you should add the previous links...

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

-Dik

An update on NIST’s progress to date. Includes a description of how they are documenting and collecting things, many pictures of the debris they have collected (alas, no AC), and some decent quality video showing the collapsed area. Looks like they are relying heavily on LIDAR and RFID tags, and conducting preliminary analysis using Ultrasonic Pulse Velocity (UPV).

https://www.nist.gov/news-events/news/2021/07/upda...

Copied over from 06.

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

Quote (bones206)

So the logic I am inferring from this sequence is that the collapse in the garage documented by the tik tok video could not have PRECEEDED the collapse of the surface parking area near the lobby, or they certainly would have noticed it before getting on the elevator.

Quote (mechinnc)

So where does the few minutes between patio collapse and building collapse fit in with what this crew saw? Presumably the garage collapse as seen in the tic tok vid had not happened yet while they were in the garage.

The timeline and 911 call timestamps are helpful in understanding what we currently know about this. Nicolas Vazquez's statements are difficult to evaluate by someone who does not speak Spanish and are subject to future clarification. ​

This is my understanding. Everything was happening very fast at that moment. Adriana Sarmiento's TikTok video starts after the Vazquezes got out of the garage. So her video is showing us what the garage entrance looked like right after the deck collapsed. By that time, the Vazquezes were up in the lobby with the Nirs.

• <1:15 am: Vazquez/Accardi drive back from dinner, park in the garage, walk to the elevator, hear a weird cracking sound, get on the elevator
• ~1:15 am: Deck collapse, witnessed from the lobby by Sara Nir from 111 and Shamoka Furman, security guard
• 1:16:27 am 911: "A big explosion" "earthquake." This call may be from Shamoka Furman
• <1:16:39: fire alarm directs elevator to lobby
• 1:16:39 am 911: Central Alarm Control calls in fire alarm.
• >1:16:39: Vazquez/Accardi exit elevator into smokey/dusty lobby, hear car alarms, see "sunken cars", and run out of the building with the Nirs just before the building collapses. In one interview, Vazquez said their entire experience occurred in less than five minutes. Sara Nir said that the building collapse just as they crossed Collins.
• 1:17:49 am 911: "earthquake" "the garage" "something underground... everything exploded down." *May also be Shamoka Furman
• 1:18 am: Adriana Sarmiento begins to video the rubble seen in the garage entrance.
• 1:22 am: Building collapses.

What I am still baffled by is what Sara Nir heard at 1:10 am. She said it sounds like a wall collapsing. All three Nirs said in multiple interviews there were three collapses preceded by the knocking sounds (which Chani Nir says were already happening at 11:00 pm):

• 1:10 am: Sara Nir hears what sounds like a wall collapsing
• 1:15 am: Sara Nir and Shamoka Furman witness the deck collapse
• 1:22 am: All witness the building collapse

Sara Nir, 111, heard the first crash at 1:14 am.

Quote (Washington Post)

The first thing she noticed was the knocking.
Then came a crash so loud, Sara Nir wondered whether a wall had come down somewhere in Champlain Towers South. And the second crash minutes after, in the lobby, where she witnessed the collapse of the car park.
Startled and up later than usual after an event, she put down her phone at 1:14 a.m. and made the short walk to the security guard in the lobby. The guard mentioned hearing the strange noises, too, but was unsure what to make of them.

Nir was still standing at the desk when a metallic boom reverberated across the building’s 12 floors.

Through the lobby’s wall of windows, Nir saw cars jutting out of the ground, some standing nearly upright, and the pool deck caved in. An earthquake, she thought, dashing back toward Unit 111, toward her kids.

This all correlates well with a collapse originating by the pool, and progressing toward the building.

The crash sounded above her because it was transmitted by the structural elements of the building around her. To me, it’s much more likely that that slab collapsing would sound like something above her than would something happening 12 floors up.

If we entertain the idea that the penthouse collapsed at 1:10, why would it be that no one on floors 12->11->10… were freaked out by it and called 911 and/or boogied on out of there? Especially if it was supposedly heard so clearly on the first floor?

In her first interview, she makes no mention of a noise like a wall collapse; describing the sounds as “construction knocks” or “renovation noises.”

https://collive.com/mother-escaped-with-children-r...

MaudSTL - nice job on the timeline, lines up with the fragments that have been reported. The overall 7 minute timeline for a concrete building to come down continues to be astonishing and I still don't understand the fire alarm. I suspect failures in the garage with the circuits to the devices coming apart sent a signal to the monitoring company, but there isn't any evidence the alarm ever sounded in the building. If it had, 6 minutes pre-collapse would have been plenty of time to wake people up and get them out.

There does seem to be a conflict between Nir reporting a loud noise at 1:10 and Vazquez/Acardi entering the garage at 1:15. They'd essentially be driving directly under the Nir apartment so it's difficult to see how any significant failures occurred 5 minutes before they entered the garage. It could be the Nir's were hearing the beginning of the punch through failures of the garage deck which may not have been as noticeable early on depending on where you were in the garage.

Spartan5, I enjoyed the NIST link. Hey looks like compression testing of core samples is old school now days with UPV. They have come a long way in Surveying since my college days walking all over campus with Optical Transit and Stick Man....

Edit: and a tape measure, plumb bob, etc.........

Quote (MaudSTL)

Don't forget poor Cassondra Stratton statement about the pool collapsing and the building shaking. She was at the unit 410.

"Mike Stratton awoke to the sound of his cellphone ringing. It was his wife, Cassie Stratton, on the other end, speaking frantically about their condo building shaking. She told him she saw a sinkhole where the pool out her window used to be. he heard a horrible scream and then the line went dead"

Here's some new info, so far as I can tell.

In reviewing some stories in Engineering News-Record, I found two pieces of information that may not have been previously discussed.

1. Jose Santini, a businessperson with a company that sells hurricane shutters, commented on an ENR article entitled, "Engineers Try to Fathom Factors Leading to Deadly Champlain Towers Collapse." In his comments, Mr. Santini states that at least two of the apartments in the part of the building that collapsed had 3" topping and tile added to about 2500 sf apiece. He did not name the two unit numbers, but did say he has photos available, and expressed his concern that this may have helped create an overload situation in a building with known subsidence. If anyone is a subscriber to ENR, you may wish to invite Mr. Santini to join this discussion and upload his photos.
2. Along with the roofer working on anchors and more, T-Mobile's contractor was also up on the roof doing antenna upgrade work on a permit issued 4/30/21. The upgrade work is not further described.

