianitacastillero/video/...

The second was sent to various news outlets and the NYPost version posted above is vertically cropped. A fuller version is at USAToday: https://www.usatoday.com/videos/news/nation/2021/0...

The difference aside from wider angle and a bit less resolution is they were actually taken at different times - listen to the audio - and at slightly different angles just 3-4 inches apart - observe the parking space # on the column. What takes me back is that a little less data makes that circular "washing machine" below the gate marquee appear as an irregular shape. I think that speaks to the perils of overly enhancing a compressed video frame.

Additionally, several here have suggested the blue-greenish tint in some of the debris may be part of a construction bag used to hold roofing paper, or even planter material. I think that given the "harsh" fluorescent lighting washing out most colors they are more likely the bright patio chairs outside apt 111 that Sara Nir photographed. They appear in the Washington Post article recently linked:
https://archive.ph/ftQTW/a0d19d141755b8de32ec3ef00... Unfortunately I haven't yet found a better view of what is immediately south of column 27 that could block our view of 27-28.

Can someone tell me this is not what it looks like. It the source of the odd green color in the tictok capture. It's just cropped and enlarge with the typical sort of image enhancement. I'm pretty sure it's not a patio table.

Auri, Nice find! I hadn't seen that second video yet.. looks like this one was taken from further away. And that's an interesting point about those chairs. I kind of blew it off as a green tint from the slab reflection, or maybe a green car that's smashed back there.

microwizard, The reason why there are so many different disciplines in here is actually to make it easier for the structural engineers.. it's difficult for lots of them to edit videos, work on photo imagery, hunt through and find all of the endless documents, etc. There were also a lot of questions about the security equipment in the last thread that none of them were able to answer.. which I think brought a lot of us computer guys in here. I think the reason why it's less informative now is because no new information has come out in a few weeks now. There's nothing unprofessional about reanalyzing the little data we have, come on. If you want an expert opinion, go watch the news.. that's never a good thing to search for online lol

Quote (Auri (Bioengineer)12 Jul 21 09:02)

Thanks for the post. These details are not too small and are otherwise easily missed.

Perhaps some don't appreciate brainstorming. It can be tedious. The purpose of enhancing video is to assist in the evaluation, no more, no less.

Quote (Zebraso)

I believe that's Bessie downn for the summer.

Likely a reflection off a wall. In other videos that are poorly lit, cropped to hell, condensed, and squinted at from before the collapse, similar color glows can be seen on the ground and walls. Appears to be the wall just before the hot tub.

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

Does anyone by chance know what the theoretical compressive strength of column M11.1 should have been in an ideal environment?

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

Crack, or exterior cable being run? If a crack, then this could very well explain why the penthouse does appear to be missing in the start of the collapse.

Collapse sending a shockwave down the columns until it transfers the load to the top of the M11.1 column, causing it to overweight to failure?



Edit: Original link to source where I found the image. Actual source and date unknown.

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

I'm surprised nobody else has mentioned the phone conversation that Pablo Rodriguez had with his mother, Elena Blasser, hours before the collapse.

https://www.latimes.com/world-nation/story/2021-07...

"On their last phone call, the day before the tower collapsed, she told him she didn’t sleep well because she was woken up at 3 or 4 a.m. as the building made loud creaking noises."

In a different interview, Pablo said that his mother had told him that the "creaking noise" she heard was so disturbing that she couldn't go back to sleep.

Guess where Elena Blasser lived in the building.



Yes, 1211 (edit: this penthouse is listed as PH-11 and is the x11 apartment layout of the 12th story penthouse floor). The apartment directly below the section of the penthouse suspected of having a roof collapse. What are the odds. A "creaking noise" so loud and disturbing that it woke her up in the middle of the night, less than 24 hours before the building collapsed. A noise that coincided with questionable work by the roofing contractors on the penthouse roof above her.

I think the recovery team is going to find a parapet in the garage, mixed in with debris from the planter it punched its way through. I also wanted to note that the roof scupper in this parapet is also directly above the planter. For 40 years, that roof scupper was inundating the planter and nearby pool deck with water every time there was heavy rainfall. It had actually rained nearly 2.5 inches in the days before the collapse, which is a potential source for all the water pooled on the garage floor.

Js5180 (Computer) commented "I've also noticed that some of the lights appear to go out in synch with the blue flashes going out, but not necessarily the ones directly horizontal to them. Someone mentioned three phases. Are different floors on different phases? Would this mean that appliances like stoves and dryers are 208v, instead of 240v? Would this also mean that every third floor is the same phase, or is that unpredictable?"

Three phase supplies are either provided in 460V or 208V. I'm sure each floor would be the same, as providing different phases on different floors would be impractical and confusing. In this case its apparently 208V. The good thing about 208V is that a connection from of the three wires of the 208V service to the neutral provides 120V single phase service. Two such connections can supply a standard 240V dryer/etc. While the 120V single phase powers lights/etc. There are special commercial appliances available at extra cost that are designed for three phase but I doubt they were required here.

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 have seen many thoughtful comments about codes and regulations, but have not responded because this does not seem like the proper forum for such a discussion. Can we start a new forum dedicated to preventing "engineering disasters", that deals strictly with inspection and repair of existing structures in terms of codes and regulations, so that we can actually help the general lay person?

Quote:

I suspect the camera has a sensitivity setting, as many motion activated cameras do. In the video you can see foliage swaying in the wind within a foot or two of the camera. You would have to have the sensitivity turned down to a minimum to avoid it being constantly triggered by that foliage movement. Thus it probably took the motion of a full building collapse to rouse it.

That's a pretty useless camera if it requires a large portion of a building to move before it records anything.

Quote:

I think it is the point where a floor slab intersected the column. The small rebar which is bent over would have extended into something and that supports the slab idea. There is no paint on the column so it was behind wallboard somewhere if it was a column. It could have been a transfer beam - but I assume that would have been painted but that may not be correct.
It would be good to hold final determinations until the member is identified.

Yes, there is also that piece of bent rebar that could be from the slab. I can see 2 lines outlining what could be the top and bottom surfaces of the slab too. I'm not understanding why a rebar in a column ending in a slab joint would be an issue?

Things like the stove and dryer and water heater would be standard 240V commodity pieces. They just heat a little slower on 208V. The dryer motor runs on 120V, so the drying time just gets extended a bit.

I for one don't care where any of these parked their cars, but I find that knowing about it is no different than knowing where any of the other residents were as they observed/heard the various events unfold. What's interesting about the thereabouts of the Argentine couple's car can be relevant to the time at which the events unfolded from an observation standpoint. They had to go through the garage entrance and literally got in barely minutes before the whole thing came down. When they did, clearly nothing was standing in their way, which means the deck collapse hadn't happened yet, and they possibly didn't register any visible signs that it was about to. Their location is also interesting in relation to the noise they heard prior to getting into the elevator. They heard something but couldn't recognize what it was, and also didn't see anything happen there and then (either because their line of sight was blocked, say, if they had been standing behind the elevator block, or because nothing "visible" had happened yet - cue what bones206 said about load redistribution noises - but doesn't that imply the deck falling is subsequent to whatever else had already been going on, and if so, what was that exactly?), but by the time they got to the ground floor and came across the other panicky people there, dust had been flying already, and supposedly only then the deck then caved. To be honest it's still unclear to me whether the deck gave in as they were coming up, or while they were in the lobby with the others. But if that timeline is correct, and the caving is secondary to the dust flying around, then what's the source of the dust? (Honest question).

As for the wild theories going around. The two didn't observe anything out of the ordinary. I would imagine that if the car-slammed-into-column theory had any credit (which I doubt, personally), they'd have perhaps noticed plastic, glass, metal, car liquids, tire signs – anything from the car, really – that would deviate from the ordinary, and it would have been right on their path. Or maybe they did notice, but given the magnitude of extraordinary things that happened afterwards, they just didn't recall these specific details in their telling... but again, it'd be a stretch, I could think of at least 5 different things more plausible than that. Secondly, I'd also rule out their own involvement (I think I saw a comment here implying that perhaps they could have been responsible instead), there would have been simply no time for them to hit a column, recollect themselves after the fact, and then carry on like nothing had happened - given they barely made it out as is. Those implying they fled shortly afterwards because they had something to hide, they were there only temporarily and weren't owners in the complex. I'd imagine the first thing I'd do, if I were in a city I'm only temporarily in and a building I had no particular relation with came down on me, would be getting back home asap. I'd also imagine, much like for any of the other survivors, that on top of what was made publicly known, officials have collected their statements privately. What we know and what they know might not necessarily have the same depth.

I've read the mulling on "when it was only structural people discussing it". With all due respect, much of what is being done here, at the time being, is speculation. Literally all of what is being done here is, including combing through "hard facts", i.e. schematics and plans. Witnesses accounts are notoriously unreliable, but pretending that looking at plans, photos and documents on the internet isn't is a bit delusional, too. For all we know, things were omitted from documents ("curious results" in the cores, yeah, thank you very much, I guess?), plans vs. how it was actually built differ, and photos and videos (more so if sub-potato quality) can be deceiving by their own very nature. Without being there and with the limited access we have (thankfully, I'd say), we know no better. If the scope of the exercise was strictly limited to discussing good/bad practices then by all means, I agree that having experts in those specific fields is the bee's knees, but over the span of 5 topics it simply unhinged from that premise and became a let's throw around hypotheses on the cause - including from structural engineers themselves - so the finger pointing now seems a bit uncalled for.

Dont know if it matters to anyone, or not, but if it does, I am 100% certain that Vasquez learned that the parking area had collapsed certainly after leaving the lobby and probably the property. Just by the words he used. If he saw the parking garage, he would had said that he saw it, not "understood" it. He also said that on the way out Gimena ran into a palm tree and got a knot on her head, so that doesn't sound like they were leaving via the parking garage.

And as for not believing that the other guy would leave that complex to check into a hotel, just because the power had been cut to the unit they were going to stay in, I suggest that you have never tried to sleep one single summer night in Miami with no AC, especially if you are used to cooler nights. Totally plausible. Ask for a night's refund the next day.

I also don't think that the camera was necessarily triggered by motion of the falling debris across the street, high up and in relative darkness, but by the seismic event of the first large pieces hitting the ground and swaying the camera, causing it to see relative motion of objects within the well lighted close field of view. I think I see some evidence of that in the ripple patterns in the pool as well. If the wind started the camera swaying, it would be recording all the time.

My guess would be 4000psi concrete in columns made in 1981.

Quote (Demented (Industrial)12 Jul 21 11:05
Crack, or exterior cable being run? If a crack, then this could very well explain why the penthouse does appear to be missing in the start of the collapse.

hochhaul (Industrial)12 Jul 21 11:50
I'm surprised nobody else has mentioned the phone conversation that Pablo Rodriguez had with his mother, Elena Blasser, hours before the collapse
)

If both of these prove to be true, it gives actual evidence to the falling penthouse balcony theory.

I once backed into a column in underground parking.
No visible damage to the column and no apparent damage to the car. The car was completely drive-able and you had to know where to look to see what visible damage existed. The plastic bumper cover popped back into shape. There was minor scuffing of a bright strip.
A few years later the car had to pass an extensive safety check and I had some expensive repairs of hidden damage to the rear underside.
Could a car have backed into a column with soft concrete and corroded rebar, seriously damaged the column, and still been drive-able?
I vote yes.

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

Quote (julootamu)

Three phase supplies are either provided in 460V or 208V. I'm sure each floor would be the same, as providing different phases on different floors would be impractical and confusing. In this case its apparently 208V. The good thing about 208V is that a connection from of the three wires of the 208V service to the neutral provides 120V single phase service. Two such connections can supply a standard 240V dryer/etc. While the 120V single phase powers lights/etc. There are special commercial appliances available at extra cost that are designed for three phase but I doubt they were required here.

On Floor 2, all three phases were distributed approximately equally, from a 3 phase 600A 208V sub-main breaker on that floor (this is where individual meters were). That is, 1/3 got phase A 208V, 1/3 got phase B 208V, and 1/3 got phase C 208V. Of course, the 120V went along for the ride.

For the remaining floors, the three phase was distributed as single phase over TWO floors, from a single location, in a similar manner. The sub-main was 800A.


spsalso

As speculation goes, we don’t even know that the CCTV footage was “triggered.” In fact, considering that angle doesn’t offer much from a security standpoint, why would it be?

This is a recording of a recording being played on a monitor. It’s just as likely that that’s where they cued it up to in their haste to make splash with the media.

The building had an Exterior Insulation Finishing System (EIFS) veneer, so cracks on the exterior are not necessarily structural concrete cracks. They may just be cracks in the EIFS. Also, the crack mentioned appears on the street facing (north side) of the structure, which did not collapse first.

Quote (Demented)

Crack, or exterior cable being run? If a crack, then this could very well explain why the penthouse does appear to be missing in the start of the collapse.

Collapse sending a shockwave down the columns until it transfers the load to the top of the M11.1 column, causing it to overweight to failure?

Edit: Original link to source where I found the image. Actual source and date unknown.

Pic is from Google Maps, it's actually on the north face of the building and it's most likely a cable. Navigating through the pictures from previous years, it's been there all along (I can't tell in the 2011 picture, but for sure from 2014 onwards).
Otoh if anyone wants to have a look at the joint between the wall enclosing the area accessible from the overhead and the penthouse roof on the actual collapse side, and if it may have been a weak point... I'm not sure anything can actually be inferred from the sorry state of the Google pictures (the only ones I've seen are from 2014/2015) and I'm not structural so it may just be the way it's supposed to be, but hopefully structural guys here can chime in?

Somehow this planter at ground zero of the collapse manages to remain mostly intact and not be covered in debris. I think it corroborates a slower settlement of the pool deck right in front of the initial building collapse area, and speaks to the completely vertical fall of this portion of the building. It fell completely within its footprint while the portion to the east fell towards the southwest.

To my Multi-Discipline Eyes, that looks like a bond beam/concrete filled CMU infill from top of a parpet wall as designed on drawings.

If columns can punch shear this patio deck, why the hell can't falling parapet or cantilever do punch shear from 13 stories up???

Did anybody find the missing parapet in the parking garage?
Maybe we will just have to wait and see where that landed.

So did floor 12 cantilever fail first, the second was penthouse cantilever? Would explain the diagonal tear out at stair tower based upon where this complete crack of cantilever and parapet is located.

Parapet is now in basement at same level as fallen patio, or same elevation as near base of punch sheared column. Does not have to be below to set up resonant frequency in patio deck, in my mind......

warrenslo where are you???

I certainly cannot discount that possibility. I think it dissapearance is still unexplained. It has not really been explained away either, as far as I know.

Quote (Hochhaul)

Yes, 1211. The apartment directly below the section of the penthouse suspected of having a roof collapse.

You may wish to make a correction to avoid future confusion. Elena Blasser and her mother lived in PH 11. Link

Of course the pile driving next door, and the effects of the Navy 3.9 explosion, as detected in Miami, all could have been contributing factors along with father time.

https://blogs.agu.org/tremblingearth/2011/05/05/sw...

Video link above showing high rise movement after 7.9 after shock for visual explanation.

Quote (Thermopile)

If columns can punch shear this patio deck, why the hell can't falling parapet or cantilever do punch shear from 13 stories up???

It most certainly can.

Interesting question, only because I have witnessed a kid in Miami on a job jump off the 6th floor thinking he could special forces swing into the floor below. He was instructed to drop to the floor below by his supervisor, so he did. Thankfully fall harnesses work, but the labor force in Miami is very suspect.

Could there have been a bag of roofing tools and/or rolls tied off to the new anchor points and hung off the side of the building?

Total speculation.