Quote (CE3527 (Civil/Environmental)16 Jul 21 19:44)

I'm still thinking no on the slab on grade removal,

I did not mean that I thought that they should excavate below the slab, I just thought it looked like they were doing that. Later in the day it looks as if they have sawn a hole in the slab and drained out a lot of the water.
First, they say they want a clean deck to show that there are no bodies left to be found.
Second, they may want to look at the pilings, I don't know.
Third, all concrete needs to be remove eventually to do whatever they will do with the property.

SF Charlie
Eng-Tips.com Forum Policies

Quote (Paul Austin)

Don't forget poor Cassondra Stratton statement about the pool collapsing and the building shaking. She was at the unit 410

I am working on an updated timeline that includes Ms. Stratton's call as well as Eric and Tamar Zion's activities. I didn't include them in the bullet list because we have no timestamps, and can't be exactly sure where they fit in.

I am guessing the Stratton call initiates somewhere around the 1:18-1:19 minute mark. From the statement by her sister, it sounds like the deck collapse had already taken place, and the mortally wounded building was shaking and struggling to find a new equilibrium.

We also know from what Adriana Stratton experienced at the garage entrance that many people woke up and ran to their balconies to see what was going on. The poor people Adriana saw on their balconies at 1:18 were only there for four minutes.

Quote (MaudSTL)

Thank you. I believe Ms. Stratton called her husband more or less at the same time Ileana Montegau from apt 611 started running towards the stairs and the Ringcam from 711 started recording.

Quote (CE3527)

but there isn't any evidence the alarm ever sounded in the building

Apparently the fire alarm worked in the surviving part of the building, but only after the rest of the building had already collapsed. I have seen articles where Esther Gorfinkel, who lived in the surviving part of the building, said she heard the alarm. But they were never specific as to when she heard the alarm. This piece, describing what happened to Alfredo and Marian Lopez after both the deck and the building collapsed, says, "The lights cut out and the emergency alarm came on, warning the residents of Champlain Towers South to evacuate."

Quote (MaudSTL)

Here's some new info, so far as I can tell.

In reviewing some stories in Engineering News-Record, I found two pieces of information that may not have been previously discussed.

Jose Santini, a businessperson with a company that sells hurricane shutters, commented on an ENR article entitled, "Engineers Try to Fathom Factors Leading to Deadly Champlain Towers Collapse." In his comments, Mr. Santini states that at least two of the apartments in the part of the building that collapsed had 3" topping and tile added to about 2500 sf apiece. He did not name the two unit numbers, but did say he has photos available, and expressed his concern that this may have helped create an overload situation in a building with known subsidence. If anyone is a subscriber to ENR, you may wish to invite Mr. Santini to join this discussion and upload his photos.
Along with the roofer working on anchors and more, T-Mobile's contractor was also up on the roof doing antenna upgrade work on a permit issued 4/30/21. The upgrade work is not further described.

Unit 1008 and 211. 1008 had roughly 1.75" additional tile, where 211 had close to 3", as it was above the lower rail of the balcony rail, which was installed with a 2" spacing.

Makes you wonder if slabs were already deflecting to the point that had to float thickset just to level floors. Great solution to sagging floor.

Quote (Spartan5)

In her first interview, she makes no mention of a noise like a wall collapse; describing the sounds as “construction knocks” or “renovation noises.” https://collive.com/mother-escaped-with-children-r...

Yeah, I was somewhat discounting that piece because it was so sanitized for the religious community. For example, we know from multiple sources that the kids were both awake (Gabe cooking salmon, Chani taking a shower) and not asleep. So I have felt that source was less reliable than the CNN interview where Sara Nir is very specific about hearing the "wall collapsing" at 1:10 am. Maybe I'm wrong...

Quote (Demented)

Unit 1008 and 211. 1008 had roughly 1.75" additional tile, where 211 had close to 3", as it was above the lower rail of the balcony rail, which was installed with a 2" spacing.

Thanks! Are these the only two units with that amount of topping? Is the source the 2018 MC assessment?

Could have even been just tile being added over tile for the sake of changing the tile every few years.


Not sure if this has been linked yet.
https://www.youtube.com/watch?v=Ltw77weRymA

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

Quote (MaudSTL)

Thanks! Are these the only two units with that amount of topping? Is the source the 2018 MC assessment?

With that amount, yes. The only two, no. Source is 2018 MC assessment as well as personal knowledge of the balcony railing job that was to be completed with the renovations. Field dimensions were to be verified after balcony work began because there was some inconsistencies in the as builts vs the drawn, and decisions needed to be made over filling existing core holes and using base plates with 1/4" x 2-3/4" 308L stainless tapcons (because rusting stainless on the beach is better somehow) or using existing core holes. Over the years there has been at least 100 unpermitted renovations to the balcony surfaces. Home Depot sells all the stuff you need.


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

Quote (CE3527)

… but there isn't any evidence the alarm ever sounded in the building. If it had, 6 minutes pre-collapse would have been plenty of time to wake people up and get them out.

I have a theory that I truly hope is wrong, and zero evidence to say it happened. Some fire systems are setup with a short delay before they go into full alarm, and it's been known in places like hotels for the guard or night receptionist to have a habit of cancelling the alarm and investigating, to avoid false alarms disturbing guests. It's a terrible habit that comes from frequent false alarms and bad decisions.

Another theory, is that some alarms don't go into full alarm from a single automatic detector or zone wiring fault, only with a manual pull point or multiple automatics. Some do a soft PA alarm to alert staff on the first stage, such as British railway stations paging "Inspector Sands" to the control room or office. The elevators might still recall on that type of alarm, until cancelled.

Quote (Demented)

The only two, no. Source is 2018 MC assessment as well as personal knowledge of the balcony railing job

Thank you! There's no point, then, in trying to track down Mr. Santini for his photos...he lost four friends in the collapse, and must be devastated. This collapse really hit close to home with you too. My condolences to all who lost acquaintances, friends, and loved ones.