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

Quote (spsalso)

On Floor 2, all three phases were distributed approximately equally, from a 3 phase 600A 208V sub-main breaker on that floor (this is where individual meters were). That is, 1/3 got phase A 208V, 1/3 got phase B 208V, and 1/3 got phase C 208V. Of course, the 120V went along for the ride.

Perhaps I am being pedantic here but you need two phases and a neutral for each apartment to have 208/120v. Such as 1/3 get A phase, B phase and neutral, 1/3 get B phase, C phase and neutral and 1/3 get C phase, A phase and neutral.

[quote demented][/It most certainly can.

Interesting question, only because I have witnessed a kid in Miami on a job jump off the 6th floor thinking he could special forces swing into the floor below. He was instructed to drop to the floor below by his supervisor, so he did. Thankfully fall harnesses work, but the labor force in Miami is very suspect.

Could there have been a bag of roofing tools and/or rolls tied off to the new anchor points and hung off the side of the building?]

Definitely Plausible with suspect work force..........So the green bundle of roll roofing could have been say the 2500 lb test rig, and tied to roof anchor with rope across top of parapet to really load those cantilevers well?

Quote (ce3527)

Somehow this planter at ground zero of the collapse manages to remain mostly intact and not be covered in debris. I think it corroborates a slower settlement of the pool deck right in front of the initial building collapse area, and speaks to the completely vertical fall of this portion of the building. It fell completely within its footprint while the portion to the east fell towards the southwest.

To my tired eyes, that portion looks exactly like the view I believe we see from thr tiktok video, and why we do not see particular columns, beams, or fully discernable items from the location other than fallen rock looking structure, draining water pouring in from a similar flow path, and hanging debris.

*shrugs*



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

The green covering could still be seen on the post collapse photos on the un-collapsed portion.

CE3527,

Good catch, and there always is the possibility that the first collapse was a roof area above a condo with the green bundle sitting on top So the power flashes could have been an internal failure of roof slab we were seeing before the later events.

But it appears that bundle was sitting near if not on cantilever of 12th floor roof, and you can see where the flying buttress wall for the penthouse crashed down on the potential green bundle in that area

Quote (Nukeman948)

Perhaps I am being pedantic here but you need two phases and a neutral for each apartment to have 208/120v. Such as 1/3 get A phase, B phase and neutral, 1/3 get B phase, C phase and neutral and 1/3 get C phase, A phase and neutral.

Perhaps. But the power to each unit is called single phase.

Interestingly there has been two phase electricity, also. But since you need 4 wires to run two phase but only 3 wires to run 3 phase, I doubt it's in much use anywhere.


spsalso

And we know it was flat slab above condo picture sliding door windows, therefore no beam under where that green plastic is sitting other than of course the aluminum frame of the sliding glass door. So a bundle there is 'Suspect Labor' or “suspect Manager” error, or common place in American these days, unfortunately

I think the video was motion triggered.. because the original starts with a "no video" screen - https://www.youtube.com/watch?v=K6ea90YGGBg Also, they could have easily added another 10-20 seconds to this video and it still would have been small enough to email without having to do much work to it.

But how these get triggered is by percentage of movement.. so they won't pick up palm trees, etc, swinging in the breeze. They're meant to pick up movement of a person in the foreground, so anything smaller than about that size is unlikely to get caught. It probably triggered at this moment because the movement was finally big enough to look like a person. It seems like the trigger probably missed a second of the movement as it turned on too, which is why we see the roof already collapsing down when it first starts.

Also, PH-11 and 1211 are the same apartment btw. And the roof theory seems sort of unlikely because of how far that collapsed column is from the roof area. Something would have had to have fallen from the roof, moved over a few feet on the way down so it fell right above a column, and somehow damaged it so much that it's not easy to see in the tiktok video.

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?

My security cameras have sensitivity setting. They are at soffits of structure, and sensitivity is limiting range too. My front one sees street but is set to ignore that range and focus closer to front door area. However, significant movement at street could trigger them. Vertical motion downward would be more visible and much larger area of movement

Quote (spsalso)

Perhaps. But the power to each unit is called single phase.

Interestingly there has been two phase electricity, also. But since you need 4 wires to run two phase but only 3 wires to run 3 phase, I doubt it's in much use anywhere.

You can call it single phase if you want, but you need three wires to get dual voltages. American homes have dual voltages as well and have two phase wires and a center taped neutral. That's how it's done and it is the same with three phase systems.

Two phase power is still in very limited use, mostly for old elevator service in old buildings in cities like Philadelphia. My 1932 code book has a diagram that shows how to wire a two phase 5 wire transformer. ( see also Scott-t transformer connections for 3 phase to two phase 5 wire).

jbourne,

Things don’t just stop in their cold tracks where they land. There is multi-axis vectors involved, and of course bounce and roll effects. Drop a ball off roof and I bet it does not end up in same spot as it first impacted the ground.

spsalso states "Interestingly there has been two phase electricity, also. But since you need 4 wires to run two phase but only 3 wires to run 3 phase, I doubt it's in much use anywhere."

There is 3 phase supply wiring to the building (Wye or delta) . No 2 phase in this building (Theoretically possible but surely not here in this century. You are right that 2 phase non-existant in USA today) Depending on internal wiring connection/ transformers supplies one phase loads in the building. Some three phase power distributions have 4 wires (neutral as well as three hot conductors). I worked for an electric utility. All loads in building condos likely 1 phase. Only large motors (3 to 5 hp and above would run directly on 3 phase power.

Lots of flxibility to the end user but in this size building the utility supplies a 3 phase service which can be made to supply single phase appliances.

Has little to do with the why the structure collapsed. Need a better video of collapse for starters. Otherwise will take months.

Hello,

Several days ago someone posted a link to a YouTube video by an architecture professor (in Argentina?) that was very well done. He posted an updated video yesterday and I haven't seen it linked or discussed here yet so I thought I'd post the link:

https://youtu.be/c-1wwF_STiY

I don't speak Spanish but I turned on closed captioning and in the Options I chose to auto-generate captions in English. I was able to get the gist of what he was saying.

I'm not a structural engineer, rather I'm a Cybersecurity Engineer, but I'm finding the discussions here fascinating.

Cheers,
Tony

Thermopile, Good point. It also seems pretty clear that the pool deck closest to the building collapsed while the pool deck on the other side of the column stayed partially up.. or we'd be able to easily see column 28/M12.1. But it does seem like with the damage down there something very large would have had to of fallen to be the trigger.

Quote (julootamu)

Has little to do with the why the structure collapsed.

Nothing to do with the collapse, but the electrical discussion started when people questioned how some lights were still on in the video when the building had already fallen 20 feet. The bluish colored lights are most likely arc flashes from the feeder wires getting pulled out.

Quote (Thermopile)

warrenslo where are you???

This guy?

Quote (warrenslo - July 6)

Alan knows it was the roof anchors but cant prove it yet, boom:
Link

Quote (Allyn “Alan” (sic) Kilsheimer - July 12)

“We don’t know enough yet. This is in the infancy of this particular thing. And, all these armchair quarterbacks — both engineers and non-engineers — out there that have all these ideas about why this has happened, they don’t have any basis of fact for it,” Allyn Kilsheimer, founder and chief executive officer of KCE Structural Engineers, said in an interview Saturday.

“We’re basing everything we do on facts, and we don’t have any inkling right now on why this occurred,” he said. “Right now, I don’t know what caused it. I didn’t know what caused it the first night. I still don’t know what caused it now.”

Hired engineer: Still ‘no inkling’ to why Surfside building collapsed

Quote (jbourne8)

But how these get triggered is by percentage of movement.. so they won't pick up palm trees, etc, swinging in the breeze

My IP cam has a 0-100 sensitivity setting for the trigger.

You can also set how the triggered activity gets recorded. I can record up to 20 seconds *before* the detected movement (not yet flushed from camera memory by new data) if I set it as such.

Electrical folks - good info on the phases.

Could the units be split-single phase, or would this require an extra transformer on each floor?

The main answer I’m trying to get to is how many different phases - that is, 120 degree phases off the 480 system - left the electrical room on each floor, and in what combinations.