I lost no one so my bother is in other ways. Not saying to track him down, but he may have knowledge of newer stuff. That railing bid started in 2019, so a lot could have changed since.

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

Quote (MaudeSTL)

Yeah, I was somewhat discounting that piece because it was so sanitized for the religious community. For example, we know from multiple sources that the kids were both awake (Gabe cooking salmon, Chani taking a shower) and not asleep. So I have felt that source was less reliable than the CNN interview where Sara Nir is very specific about hearing the "wall collapsing" at 1:10 am. Maybe I'm wrong...

What seemed sanitized about it?

The Post article cites a time of 1:14 per their interview with her.

And even in the CNN interview she refers to the wall collapse as “construction” noises and goes to complain about it not because she’s worried about the building, but because she’s annoyed that it’s happening at 1 am.

Quote (Spartan5)

If we entertain the idea that the penthouse collapsed at 1:10, why would it be that no one on floors 12->11->10… were freaked out by it and called 911 and/or boogied on out of there? Especially if it was supposedly heard so clearly on the first floor?

When the 911 calls were first released, the articles specified that they were the 911 calls from survivors... which indicates to me that there may exist unreleased 911 calls from non-survivors.

BKNJ

Brought to you via potato cam.
https://twitter.com/Zredroc

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

Quote (BKNJ)

When the 911 calls were first released, the articles specified that they were the 911 calls from survivors... which indicates to me that there may exist unreleased 911 calls from non-survivors.

That may be so. But there’s also been no reporting on their existence, regardless of the status of their release; e.g. “Sources report that concerned residents on the 11th floor called 911 more than ten minutes before the building collapsed…”

This article in the Miami Herald about the release of the 911 calls, makes no qualification that the calls are from “survivors” BTW.

Quote (Demented )

Interesting. They put a cone where each column should be located and it seems that at least one column is missing

Quote (Spartan5)

This article in the Miami Herald about the release of the 911 calls, makes no qualification that the calls are from “survivors” BTW.

I said 'when the 911 calls were first released'. I acknowledge that 99% of the articles out there do not specify 'survivors'... just like 99.9% of the articles out there specify erroneously that only 55 units were destroyed.

Anyway, WPLG Local 10 specified 'survivors'... it was one of the first sources of such info I came across at the time... https://www.youtube.com/watch?v=E2n2AjBOK0Q I don't know if they misspoke or what, but since it's an odd inclusion I thought it would be of interest. There was at least a second source that specified survivors, but I can't find it now.

There have been some aspects of this news story which have been very hush-hush, so it wouldn't surprise me if other calls or their existence would be glossed over at this time.

BKNJ

Quote (Murphy 9000)

Some fire systems are setup with a short delay before they go into full alarm, and it's been known in places like hotels for the guard or night receptionist to have a habit of cancelling the alarm and investigating, to avoid false alarms disturbing guests.

The original plans indicate that activation of a pull station, smoke detector, or flow switch will transmit an audible alarm to the activated floor only. It goes on to state that after 0-10 minutes, the system will then go into a general alarm, and tamper switches will annunciate but will not activate the fire alarm. Further it states that the elevators will return to the first floor "upon alarm".

The preamble cites Sec. 5100 of the South Florida Bldg. Code.

I obtained a copy of the code book dated 1994 and section 5103.1 states:

(e) All alarm signaling devices on each floor shall activate the alarm device on the signaling floor only and annunciate at the Central Control Station with the further provision that any or all such alarm devices shall be operable from the Central Control Station.

The 1979 plans show that both the fire alarm panel and alarm voice console appear on the first floor near the security office and electrical room.

This is not to say that the original 1980 system was still in place, but audible alarms only on the activated floor first does seem to be the standard.

I did not study the fire alarm riser diagrams thoroughly, but it appears that annunciators and speaker wiring could be compromised if significant structural damage occured near the first floor or garage.

Attached is a copy of the fire system plan from 1979.

• https://files.engineering.com/getfile.aspx?folder=fe15f254-b753-41b9-9065-c

That’s reading a lot into a YouTube title from a local tv station.

Quote (BKNJ)

There have been some aspects of this news story which have been very hush-hush,

Like what?

Quote (Paul Austin)

inspired by your cone-counting I tried lining them up. I also get a missing cone close to your red arrow (red circles), also one further to the left left (east) and further back, depending on how you line things up. I'm sure the CAD gurus will do a more formal job of this, but it is certainly difficult to find all the columns that should be there.

Quote (Paul Austin)

Quote (AusG)

Ummm... the more likely explanation is that the site safety
officer put a cone where there was a tripping hazard hidden below the water's surface.
There is no need to keep the column locations marked while the site is being demoed.
The remains of columns and all the other rubble have been moved offsite for further study.
The land will be cleared and made ready for a memorial or sold to a new developer.

The cones aren't always over columns. On-site folks are moving them around sometimes.

Yesterday, this cone was over a column but these people came by, chatted for a few minutes, then picked this cone up and moved it a few feet away for some reason. It remained there for the rest of the day.

The mini dozer was fighting a losing battle, the water level continued to rise, apparently coinciding with high tide. It is going to be interesting to see what the foundations look like under that slab.

Quote (microwizard)

...The mini dozer was fighting a losing battle, the water level continued to rise, apparently coinciding with high tide....

Or perhaps the water table is so high here. Reports say that standing water in the garage had to be pumped out regularly and often was a losing battle. Building Integrity YT channel actually talked about this in his recent video. He posits that the fluctuating water table level contributed to subsidence and that the water could have been leaching into the columns from below. He shows some photos from the garage walk thru that show possible water saturation at the base of the columns.

https://youtu.be/Kg7xofW6fnI

How did they pour the original slab, if there was (salt?) water to wade in?


spsalso

Quote (spalso)

How did they pour the original slab, if there was (salt?) water to wade in?


spsalso

Steel cribbing to be a make-shift damn that slows the water ingress is the standard here. Leave in ground or remove, typically remove if it's not at a remaining sea wall.

Was there a sea wall in the plans? Was the East facing wall in the parking garage what was intended to be the barricade between the ocean tides and the interior of the building? Water does flow 2-3ft below sea level here.