Was each floor balanced across all three phases? Was each floor given 2 of the 3 and the system balanced across all floors but not each floor? Or did each floor have a split-phase 120/240 and only one of the 480 phases was active for each floor?

Because it looks like some of the floors go out at the same time, leading me to think they shared a phase. Ultimately, if we knew which phases fed which units, it may be possible to positively identify the floors by which other floors they were sharing a phase with, based on when the lights went out.

What got me started on this was the light in an x10 unit being turned on during the collapse. I was hoping to compare that to which of the x10s were occupied at the time. Unfortunately, all of the upper ones were, so it’s no help. But maybe the electrical outage sequence could lead to pairing up two sets of lights and confirming they are floors 9 and 11 for example, as opposed to 8 and 10.

The more I look at the slab step from pool to patio level in the K-M 9.1-11.1 area, the more concerned I get. The construction details show a couple of bottom bars and a couple of top bars making a beam of sorts at these slab transitions. However, the pool level slab is basically hanging from the bottom of the 'beam' which means that it is really just relying on its own steel and concrete in tension for support. To complicate that, heavy planters are installed right on that edge in really the worst possible location.

Considering some of the other alarming things we have seen in the reinforcement steel, it is possible and maybe even likely that the pool slab was poured first and then the top half of the 'beam' and patio slabs were poured on top of the pool deck. This would pretty much eliminate any support along that edge. Also, although there are small beams along the K-M column lines, these are also stepped with the deck. Depending on how the steel was laid and how the slabs were poured, these beams may not provide much support.

My theory is that the pool level slab lost support midway between lines 9.1 and 11.1, probably right at the step-up. This overloaded M11.1 and L11.1 for certain, and probably also K11.1 to start. I am 90% certain that the stills from the garage entrance show that the planter that was on top of M11.1 punch sheared over the column and this caused the column to collapse. I think that the lower yellow part of the column is inside of the planter and the top part is broken and laying on top of the planter. The next bay to the north (M-N) does not have a patio level slab and appears clear of debris.

If, as I suspect, the failure was midspan, you would then have the patio slab hanging off the the 9.1 columns and likely attached with a few hook bars. While the moment load would be large, I don't think it would have been fatal. However, it is not hard to imagine the hook bars taking large chunks out of columns K, L, & M on the 9.1 line. The building might withstand one damaged column, but three in line on the outside line of the building would likely bring it down. Had everything been on the same level, the bars would have been continuous over the columns and this probably would not have been an issue.

There was also progressive failure of the slab from north to south, which from witness accounts probably happened before the 9.1 column line failure. However, none of this really mattered, once the slab failed between 9.1 and 11.1 the building was doomed. Similar column failures did not happen along column line I on the southeast side of the building because the slab was one level and dropped as a unit instead of being cantilevered and damaging the column as hook bars pulled out.

Potential Causes:

1) Design - While the design my have met all RCC codes at the time, the slab steps midway between column lines is less than ideal, especially with the planters added right on that step. Drainage for the exposed slabs appears to have been inadequate.

2) Modifications - It appears that planters were added over the years that may have made matters worse. These is a flat planter south of the original taller planters and the large square planters on line 11.1 appear to have been added as well. These contained palm trees for several years and added considerable weight.

3) Construction - Rebar placement does not appear to have been done according to plan and there are several disturbing pictures of atypical punch shear, evidence of very poor column/floor attachments, etc.

4) Maintenance - Allowing water infiltration for years was clearly an issue and needed to be dealt with more aggressively. It also appears that some of the work was not done properly and this all contributed. Not that one top bar was the difference, but I would not like to have to defend coring through it when methods exist for avoiding that issue.

Quote (LionelHutz (Electrical)12 Jul 21 13:04
I'm not understanding why a rebar in a column ending in a slab joint would be an issue?)

In this instance it is mostly just an indication of poor rebar installation. BUT a closer look seems to show the bar from the left passing behind the bar from the right and all may be OK.
IF it is two bars terminating in a gap, the problem becomes one of column capacity, particularly after 40 years.
Columns suppor axial load, and both concrete and steel shorten under compressive loads. Initially they share loads according to their ED ADD relative area and elasticity. Add the creep of concrete when under continuous loads for long periods and the concrete begins to transfer some of that load to the steel, which does not creep. The transfer from bar to bar is usually thru bond and concrete shear between the bars.
The gap would not allow that transfer.
In the perceived case of a gap, at a slab connection, either bar would have no development length beyond the gap, and therefore no stress development to provide anchorage and resist moments induced at the joint. In short, if all bars were 'gapped' there would be no stabilizing effect at the joint and the column would likely loose capacity.
EDIT ADD When a bar in compression MUST be aligned above and below the splice, mechanical couplers are used to maintain the alignment and contact between the bars spliced. That maintains the loads and passes that load to the bar below. The couplers come in several forms - some are fitted and fused in place by igniting a powder to melt and lock in place, some are crimped in place just like a butt connector in an automotive wire, and some thread the bars using a steep taper and short coupler threaded together, similar to pipe.

Garage image folks - if the contention that the building never left its footprint to the south is true, then all of the objects in the tiktok video may actually be the same objects visible in broad daylight after the collapse. Perhaps these could be mapped in terms of how they would appear to the tiktok user and we’d get a better perspective.

For example, are any of these objects visible?

Js5180, I think in that USA today garage video it looks like you can see the top of the pool slab. It looks something like this:


It's very hard to make out though, so I'm not sure that's correct. But if that's the case.. we wouldn't be able to see any of those objects. Since we can't clearly see column 28/M12.1 it's hard to say though. I think that white object on the ground might just be one of their planters too, not the missing column.

Quote (Spartan5 (Civil/Environmental) 12 Jul 21 17:47 Quote (Thermopile) warrenslo where are you??? This guy? Quote (warrenslo - July 6) Alan knows it was the roof anchors but cant prove it yet, boom: Link Quote (Allyn “Alan” (sic) Kilsheimer - July 12) “We don’t know enough yet. This is in the infancy of this particular thing. And, all these armchair quarterbacks — both engineers and non-engineers — out there that have all these ideas about why this has happened, they don’t have any basis of fact for it,” Allyn Kilsheimer, founder and chief executive officer of KCE Structural Engineers, said in an interview Saturday. “We’re basing everything we do on facts, and we don’t have any inkling right now on why this occurred,” he said. “Right now, I don’t know what caused it. I didn’t know what caused it the first night. I still don’t know what caused it now.” Hired engineer: Still ‘no inkling’ to why Surfside building collapsed)

I can understand that KCE wouldn't want to speculate at this point in the investigation but its not quite right to say that its too early to form a hypothesis. We have the original plans which are LOADED with red flags that strongly suggest the original design was flawed. A serious investigation of the failure begins, logically, with a careful analysis of the loads on the building and the structural capacity at each critical location based on the original design. You cannot assume that because the building stood for 40 years that the design was correct, whether or not it was done to code. If after this analysis, you don't find a flaw then you move on to other causal factors, including concrete and rebar deterioration, construction errors, additional loads added later, catastrophic loads immediately prior to the collapse, etc.

As far as this talk about various roof elements causing the collapse, I think most structural engineers, myself included, are not that interested in this discussion, maybe it triggered the collapse, or maybe not. What really concerns me is that Morabito inspected the building and did not really find anything that would make any engineer think that the building would collapse 3 years later. The worst damage he shows is to the pool area which stayed completely intact throughout the oollapse.

Ok, JBourne, that vertical bar in the gate, where the diagonal ornamental bars join, right of the “C” - from the camera’s point of view, where would that line fall on the pool deck in my picture?

It should be an exact line, and from that, maybe some of the other details match (or don’t match). But the line can be drawn exactly if you have a few known points, which we do. Every object in the Tiktok video can be placed within a triangle in the pool deck, and for one dimensional objects like the vertical gate bars, you can draw exact zones across the pool deck.

tmwaits1,

IMO, we only care about the trigger, in order to understand the design, construction, or maintenance issue it exploited, or in reality the combination of factors that led to the perfect storm. With this information, designers and code agencies can determine requirements that prevent tis tragedy from happening again. Collective brainstorming aids the process, but unfortunately it brings excess baggage too. If I am Alan, I want us to shut up on one hand, but on the other, I bet he has a groupie reading this forum.

Catch 22

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=325ca65d-6749-4a61-ba79-6

tmwaits1, I also find the roof discussions a bit boring with such a lack of evidence. Not to mention the building inspector being up on the roof 14 hours before collapse and not seeing any problems up there. They're almost as bad as the car discussions.

Js5180, I think if the pool deck were still standing, it'd be about here.. it's hard to place within the rubble though since you can't see it. I'm not sure if it's a diagonal cut either, seems like it could be straight and just sloping down in the direction of the V during the video.

jbourne8,

But the PE SI had thoroughly inspected the facility, and was managing current phase of work. So it appears he saw no issues that would lead to this being an emergency. You can not see hidden problems with mostly a vision analysis.

Thermopile, Yea, mostly it seems relevant that the roof was inspected because if anything was in danger of falling off the roof, it seems like he would have noticed. But he also only inspected the roof, and not the garage.. which is where the collapse started.

Teguci, Nice write up! That white line I drew where the slab looks collapsed in that garage video is also suspiciously close to where you suspect the failure occurred. The rest of the slab nearest to the building seems to be on the floor of the garage, and M12.1 seems like it might be already puncture sheered. It all lines up really well with your thoughts on it too. It's nice to see the deterioration theory clearly written up.. although, very scary too.

I was thinking more like this - forgive the hand drawing.

Basically, tracing rays from the camera, through each bar in the gate, and out to the pool deck. We have exact blueprints and dozens of fixed objects to use. I may be able to work on it later, but this is the idea:



Then you can compare objects in each zone of the pool deck with objects in the tilt ok and try to determine if any of them match up. I’m thinking that white planter box is a candidate.

jbourne8, So you can prove it started at bottom. I am impressed.

Why are you ignoring facts like the fully developed crack in the cantilever/parapet over the 12 th floor. I assume because we don’t need to worry about suspended slab problems, because you already know it was solely bottoms up?

What if the crack just appeared due to loads being placed on cantilever by roofer?

Actually it might have been just over sliding door line?

Thermopile, I can't prove anything? Pretty sure every single structural engineer in here has said that it started at the bottom, and I trust their judgement. They can feel free to correct me, but I'm pretty sure this is a fact now. That crack is on the opposite end of the building from the collapse, so I guess I don't see how it's relevant. Someone also suggested it was a cord or just a crack in the facade, which would match what MC said in the 2018 report too.. they had cracked stucco. A crack doesn't really prove much at all if you ask me.. this building had cracks all over. That hypothesis that Teguci posted is really worth reading over.

Js5180, Nothing in that photo lines up because it's underneath all of the rubble. Perhaps I should have drawn the line on the ground so it was easier to visualize instead of where the slab used to be.. but it's under the rubble in that pic. The planter is next to and behind column 28/M12.1 and something is clearly blocking the view to it.

Sorry if I was wrong about location of crack, as now I can see it is not in the area I thought it was. So irrelevant to collapse but serious maintenance issue. Look at crack on Memphis bridge tie girder, and how they reacted to that elevated crack.

Picture is opposite hand of area of interest. Perhaps, old eye-brain function. But theory still valid and remaining green tarp or bag is in right spot.

For what its worth, I've seen a 12" Dia concrete column taken out by a forklift (higher mass, but lower speed than a typical car). Photo from during the repairs. I'm skeptical of the car crash hypothesis in this instance, but there can be some plausibility to that.

And it is typically a point of local maximum moment for a column, if not the floor as well, so continuity through each member is normally highly desirable.

Quote (Js5180)

Electrical folks - good info on the phases.

I'll try to answer your questions but I have not seen the electrical drawings and it seems that spsalso has so I will use the info he posted and my real world experience.

The building probably had 480/277 service for things like fire pump, domestic water pumps and pool equipment. 277v could have been used for house lighting. Then they would need a large transformer to provide 120/208v three phase. This would be fed to sub panels throughout the building. The sub panels each fed two floors of apartments above the 2nd floor. The 2nd floor panel MAY have fed a service panel for house lighting and general use receptacles for all floors so you can't use a sequence of lighting outages to help determine how the building failed.

Each sub panel would feed an equal number of units with a two pole breaker giving 120/208 "split phase". The phases are 120 degrees apart instead of 180 degrees and that is why it is 208v and not 240v. You lose efficiency for loads like water heaters and ovens but save on needing more transformers.

You can never balance the loads completely because some units on the same phase may be unoccupied. The best you can do is feed the same number of units on each phase and monitor usage to see if you need to re-balance later. With 24 units being fed from each panel you would feed 8 of them from a two pole breaker on A and B phase, 8 from B and C phase and 8 from C and A phase. That gives you 208v for each and then add a neutral for the 120v circuits.

Kudos to Teguci for taking the time to throw some schematic analysis at the plaza-level slab deterioration theory. It's not as sensational as the roof-level theory that seems to continue to pervade the conversation, but certainly most plausible in my mind.

Where are the plumbing chases? I'm wondering if they were a failure node.
Fire water supply piping should exit out of the generator room and do a vertical run. The dryer vents, not sure what path they take, where they are.
I just wonder if that's a roof-basement weakness or path. Some fire-proofing was going to be added at each floor and not sure if there is concrete there.

Quote (Js5180)

Electrical folks - good info on the phases.

Could the units be split-single phase, or would this require an extra transformer on each floor?

The main answer I’m trying to get to is how many different phases - that is, 120 degree phases off the 480 system - left the electrical room on each floor, and in what combinations.

Most apartment panels in a 120/208V 3P4W system will have 2 hots and a neutral. These will get staggered in the meter bank, e.g. Meter 1 is L1L2+N, Meter 2 is L2L3+N, etc.

More importantly, though, is that the runouts (and sometimes the risers) from meter banks to apartment panels are very frequently run in flexible metallic conduit (FMC) in a drop ceiling, soffit, or other interstitial space. Unless someone can conclusively prove that all the apartment runouts were piped in EMT, you really can't, and shouldn't, read anything at all into the timing of the lights going out.

Quote (lucky555)

Fire water supply piping should exit out of the generator room and do a vertical run.

Yes. They exit the generator room and go through the parking level to the stairwells where they are protected and still accessible for testing and maintenance.

OK. Great, because I'm beginning to think it started with a transformer explosion.

NOT.

It's not unusual for a fire pump to have its own eletrical service seperate from the rest of the building. Generally overcurrent protection is not allowed upstream of a fire pump controller.

Teguci's post about the design/deterioration really explains every single video and fact perfectly. It seems like the slab he's describing is the one you can see laying on the garage floor in that tiktok video too. The north building also doesn't seem to have this same design flaw even though they were supposedly built with the same plans. You can see this section of their garage at 3:31 in this video - https://www.youtube.com/watch?v=arUOCTDRnCc

He never looks at M10.1, but on the left you can see M11.1, and M12.1 at the center of the screen. There is no beam connecting M10.1 to M11.1 in their garage, and no step in between them. Instead the step seems to be sitting on M10.1. Or perhaps there's a soffit or a drop ceiling covering it there? If not, it does make you wonder if they noticed the flaw in between the two buildings and then tried to fix it on the north one.

I think the curious thing MC noted was that the building slab actually did have a slope to it when he tested it in 2020, but in 2018 that was his best guess for why it was so deteriorated within the garage. It's brought up a bit in those board meeting notes in 2020, and it says that he was going to need to test the slope further. It makes sense that the design problem was actually much more complicated than that.

Quote (1503-44)

OK. Great, because I'm beginning to think it started with a transformer explosion.