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

It's like the 'bathtub' underneath the World Trade Center - a lot of attention went to shoring it up during the recovery / cleanup efforts after 9/11. Looks like in this case, the 'bathtub' under the condo here had some leaks.

spsalso - another method they use to control water in big excavations like this during construction is called well pointing. Basically a series of pretty shallow wells that surround the perimeter of the excavation. The wells draw the groundwater, water table down in an attempt to keep the water from reaching the excavation.

As for these pictures, it doesn't look like they're trying too hard to keep it dry cause I only see a couple pumps. At some point they make a more serious effort at pumping if they want to get a better look at the slab and foundations.

Quote (BKNJ (Computer)17 Jul 21 04:25)

Anyway, WPLG Local 10 specified 'survivors'...

I have noticed that WPLG has better reporting. They have one of their reports on site every day, and dig for stories when the narrative is not being managed by the mayors and the governor...

SF Charlie
Eng-Tips.com Forum Policies

Well pointing on reclaimed ocean land would have been tricky. On the beach it's far easier to just build the temporary cribbing walls as you already have the pile driver there, and pump the water out. Plus it helps hold the sand together.

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

Thanks, all, for explaining things to me about the slab and the water, etc.

Always good to learn new things.


spsalso

Hello, I've been following this for a few days and it's been very informative.

Now we're in the demolition phase, I wonder if anyone saw the point where they dug down to the garage deck? By the time I saw it, they had already removed all the columns, so there was no way to tell if M11 (which is the one 'missing' in the TikTok video, right?) was on its side rather than standing in punch-through like all the others. We may be making a bit much of the column being 'missing' - after all you can't see M12 in that video either and we know that was still standing.

One thing that the demolition videos showed to me is that the lower rebar all looked in pretty good condition, where they'd ripped the columns out. It doesn't look like the water intrusion from the bottom had damaged the column-basement joints.

Teguci posted a very plausible natural deterioration scenario back on page 5. That slab step is not a shape that concrete enjoys, and it ran right behind a constantly wet planter in the L-M area. We all want there to be an inciting event because it's quite disturbing to think buildings like this could degrade naturally to a collapsing state - how many other buildings, then, might also be dangerous? What about CT North? (Although interestingly it seems that slab step doesn't exist there - maybe someone twigged it was a bad idea?)

The 'car rams a column' and 'roof parapet drops onto pool deck to start the collapse' don't work for me. The reports of noises well before the final collapse indicates that the building was already redistributing load, and if the parapet had fallen down to start the collapse at 12.30 then lots of people would have reported that.

I've enjoyed the analysis of the 711 video as well which tells us more about the final failure. One interesting thing with that, and the exterior security video, is it shows the collapse starting with the floors still spaced normally, i.e. floor slabs have not detached from columns yet (at least as far down as 7). But when you look at the rubble pile in the immediate aftermath photos, there are large sections of continuous column; the columns didn't get crushed between the floors, so in the final pancaking, they must have detached? Or are those near-complete columns from the eastern section, not the first collapse?

There's a few loose ends that don't make sense to me yet.

- The timing of those Argentinians coming back versus the TikTok video, the 'loud crash' from the Sirs, and the pool deck collapse. They got back so late that you'd think that crash, which people have suggested is the slab step or M9-M10 beam letting go, would have already happened, but they didn't see anything on entering the garage. Can you get into that garage from the Collins St side? It doesn't look like it. So what was that crash if it wasn't something falling within view of the garage ramp?
- What was the 'creaking' above 1211 the day before? It certainly sounds like the roof work had done some damage up at the top levels of the building. It's hard to see how that could contribute to a bottom-level failure though, and the columns at roof level (even if seriously weakened) are nowhere near their load capacity. Maybe it's just a coincidence that the roof and ground floor had problems at the same time.
- So many of the reports of noises were from 'above'. Does this just mean that concrete and/or rebar was under severe strain throughout the building already, making noises throughout the x10/11 stack?

Quote (Red Corona)

So many of the reports of noises were from 'above'. Does this just mean that concrete and/or rebar was under severe strain throughout the building already, making noises throughout the x10/11 stack?

Aside from the creaking, which could have been anything, all there was was 111.

The woman who escaped (from 611?) reported noises that caused her to go towards the balcony to investigate. I don’t recall her saying anything about noises from above.

What other reports were there?

Edit:

Quote (611)

Monteagudo, who is in her 50s, woke up from a restless sleep and heard strange noises. She initially believed they came from the open sliding door to the oceanfront balcony.

“I ran and tried to close it but I couldn’t, I imagine because it was unlevel already because of all the movement,” she recounted. “I heard a crack and when I looked, I saw a crack traveling in the wall two fingers thick. Something told me, you need to run.”

This feels like a fairly big stretch, but here's a hypothetical scenario for creaking in 1211 the night before. Keep in mind that the failure from severe overload progressed over years in Singapore's Hotel New World, so 24 hours isn't totally crazy.

The failure started in or around the M9.1–M11.1 beam the previous night. M9.1 cracked a little and dropped just a little. Let's say less than an inch, and it just looked like more miscellaneous spalling that they are used to ignoring. This wakes the lady in 1211 when there's a small bang and jolt, and she hears creaking as the structure around her complains about the new load distribution. A day and another thermal cycle passes, then the complex beam arrangement fails and brings the pool deck down, followed by the towers.

It seems odd that nobody else, particularly in the x11 stack, reported anything. Did they sleep through it? Was it small enough to be ignorable on lower floors, but something about the penthouse and roof structure amplified the stress up there?

Unfortunately, most of the people who could tell us about the small stuff they routinely ignored or accepted in that section of the structure perished in the collapse.

Could a lack of insulation explain it? In my building maintenance noises from the ground floor behind on other side sounded like they were coming from above me today. Just how the noise travels through the structure.

More potato cam. January 2019.

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

Quote (Red Corona (Computer)17 Jul 21 20:09)

I wonder if anyone saw the point where they dug down to the garage deck?

The BecauseSurfside channel has broadcast that on YouTube live, but I can't seem to find the video in their archive. I beleive it happened about July 14th...
Please see my post in part 6

Quote (SFCharlie (Computer)(OP)13 Jul 21 14:27)

Right Now, and since at least 6:40 PDT (9:40 EST) the search team has been ripping up the pavers midway between the pool and guest parking. They are sawing holes in the pool deck and removing the slab with an excavator.

Below is a picture of Unit 1010 posted on part 2 of this thread noting what appears to be deflection in the slab at the end of counter top (red circle). Not sure how long before collapse this picture was taken.

What has troubled me about this picture, and I don't think it has been mentioned, is the green area around Column K. It appears the slab had dropped in relation to it's attachment to the column, but somehow the slab is being supported by load transfer to other elements of the structure. Of course I am ass_u_ming that the baseboard in this area was actually flush with finish floor when the flooring was installed.

Shadows. Other angles of the same room show no deflection.

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

As I have not seen them posted anywhere after scrolling back through.

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

Thanks Demented. I was having a hard time explaining that one in my 'Vintage Brain'. I see something interesting in your pictures. It appears the sliding glass door frame is sandwiched on both sides by finish floor heights that are noticeably higher than original finish floor height.

4" spacing between those railing bars for the record. 3-7/8" if the shop that made them was as good as they claim they were back in the day. That's not a 2" spacing beneath the channel. I'm not having any luck finding any work permits for 1010.

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

That unit definitely has flooring that is substantially higher.
There was never any calculations figured in for all of these units being fitted with marble flooring, bathroom, kitchen counter-tops, or all of the added weight of hurricane windows either?

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

Finally. Original an condo unit.

Unit 212

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

*shrugs*
I'm still inclined to believe the pool deck failed first. There is definitely signs of settlement along that area.




Source of original.
https://images.condoblackbook.com/mls-units/357780...

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

Quote (Demented )

Was there a sea wall in the plans? Was the East facing wall in the parking garage what was intended to be the barricade between the ocean tides and the interior of the building? Water does flow 2-3ft below sea level here.

Permanent Site Bulkhead (orange) along the eastern lot line, 120’ west of the hardpack bulkhead (yellow). Retaining wall along the other boundaries. The bulkhead now visible visible along the south wall (green) was added in 2019 during construction of 87 Park. Blue is Tatum bulkhead, northern red is the assumed location of the old Biscay Island bulkhead, southern reds are the Normandy Beach bulkhead.

The west side of Collins Ave there was the eastern shore of biscayne bay with “The Quarry” located between Collins and the ocean at what is today 87th terrace and 88th St.

A sub-basement level exists below the garage slab.

Quote (AusG)

Thank you

Quote (3DSoftwareDev )

Quote (Nukeman948 )

officer put a cone where there was a tripping hazard hidden below the water's surface

I agree, the question is why there is no remnant of that column/s. The rest of the columns were affected by the collapse of the building but despite that they have big rebars left.


These are the totally non-existent columns.
Maybe it's nothing but I just bring it up.

Unit 511, images from March 2021
https://www.condoblackbook.com/surfside/champlain-...
611 above it for comparison. 611 was the resident who noticed the cracks at the start of the collapse.
https://www.condoblackbook.com/surfside/champlain-...

This unit appears it does have evidence of failure. That floor aint right. Door gaps are not even horizontally but are vertically. Cracking evident along single rows of tile. Sliding glass door is sunken in.



Maybe noises did come from above 111.

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

Throughout the TOWN OF SURFSIDE memo (ref Date: July 7, 2021) it REPEATABLY STATES:
"after GPR to AVOID reinforcing steel" when taking concrete core samples...

The M.C. Oct. 2020 report shows core samples that were taken of the C.T.S. pool deck concrete slab cutting completely through multiple reinforcing bars...
.



.
https://uc199e99c9a0c47ae8a72fd96a99.dl.dropboxuse...#

Quote (Demented)

This unit appears it does have evidence of failure. That floor aint right. Door gaps are not even horizontally but are vertically. Cracking evident along single rows of tile. Sliding glass door is sunken in.

The front doorframe to the building's corridor certainly looks twisted. It appears that the M column line has dropped a fair bit relative to the L line. Mentally extrapolating the gap at the top of the M-side door to the width of the L–M span, it could have dropped by more than an inch, assuming a uniform deformation across the span. That feels like a rather bad thing and sign of significant distress.

Maybe we are looking at some sort of compressive failure in overload scenario? If it hit the M line worse, maybe that could have failed the beam attached to M9.1 ahead of total failure, to collapse the pool deck ahead of the tower?

Quote (Demented)

This unit appears it does have evidence of failure. That floor aint right. Door gaps are not even horizontally but are vertically. Cracking evident along single rows of tile. Sliding glass door is sunken in.

None of those photos you posted show any indication whatsoever of failure. You are simply reading things into the photos that are not there to support your preconceptions.

It's twisting in the way we see in the "sudden" failure from room 711.

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

Quote (Retrograde)

None of those photos you posted show any indication whatsoever of failure. You are simply reading things into the photos that are not there to support your preconceptions.

My preconceptions are that tension cables or supporting rebar were damaged in core drilling (related to railing installs, not to concrete testing), as well as heavy rainfall of 2.88" the days leading up to the collapse causing the deck that needed to be replaced back in 2018 to fall below, causing a progressive failure taking the building down because the deck and building were holding hands basically. I could be wrong.

That pool deck and building held hands better than Jack and Rose.

I'm just simply trying to find any possible bit of any indication of a looming failure because I do find it hard to believe the building would just suddenly give way.

I've been on multiple ocean front projects in South FL from ground breaking to CO over the last 20 years. I now am only involved in the renovation side of these stupid ocean front homes. I don't trust a damn thing in this area especially after witnessing a building inspector and fire marshall pass shit after an expensive dinner at a strip club, but stuff usually gives us a warning before it gives up the ghost.

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

Tile is notoriously brittle - individual cracking just about never conclusively proves foundation issues. You really need cracks that span multiple tiles to start suspecting a foundation as opposed to water getting through or kitchenware getting dropped. And that lump near the balcony windows looks like water intrusion getting under some tiles and expanding the mortar. Poor sealing near the sliding doors and/or the balcony isn't sloped. This applies to any house, not just concrete high-rises.

Not sure I saw any issues with #511 main entry doors or entryway closet sliding doors. If we're comparing the straightness of wood post to RC slab, the wood warps first.

The pool deck, on the other hand, was very water logged, not just in photos but from witnesses who spoke of water sloshing around as they walked on the pavers in clear weather.