What evidence do you have for that? The electrical riser diagram (page 83 of the big PDF) has the entire building on 208V 3 phase, unless I'm missing something, so there shouldn't be any transformer other than the main one beside the service entrance. That part of the building survived the collapse without much damage. The subsequent fires in that area might have come from that transformer vault, possibly, but that's secondary to the major collapse.

It was between column lines C and D, and between row 1 and 2. That's the far west segment of the northern exterior wall. Nothing I have seen points to a transformer explosion there, or anywhere else. It's a long way away from K–M on the 9.1 row.

Thermopile, You can see where it was taken from in this doc.. it's next to the planter and above M11.1 - https://s3.documentcloud.org/documents/20985354/20...

You can also see a lot of deterioration on that planter above M11.1 (the one on the right in the pic) if you zoom into the pic.

Hi! I just joined, and wanted to share what I saw about the electrical system in the plans. I'm not an expert by any means though.

It looks like all the electric wires come up from one place, then go horizontal through the even numbered floors. The plans have a meter room on some floors, and in pictures you can see what looks like 12 conduits coming from the shear wall where the meter room should be, on the even floors as the plans predict. So the x10s and x11s should have lost power as soon as the slab broke from the shear wall.

Page 58


Page 83

Quote (zebraso (Mechanical)12 Jul 21 08:03)

Still can't read the license plate

Can't even read the sign on the gate, and we know what that says...

SF Charlie
Eng-Tips.com Forum Policies

Quote (jbourne8 (Computer)12 Jul 21 08:48)

what else could possibly cause this sort of destruction down there

Yes! That's the $300M question.

Sorry, I still think the Patio Table looks an awful like the ventilator from the garage roof

SF Charlie
Eng-Tips.com Forum Policies

Sorry, I picked wrong diagram. I mean M-11.1 for core sample A.

I give up, I am out. I can not keep facts straight when looking at pictures....

Old Age Sucks!

Please don't everybody clap at once.............

Quote (SFCharlie (Computer))

Can't even read the sign on the gate, and we know what that says...

That's an excellent point. It's a level of detail on a small level that is known from other sources (not the frame from tictok rendering that I have seen). You can infer something from any attempt to enhance detail using that as a reference.

Probably my last post on this too Thermopile, I'm pretty satisfied with Teguci's theory.

Here's a rough drawing of what I think the slab on the ground in the tiktok video looked like exactly, and where it was before the collapse if it fell straight down. It all seems to line up too well with what he suggested. I guess this means that missing column must be hiding from view under the planter.. makes the most sense really. I left out all of the areas that are outside of the camera view too.

Softee - thanks, very helpful. Can you link to that? I think I have the reno plans but not that one.

I notice the closets are on 2-5-8-11, while the riser diagram shows 2-3-5-7-9-11, and I don’t see anything covering the PH. Not sure why they would be different.

Do you see anything that indicates different phases?

Quote (Thermopile (Aerospace))

I give up, I am out. I can not keep facts straight when looking at pictures....

You're just overloaded right now. To be expected. Take a well deserved deep breath and come back with a fresh perspective. Everyone's been there.

Teguci - I believe that slab drop is 1'-11", not 11". It is incorrectly noted as 11" on the Morabito report plans, but the plaza and entry slab elevations are noted on the original plans as 10'-10" and 12'-9", respectfully.

Regardless of that discrepancy, I think your hypothesis pretty much aligns with what I was thinking yesterday:

Quote (bones206)

The angle of the planters (what I believe are the planters) leads me to conclude the slab failed around the 1'-11" elevation drop at the edge of the long planter. The slab would have hinged along grid 11.1 and dropped to the shape of a ramp. That would explain why some of the planters look high up in the photo. Then maybe column M11.1 buckled and fell to the right after the initial slab collapse.

Quote (bones206)

The thing that's nagging in my mind is the column on the left (M10) is supporting the building and the column on the right (M11.1) is only supporting plaza slab. But since they are connection by a beam, if the column on the right (M11.1) collapsed for some reason, the falling slab would cause the beam to rotate clockwise and put a huge bending moment on the left column (M10). That's a plausible trigger for the subsequent building collapse.

However, my thinking evolved after it came to light that the surface level parking area along Collins Ave may have collapsed virtually at the same time as the planter area around column M11.1:

Quote (bones206)

If that account is true, it would indicate a larger area of initial collapse of the plaza slab, to include the area where cars are parked. As opposed to a more localized collapse in the vicinity of the planters/column M11.1.

So if we accept the timing of the surface parking collapse and we take into account the many punching shear failures that were the first thing everyone noticed when the dust settled, do you agree with the logic that the initial plaza slab collapse was more likely a much more widespread event? I believe that the failure of the planter area and beams connected to M10 eventually triggered the building collapse, but I'm not so sure anymore that the plaza slab failure started there. It seems to me more likely that it was a widespread progressive collapse of the entire plaza slab, that may have slowly accelerated over several hours based on the timing of witness accounts of creaking/cracking noises. Putting the timing of the tik tok video together with the timing of the Vazquez/Accardi elevator ride, it would appear the planter area and surface parking area collapsed about at the same time. Since those two areas are on opposing sides of the lobby, it follows that the plaza slab collapse was widespread and wrapped around the building. This is consistent with the aerial images that show the slab sheared around the perimeter of the basement. Initially it was hard to say whether this was a precursor or a symptom of the building crashing down onto the slab, but I'm leaning towards the precursor theory.

Does this logic make sense?

For larger services, three phase is more economical than single phase.
I don't know the current break point but guess around 400 Amps plus for the service to go three phase.
The breakers are installed onto bus bar extensions.
From top to bottom in a panel the bus bar extension phasing is:
A phase.
B Phase.
C Phase.
A phase.
B Phase.
C Phase.
A phase.
B Phase.
C Phase.
repeat.
The top breakers are A + B phase.
The next breakers are C + A phase.
The next breaker spots are B + C phase.
In Canada AC90 is often used for feeders to apartments. Armoured Cable, 90 degrees Celsius rated.
The labour cost is often the lowest.
480/277 Volts for large motors? Again an economic concern.
First choice is all 120/208 Volts.
If the addition of the large motor loads in the design phase requires a larger transformer, then the option of a larger transformer may be compared with the option of a second 480/277 volt transformer.
Another factor may be the use of motors above 200 HP.
A rule of thumb says that it is desirable that the motor HP not exceed the voltage.
The rule may be broken on both economic grounds and on voltage dip when a large motor starts.
It depends.
Most designers will run one 250 HP motor on a large 120/208 Volt service.
A 400 HP chiller motor will have serious consideration of a higher voltage.
Four wire, 120/240 Volt delta? Forget it. Too many problems for large single phase loads.
Such as: the transformer bank capacity is reduced by 1/3.
For a given single phase 100 KVA load:
One phase will have 50 KVA at unity power factor.
One phase will have 50 KVA at 50% lagging power factor.
One phase will have 50 KVA at 50% leading power factor.
Wait! That's a total of 150 KVA for a 100 KVA load.
That is correct.
I told you that the four wire delta connection was problematic for large single phase loads.


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

Quote (jbourne8)

Teguci's post about the design/deterioration really explains every single video and fact perfectly. It seems like the slab he's describing is the one you can see laying on the garage floor in that tiktok video too. The north building also doesn't seem to have this same design flaw even though they were supposedly built with the same plans. You can see this section of their garage at 3:31 in this video - https://www.youtube.com/watch?v=arUOCTDRnCc

He never looks at M10.1, but on the left you can see M11.1, and M12.1 at the center of the screen. There is no beam connecting M10.1 to M11.1 in their garage, and no step in between them. Instead the step seems to be sitting on M10.1. Or perhaps there's a soffit or a drop ceiling covering it there? If not, it does make you wonder if they noticed the flaw in between the two buildings and then tried to fix it on the north one.

I think the curious thing MC noted was that the building slab actually did have a slope to it when he tested it in 2020, but in 2018 that was his best guess for why it was so deteriorated within the garage. It's brought up a bit in those board meeting notes in 2020, and it says that he was going to need to test the slope further. It makes sense that the design problem was actually much more complicated than that.