I have a background in food production environments. (Sometimes the only growing industry is food production, have to follow the money).

Anyways, often what occurs is that drainage and the concrete slopes never line up perfectly. Having had cleaned flooring on a daily basis, I could see this issue first hand.

Either the water finds a drain, evaporates in the air, or finds a crack in the concrete to alternative path its way into the slab, columns or foundation.

So one place I worked had a walkway where they had pallets on the ground against the wall. They stacked made up cardboard boxes along the wall. Opposite to this they had fridge entry sliding doors with drains.

So, unfortunately the water pooled under the pallets. And no cleaning was performed unless an audit was due. Where the water was pooling the concrete seemed to sink slowly over time, so the pooling got even worse.

Pooling water on a concrete surface is often ignored, but there is degradation occuring here. Even in a building with temp control this is a problem. Water simply shouldn't be allowed to pool up on concrete without some solution being created. Maybe you grind back the concrete and add more to increase the height?

It might be a mistake to assume misalignment of the visuals in that apartment happened recently.

It's possible it was always that way.

There are hints that the quality of construction was far from the best!


spsalso

Speaking of construction quality, the Miami-Herald reports that the CTS structural engineer Sergio Breiterman had previously signed off on a project that was not constructed according to plans.

#511 was heavily remodeled, since they completely removed the wall between the kitchen and the multiuse area. If the contractor was sloppy, the floor cracks in the kitchen could simply be from the lack of proper floor prep.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

Quote (Sergio Breiterman had previously signed off on a project that was not constructed according to plans.)

This just gets better and better...

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

-Dik

[Quote IRstuff][/#511 was heavily remodeled, since they completely removed the wall between the kitchen and the multiuse area. If the contractor was sloppy, the floor cracks in the kitchen could simply be from the lack of proper floor prep.]

What is concerning about all the removing of a wall like kitchen area, is that takes a distributed load and converts it into two point loads.

Oops: I am ass_u_ming again that headers were installed where walls removed. Based upon the quality of work, and lack of consideration for structure with all the alterations, it is more likely that no header was installed where walls removed.....

Thus constantly changing load paths from possibly under nourished slab, as walls are removed or added in individual condo's with no consideration of how that affects the structure below or above a particular stack of units.....

So this other parking garage project had CMU vehicle barrier walls with an identical detail to the parapet walls at Champlain. Tie columns at 20' on center, with 4 vertical bars at each column. But they found the garage had only 2 vertical bars actually installed. For what it's worth, I've noted all 4 bars visible in some of the parapet wall debris at Champlain. But it does reinforce the general stereotype of shady contractors skimping on details in that time period. Another recent article claimed several thousands of dollars of building materials disappeared from the Champlain site during original construction and that an inside job was suspected at the time. So it's not a stretch to suspect contractors "strategically" omitting rebar here and there where they thought they could get away with it - say at a slab construction joint...

Quote (Thermopile)

What is concerning about all the removing of a wall like kitchen area, is that takes a distributed load and converts it into two point loads.

I disagree. This isn't a wood-framed house. The columns in a concrete structure like this are the primary load-bearing elements, so I doubt the removal of interior unit walls has much of an impact. The only walls that would make a difference would be the few shear walls around the vertical circulation cores.

Interior partitions for this are likely non bearing and have no significant effect on the structure... some codes prescribe a fixed partition load of about 20 psf...

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

-Dik

3DSoftwreDev,

The flat slab is supported by the columns. However, an under nourished slab will deflect. The amount of deflection depends on dead and live loads on the slab. Shifting walls, increased weights of thick set ceramic tile vs original vinyl and shag carpet all affect the load on the slab that gets transferred to columns.

When originally built any weakness in slab to column joints would shift some loads onto partition walls. Say apartment 411 removes some original partition walls, then unit 511 adds 3" worth of hard tile flooring plus heavy built-ins to their floor slab.

What do you think the effect of this will be on 411's ceiling shared slab?

I am sure there are plenty of experts that can explain this better than I can......

Edit: In a perfect world where slab, columns and joints are designed and built properly for the applied loads, there would be no issue in removing non-load bearing walls. But does anyone on this forum think this is the case, after the data that has been presented?

Edit 2: Shifting loads from one under nourished slab to another can shift additional load to column slab joint on lower floor.

Almost every X11 and X12 unit had the interior partition walls in the kitchen and laundry/electrical room demod.

Don't forget the addition of impact rated windows and glass doors that were to replace the traditional windows and metal accordion shutters.

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

I'm not really seeing anything much of concern in those 511 pics. Any deviation or cracking in surface materials is likely just due to poor workmanship in laying the new floor imo - you can't see the structural members. The only one for me is that the main doorframe doesn't look rectangular (normally when doors don't fit it's because they've slipped on their hinges, but that doesn't look true here), which if it was properly built in the first place would indicate a parallelogram effect consistent with M columns dropping relative to L. But honestly I'd probably suspect the doorframe not being properly aligned in the first place.

Going back to the punch through columns, in photos from the next day (posted back on threads 2/3), it does look like there's a lot less top rebar than there should be in a lot of those. Some of you posted about that at the time. If that were true in the building as well as the deck then it would make slab detachment a lot easier. But it doesn't seem that was a major factor until the collapse was already under way to me.

Are buildings like this really designed with no redundancy? I think we all agree that the trigger for the main collapse was M9 failing at ground floor level (though there are different reasons offered for what caused that to happen). But surely losing one column shouldn't cause a whole building collapse?

If you have ever installed a prehung door unit where floor slopes parallel to threshold, and you just set door frame on sloping floor, you will end up with gaps at top like the one pictured. Installer can easily plumb sides with shims, but it difficult to solve un-level floor from one side of jamp to other. And a double door just magnify’s problem.

1972: Breiterman certifies a building that has inadequate rebar and poor waterproofing. It is a building built for the city of Coral Gables, just 8 miles from Surfside.

1976: Newspaper article in local paper points up the failing noted above.

1980: Breiterman is chosen to work on Champlain South, where it appears he again certified a building with inadequate rebar and poor waterproofing.