If I am not mistaken, the slope of the deck was such that water accumulated in that particular area. Not the entire pool deck draining towards it, but a substantial bit of the pool deck that was not flowing towards a drain and getting under the waterproofing through faults. This section, located under pavers and planters, directly ahead of the main entrance ramp, was in need of complete removal and replacement. There were also signs of failed epoxy repairs of cracks of the entire slab at that exact location.

Page 9 of the original structural report lays it all out for us.

Florida rainy season just started. 2.88" of rain in an area in 3 days collecting on a 0 years left slab. Unfortunate. Some simple shoring probably could have prevented this, but alas, that would have blocked the parking entrance and they needed the towns permission for off-site parking.





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

*shrugs*



It doesn't take a rocket surgeon to put 2 and 2 together, or does it?

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

Is it just me or does it look like a roof anchor crashed through the wall in this picture?

It seems like someone desperately wants to get this roof anchor narrative to take hold. It’s the flavor the of the week for those who have just joined in the last few days or so.

Does anybody know the timestamp in the re-occurring tiktok screenshot that appears to show a round object on the ground just below and to the right of the "C" on the vehicle gate? (aka the 'table'/'fan/'hvac unit'/'truck'/'portal to another dimension'. I have not been able to produce a similar view and I am wondering if it may in fact be a chance compression artifact.

For what is is worth to anybody, these are the images I have been referencing/processing during my reading:

Entryway Frame 259 Raw:


Entryway Frame 259 Deep:


Entryway Frame 274 Raw:


Entryway Frame 274 Deep:


Entryway Frame 291 Raw:


Entryway Frame 291 Deep:


and maybe I'm blind, but I'm not seeing anything that might resemble objects "from the roof". Rolls of tar paper etc...


EDIT: "hi-res" links:
1: Entryway Frame 259 Raw
2: Entryway Frame 259 Deep
3: Entryway Frame 274 Raw
4: Entryway Frame 274 Deep
5: Entryway Frame 291 Raw
6: Entryway Frame 291 Deep


Thanks.

Quote (Maud)

If you drive right past a fresh pile of broken concrete in your garage, and then the building falls down, you might think to bring it up.

You might even decide to gather your valuables and go sleep in a hotel...

New article on the analysis going on at the North tower.
Link


Notice how specific they were about the concrete drilling and refilling... Wonder why they are being so detailed specifically on this in the article?

Quote:

“We have scanned parts of the slab and some columns to locate reinforcing steel,” Kilsheimer said. “And then we have dripped some concrete core samples in the slabs, avoiding the reinforcing steel where we could. The holes will all be cleaned out and filled in with 8,000 PSI concrete before we leave today.”

Small world... a note from the STI... I'd signed up for a webinar on yield line analysis... but, now postponed.

"STI’s technical consultant and presenter of the webinar, Mustafa Mahamid, PhD, PE, is currently on site at the Champlain Towers South building collapse in Florida. He is assisting in the evaluation and recovery efforts there, and this effort will take him beyond July 14th. Our hearts go out to all those who lost their lives or loved ones in this disaster and to all the volunteers who are continuing to work in difficult conditions.

We appreciate your patience as we work to find a new date for the webinar. You will be notified as soon as possible of the rescheduled date. If the new date does not work for your schedule, we will offer a refund. If you have questions, please email us at hssinfo@steeltubeinstitute.org."

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

-Dik

I think your deleted post was right on the mark... sorry for snooping.

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

-Dik

ah ah , finally a documented attempt to examine the sub surface geology . If theres anything untoward down there , all the structural theorizing goes outta the window

Electronbelt - that just means the HVAC unit got run over by a car backing away from a column. Ha!

Quote (Keith_1)

Even IFF a car took out a column, there is so much redundancy built into a structure that it is a non-event.

How long will the garage ceiling or visitor parking deck stay in place after a column is removed, by a car or other event? Please provide your answer in 'seconds'.

Quote (miningman)

ah ah , finally a documented attempt to examine the sub surface geology . If theres anything untoward down there , all the structural theorizing goes outta the window

Link?
Edit: nvm. I see it now.

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

Until there is more information... I would lean away from the vehicle and the HVAC impact... even if the iniator... there's something much worse in play... even with the Twin Towers... the impact was a tad greater... was the fire and the damage to the fireproofing that did them in.

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

-Dik

Quote (waross)

The top breakers are A + B phase.
The next breakers are C + A phase.
The next breaker spots are B + A phase.

Excellent information is this post even though we learned this building was only 208/120, however the third breaker in your example would be B + C phase, then it repeats.

"Edited to add about the common practice, at the time, of using beach sand to mix the concrete which the beach sand would have salt in it which would corrode the columns from the inside out. It was built to fail."

I found this in a YouTube comment. Is this true? If so, it is sickening.

Quote (NOLAscience)

"Edited to add about the common practice, at the time, of using beach sand to mix the concrete which the beach sand would have salt in it which would corrode the columns from the inside out. It was built to fail."

I found this in a YouTube comment. Is this true? If so, it is sickening.

I last witnessed this with my own two eyes at a concrete pouring for for a high rise in Miami in 2019. Beach sand and fire hydrant water used to bulk up the short mixture on the ground floor slab. Spray galvanized SEB's inserted as well, randomly mixed in with the hot dip, along with out of code nelson studs welded on poorly.



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

Quote (jbourne)

someone posted info on where exactly Eric Zion lived in NYC,

No one posted "where exactly Eric Zion lived in NYC". The point was just that he may have been driving in from NYC. We don't know that yet, but maybe someone will find out where he was coming from. No one is advocating stalking and harassing this person. BUT, I know that investigators, and perhaps even police detectives, sometimes read this forum for ideas on what is possible. So stating an idea for investigation here means that someone might look into it.

Quote (jbourne8)

The reason why there are so many different disciplines in here is actually to make it easier for the structural engineers.

It's also a difference in interest. I think it's good for all disciplines to participate. Many from mechanical and IT have helped explain what would be expected with a building of this vintage, etc.

Quote (bones206)

I believe that slab drop is 1'-11", not 11".

There are 2 versions of this drawing. One undated version shows the 30" drop and the other undated drawing shows 18". The pictures seem to scale to the 18" version and the North tower also show an 18" step (maybe the earlier version was to provide for putting a proper slope on a plaza deck - the plaza drain plan indicates slope lines).

Quote (bones206)

However, my thinking evolved after it came to light that the surface level parking area along Collins Ave may have collapsed virtually at the same time as the planter area around column M11.1:

Eyewitness from room 111 reported that there was enough time between a loud crash and the observation of the plaza slab failing and then enough time from the plaza collapse to the building collapse for her family to escape. Punching shear is usually instantaneous, so the load crash would seem to be from an earlier trigger event. Further, I haven't been able to find an explanation why punching shear would occur at night without some other preceding event. Do you have any ideas for other triggering events? I do believe that the plaza failure, once initiated, happened like a quick wave radiating from the planter failure.

I think the final building failure occurred at K/10 when the weight of the failed plaza slab was applied to the "beam A" which then applied moment to the building column. Not entirely sure why there was a pause , but I'm glad the family from 111 was able to escape due to it.

Quote (emtv)

I for one don't care where any of these parked their cars, but I find that knowing about it is no different than knowing where any of the other residents were as they observed/heard the various events unfold.

Exactly!

Quote (Teguci)

Further, I haven't been able to find an explanation why punching shear would occur at night without some other preceding event. Do you have any ideas for other triggering events

Weather and a flooded deck. Overweighting the damaged slabs with water, especially when it rained just a little bit more that night, could very easily punch shear at random with no other initiating factor.

Pretty sure with a cracking overweighted slab, we'd here banging and popping noises similar to construction noises as the slab cracks, stretches, and shears the rebar.

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

Quote (1503-44)

And as for not believing that the other guy would leave that complex to check into a hotel, just because the power had been cut to the unit they were going to stay in, I suggest that you have never tried to sleep one single summer night in Miami with no AC, especially if you are used to cooler nights. Totally plausible. Ask for a night's refund the next day.

I've spent many post-hurricane nights on the Gulf Coast in a house without power. We have never gone to a hotel.

His mother owned condo, so there would not be "a nigtht's refund".

What is suspicious about the sudden hotel stay is the following:
He stated that he had just returned from a trip/travel with his wife. What did he need? Presumably he had his toothbrush and could hand-wash his skivvies if they all needed laundering. He spent a lot of time (1 hour) trying to get the power on (or was he gathering valuables?) and more time (30-40 minutes) getting other necessities after midnight. Most people would rather be showering and getting some rest in the hotel that they paid for.

As speculation goes, I do think that the people in the garage angle is a bit more plausible than the roof falling off angle.

Quote (Spartan5)

As speculation goes, we don’t even know that the CCTV footage was “triggered.” In fact, considering that angle doesn’t offer much from a security standpoint, why would it be?

I think that security camera has that view to get a view of the pool area, in case of excessive people in the pool (an unauthorized party) or in the case of a drowning. Maybe someone with knowledge of condo security cameras will have more info.

Quote (spalso)

On Floor 2, all three phases were dis

tributed approximately equally, from a 3 phase 600A 208V sub-main breaker on that floor (this is where individual meters were). That is, 1/3 got phase A 208V, 1/3 got phase B 208V, and 1/3 got phase C 208V. Of course, the 120V went along for the ride.

Aren't those Electricals so cute with their talk of phases, breakers, and neutrals?

Quote (NOLAscience )

I think that security camera has that view to get a view of the pool area, in case of excessive people in the pool (an unauthorized party) or in the case of a drowning. Maybe someone with knowledge of condo security cameras will have more info.

That sounds feasible. In my limited experience with CCTV, you can use a mask to exclude the areas where you don’t want movement to trigger the camera.

Notice that bush waving around in the foreground to the left. If this was a motion trigger, the bush would have likely triggered it. If it was a mask and it was activity in the pool they wanted as a trigger, they would have masked everything but the pool.

It’s weird to me that the footage faded in from the “no video” screen. Go frame by frame from the beginning to see it. If it were a constrained clip of some sort, starting with a trigger, wouldn’t it start with a static screen and a play button, or after being selected from a catalog of clips?

Demented, The deck seems like it was actually sloped from the tests that he did and those 2020 board meeting notes btw.. it said that he needed to do more testing to confirm though, and I couldn't find any info on those further tests.

NOLAscience, I'm sorry, but your insistence that this is a good place to investigate victims is the main reason I'm leaving this thread. It's sick.. let them have their privacy. I'm sure the cops are going to ignore every single one of your posts about Eric because they're all so misguided. And saying we need more information on where they were parked so we understand their statements is totally incorrect, we know that no one could have entered the garage without seeing the rubble pile. Digging for that info is just a gross attempt to place blame on someone more specific, to gain some traction to these insane theories that someone maliciously killed over 100 people and then waltzed off to a hotel for the night. And if you manage to get a specific person into a few lay people's heads that are reading these threads.. they can run away with the info and get crazy with it. It's happened time and time again with internet "web sleuthing."

I want no part at all in a forum that thinks it's okay to witch hunt any of these people. I honestly thought this was a group of professionals that wanted to discuss the building, but clearly some of you are not. I'm out.

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

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

is this some kind of Rorschach test? I see a huge black yellow jacket, with it's head center left, and it's stinger pointing down center. What do you see?

SF Charlie
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Quote (jbourne8)

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?

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.

Quote (jbourne8 (Computer)12 Jul 21 18:46)

It's very hard to make out though, so I'm not sure that's correct.

How is it possible to see "sky" when I'm looking down into the garage?

SF Charlie
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Good catch Nukeman948, thanks. Correction made.

Quote:

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?

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

Quote (miningman (Mining)13 Jul 21 00:25 ah ah , finally a documented attempt to examine the sub surface geology . If theres anything untoward down there , all the structural theorizing goes outta the window)

One thing you can see looking through the original plans is that the designer changed the foundation design from closely spaced precast concrete piles (PC) with a capacity of 50 tons each to a pressure injected footing (PIF) with a theoretical capacity of 150 tons each. This was clearly done to reduce cost as it allowed 2/3 of the piles to be removed. The revised layout with significantly greater spacing is shown in the drawings but the change doesn’t appear to have been incorporated correctly into the foundation design as there are some missing details.

Okay, what about the giant crack in the foundation slab between the ramp and M10 column? I understand that the ramp at the bottom sits on a beam between the two pilings / columns next to the ramp. Why is this slab cracked? It's a giant crack along the ground. You can see it in the video. It's about 50% between the two columns. Could there be a settling issue of the x10 columns? Why is the crack there and not between x10 / x11?

Perhaps there is a foundation issue? You have water seeping into the foundation in this region. This region is the region that failed the building. This spot seems to be where the trigger and cause will be found right?

If it's roof slab failure, then the roof hitting the pool deck just above here is the trigger, but foundation issues could also be an issue. Soil underneath this area could be a problem. How can you get such a crack on a foundation slab? Surely that thing is thick as and is resting on the pilings right?

Quote (NOLAscience)

No one posted "where exactly Eric Zion lived in NYC". The point was just that he may have been driving in from NYC. We don't know that yet, but maybe someone will find out where he was coming from. No one is advocating stalking and harassing this person. BUT, I know that investigators, and perhaps even police detectives, sometimes read this forum for ideas on what is possible. So stating an idea for investigation here means that someone might look into it.

The actual address was surely posted earlier, it may have been removed out since many people commented that it wasn't appropriate. The original posted actually live to street address etc. in NYC.

Quote (NOLAscience)

Aren't those Electricals so cute with their talk of phases, breakers, and neutrals?

They are actually providing some good information to correct some misinformation that's been given. Although I'm not sure exactly what difference the electrical discussion makes because it certainly wasn't the cause of the collapse.

What I am hoping, as a long shot, is that some combination of electrical arcing or lights being on or off can positively identify a floor or room in the collapse video at a specific time. If that happened, then we can tell whether the penthouse is present in the falling stack at or near its original height, or if it has compressed ahead of the floors below it.

Regardless of where else there was instability, collapsed slab, etc., a roof collapse of any kind could easily be the final trigger. That’s why I see the electrical discussion as relevant.

https://www.eng-tips.com/viewthread.cfm?qid=485223

Quote (jbourne8)

One wonders why you are so touchy about this. I am not alone in saying that Zion's story doesn't ring true. This does not mean that it is NOT true; it just means that there is much about it that should be investigated.

NOLAscience is just touchy because an Electrical pointed out that he had misquoted and mis-cited.

And so he decided to swipe at that very Electrical, ever so gently.


spsalso

Quote (SFCharlie (Computer))

I see a huge black yellow jacket, with it's head center left, and it's stinger pointing down center.

I'm having trouble seeing that within the context of the whole.

PLEASE STOP POSTING IN THIS PART 5 PLEASE
Please allow me to move the discussion to:
Miami Beach, Champlain Towers South apartment building collapse, Part 06
Thank-you.
Someone Please close this post to new postings, or message me how to do this, Thanks.

SF Charlie
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NOLAscience

I think it would be easier to calculate the energy transferred into to the car.

Try the red flag routine.
Click on Report at the lower right hand side of a post.
Send a message something like this:

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

Quote (spalso)

NOLAscience is just touchy because an Electrical pointed out that he had misquoted and mis-cited.

And so he decided to swipe at that very Electrical, ever so gently.

Not at all. I was just trying to make a little joke because the Electricals were having a side convo that kept coming up and coming up, and no one else was interacting with it.

I am a bit confused by the closure of the top of the Dade County courthouse building's top section , due to structural issues, but not closure of the bottom section. If the top section fails, how is one to assume the bottom section will not also fail? Is it possible they are just taking advantage of the overall fear factor to sneak in some architectural improvements under the guise of a structural deficiency?

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

I've RF'd this thread twice in the last two days to no avail

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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