People in the Surfside building department must have been aware of the earlier problem (newspaper/8 miles). I am surprised their inspectors were not more aggressive in their inspections.


spsalso

Quote (Thermopile (Aerospace)18 Jul 21 17:48

The flat slab is supported by the columns. However, an under nourished slab will deflect. The amount of deflection depends on dead and live loads on the slab. Shifting walls, increased weights of thick set ceramic tile vs original vinyl and shag carpet all affect the load on the slab that gets transferred to columns.)

This may be irrelevant to the general hunt but with reference to the 8” condo floor slabs.

Bending rebar: The top and bottom flexural reinforcement provided on the project is not really lacking, perhaps the placement over columns could have been better but there is not an alarming deficiency at all. Slabs generally do not fail in bending anyway.

Punching rebar: It is unclear if any punching shear reinforcing was provided, suffice to say that using today’s codes it would very definitely be required. Some codes even advise on consulting specialist literature for slabs thinner than 8”.

Deflections: A quick run shows elastic (immediate) deflections of these typical 8” floors, with only dead load (self-weight, finishes and limited cmu), are less than ¼ “ for the typical 22’ spans. Theoretically, long-term deflections range from around 1” (grid 8 to 10) to 1 ½ ” (grid 8 to 4).

Fwiw, the dividing walls had reinforcing bars placed at their base (sheet 6) so would have tried to span between columns and behave like beams.

The big question is, how much of the designed rebar was actually not in the structure as built and where? It also appears that it varies from place to place and pour to pour. Like perhaps the contractor knew in advance what areas Breiterman would sample inspect, and perhaps those areas were correct. But other areas the contractor knew would not be sample inspected, got less than design rebar? Coupled with many other parameters.

Say for argument's sake, what is 1/2 rebars missing in some slabs? What would deflections be then in those areas?

I guess we are to the point, where we are waiting for the field verification data to be loaded into the models and compared against design data to have a better understanding of how all the parameters played together?

Quote (Red Corona (Computer)18 Jul 21 19:35)

Quote (Are buildings like this really designed with no redundancy?)

While there are many columns, each slab segment is designed to span only to the original columns. Take away one column and the slab must span twice as far, with much higher moments and the lower reinforcing spliced at the missing column location. Thus theoretically and in simple terms, the positive moment demand has increased by as much as 4 times at the lost column location and the positive reinforcing is spliced there, resulting in zero contribution. Result - collapse.
Basically the only redundancy is the safety factor - the capacity/demand ratio - and that is never designed to be 4 in a market like this. Had the engineer designed for slab spans twice as great, he would have left out half the columns and made those remaining larger.
If everyone is designing and constructing buildings this way in 1980, that defines the market price for buildings. How do you sell better quality in a building during a gold rush boom? Better wallpaper, marble floors - what?
Realtors tout "location - location - location." A prime location has just become available.
At an enormous horrendous cost.

Where them roof first guys at?
Our potato cam crane operator friend gave ya'll a present.





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

Something important might be in that how many years do people expect a condo to stand for? They do all the repairs, how many years do they get out of this structure?

Perhaps a building should be inspected as to how long its physical presence should be anticipated? Is 40 years too long?

The building I'm sitting in right now is 108 years old. It's big need is replacing the (original) cedar shingles on the west wall--maybe next year. Over its life, so far, it's been taken care of pretty well, and "updated" pretty well, too.

It's easy to work on, and a relatively simple wood frame design. I would expect 200 years or more.

FORTY YEARS TOO LONG????????




spsalso

Quote (w-streng)

Punching rebar: It is unclear if any punching shear reinforcing was provided, suffice to say that using today’s codes it would very definitely be required.

I do not agree. I have seen loads of recent slab designs to modern codes where punching shear reinforcement is not required in a 200mm thick slab.

Demented, did he say these were found on the ramp area?

Some of that gear could fit within that 'debris' beyond the entry gate. It would be even better if they'd just come out n say it...

Edit: That kettle wasn't on the roof, or wasn't supposed to be. It could have been sitting on the North side on top of one of those "parking garage" roofs... kettles can way 2000 lbs or more. I wonder if that's why the FFs couldn't get thru that garage area?

Miriam Notkin and her husband from Unit 302, filed a complaint to the Town of Surfside regarding the horrible odors from the roofing operation, she wrote about the crane and kettle being very close to the building.

Link
In chrome translate to english..

Nicolás Vazquez "The smoke, dust, and " unbearable weird smell " also prevented them from breathing normally."

Can tar kettles catch on fire if unattended?

Quote (Demented )

Where them roof first guys at? Our potato cam crane operator friend gave ya'll a present.

I'm sure you realize that these pictures prove nothing without context, right? Were they on the roof that was part of the original collapse or from the July 4th demolition? Where and when were they recovered? Is Jimmy Hoffa's body in the tar buggy?
The existence of these items and their condition don't prove any one theory over another.

Zoom in, see for yourself.

Quote (Nukeman948)

I'm sure you realize that these pictures prove nothing without context, right? Were they on the roof that was part of the original collapse or from the July 4th demolition? Where and when were they recovered? Is Jimmy Hoffa's body in the tar buggy?
The existence of these items and their condition don't prove any one theory over another.

The above post is why I posted it. I knew someone would have where it came from. Sarcasm doesn't translate very well over the internet, and in my own sick mind I was poking fun at the blurry image CSI roof first people who I am sure had every bit of items on the roof mapped out.

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

Quote (Optical98 )

Zoom in, see for yourself.

When I zoom in I run out of pixels just before I can read the serial numbers on that equipment.

Right then Obie came to the realization
That it was a typical case of an American
conspiracy theory, and there wasn't nothin'
He could do about it, and the judge
Wasn't gonna look at the twenty-seven 8 by 10
Colored glossy pictures with the circles and arrows
And a paragraph on the back of each one explainin'
What each one was...

Ok, so adding an image directly turns it into a potato...

Let's try story time again Nukeman

Link

Also, please note my remarks regarding the tar kettle, the large one that looks burned up, not the small ones on thee roof..

Different view

Quote (Nukeman948 (Electrical)19 Jul 21 01:08)

Colored glossy pictures with the circles and arrows
And a paragraph on the back of each one explainin'

Ain't often we get a quote from Alice's Restaurant
Nuk-yoo-lur 'cause you study the Nuk-yoo-less of them there atoms?

SF Charlie
Eng-Tips.com Forum Policies

Quote (Optical98 (Computer)19 Jul 21 01:37)

see for yourself

Yep!

SF Charlie
Eng-Tips.com Forum Policies

Quote (SFCharlie )

Nuk-yoo-lur 'cause you study the Nuk-yoo-less of them there atoms?

Worked at 5 different nuke plants. Palisades and DC Cook are my favorites.

Me and Woody Guthrie's son Arlo are just chillin' on the group W bench.

Quote (Nobody in particular)

Green

So, is the green saw the green object in the "water streaming in the garage" video???

SF Charlie
Eng-Tips.com Forum Policies

Quote (SFCharlie )

Green So, is the green saw the green object in the "water streaming in the garage" video???

Not a chance, it would have been Much more damaged after falling 13 floors and crashing through the
pool deck.

Two different people see the same picture and come to totally different conclusions as to what they see. That "saw" is actually a power sweeper.

People post pictures here and ask us what we see, but they won't come right out and say what they see.

Quote (Nukeman948 (Electrical)19 Jul 21 02:06)

power sweeper would have been Much more damaged after falling 13 floors and crashing through the
pool deck.

Yes, I had been thinking the same of the tar kettle, but how did they remain uncrushed as the black car is flattened? Did the material they were on cushion the blow, or were they on the pool deck already?

SF Charlie
Eng-Tips.com Forum Policies

Quote (Optical98 (Computer)19 Jul 21 00:45)

Zoom in, see for yourself.

So where's waldo, ups, I mean the tar kettle? Forgive me for being old with bad eyes, but I've been scanning and scanning the high res you provided, and not coming up with anything?
Thanks

SF Charlie
Eng-Tips.com Forum Policies

Quote (SFCharlie)

Yes, I had been thinking the same of the tar kettle, but how did they remain uncrushed as the black car is flattened? Did the material they were on cushion the blow, or were they on the pool deck already?

When I look at that picture of the flattened black car and tar buggy I see debris UNDER the car. I don't think those items are exactly where they were immediately after the collapse.
Once again, a picture without CONTEXT tells us nothing.

STOP posting pictures without Context and making up stories to fit you bias and stop trying to get me to believe your nonsense.

(that last sentence was not directed at you, SFCharlie)

Edit to add: I've worked construction for 35 years and have seen tar buggies and all sorts of other construction equipment parked in parking garages just like this one and that one MAY have been parked close to where it is in that picture. There were large voids in the collapsed area near the pool and the retaining wall. (Now I'm just speculating without context.)

SF Charlie,

The reference from Nukeman (aka Roofing Contractor's Ins agent)was that the roofing items may have been on the "still standing" roof prior to demo. My thought was that there are ample photos of said roof, so I added the pic. But it doesn't transfer over to this site well enough to zoom in as clearly as I can see it on my compy.

My point was that the items are not seen on the roof prior, however there were some smaller kettles up there. I am curious as to where the larger kettle was found, I don't think it was on the roof btw.

Below zoomed in on small kettles -

Nukeman you seem highly emotional and overly reactive to a calm discussion here..

Quote (Optical98 )

Nukeman you seem highly emotional and overly reactive to a calm discussion here..

LOL

EDIT: you called me the roofing company's insurance agent? And you think I'M the one that's getting emotional? LOL

But I'm not speculating about the complaint from unit 302 Nukeman, it's contained in the documents. I will find it and add it to give you more CONTEXT.

re the flattening, it might have been parked up off to the side somewhere and not taken the full force of a descending slab. The cars are mashed to just over knee height by the looks, so that does leave some space.
also, been meaning to ask you guys...are these briefly-appearing spines the columns peeling out between the first and second collapsing sections of building? They appear at 03/25 of the CCTV and seem to me to be emerging between those two sections before rotating forwards and falling. If so they are already higher than the roof of the first falling section and give a visual guide to how much it had settled before the video starts.

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

Quote (Optical98)

Optical98 (Computer)19 Jul 21 00:19
Miriam Notkin and her husband from Unit 302, filed a complaint to the Town of Surfside regarding the horrible odors from the roofing operation, she wrote about the crane and kettle being very close to the building.

Link
In chrome translate to english..

Nicolás Vazquez "The smoke, dust, and " unbearable weird smell " also prevented them from breathing normally."

Can tar kettles catch on fire if unattended?

I was looking at this earlier. I was wondering if the crane to move the stuff on the roof and other heavy equipment was sitting on the road or on the deck that makes up the roof of the garage. There was an account more of the roof work in the HOA letters on the Town floor of Surfside website. https://surfside.one/public-records-search/



Reading through everything I’m leaning towards the pool deck being the start of the failure. The 2018 report notes that there were repairs on the slab and that the cracks were continuing on from the repairs. To me this signals that the slab may overloading and previous repairs did not address the root of the problem. It also notes that the areas under the planters as being noticeably worse then the other areas.



I feel like it was only a matter of time for the slab to fail. I feel like a major part of it was the water deteriorating the strength of the concrete.

With no comment on what triggered this collapse, I think many here would agree that the effects of deterioration from a costal environment had reduced the reserve capacity of this structure. To what extent is yet to be determined.
So that brings me to the question - are there any FDOT structures in a similar environment that have survived 40 years? Have they required significant repairs and/or restoration in that timeframe? This is a serious question - I have not worked in a costal environment and would appreciate comments. Perhaps buildings should be designed, detailed, and constructed like traffic structures in coastal areas.
I would suspect the FDOT structures are inspected on a routine basis, perhaps something less than 40 years.
I will await test results of cores of the pool deck/plaza slab taken near the columns supporting that deck. The quality of the concrete at the time of collapse may be less than assumed in the design.
The results of core tests of the slabs near interior columns may shed light on what appears to be something other than failure in diagonal tension.

The Crane and Kettle were on 88th street:

Optical98

Yes tar kettles can catch on fire whether tended or not. It has been 51 years since I tended a roofing tar kettle, but they catch on fire very easily.

Jim

https://youtu.be/HPwJ0JvTcg8

A simulation of the collapse has been
posted to youtube. Description text reproduced here for discussion:

================
Published on Jul 17, 2021
On the 24th of June 2021 at night, the Champlain Towers South, a 12-story beachfront condominium in the Miami suburb of Surfside, Florida collapsed partially. This collapse simulation was made based on the presently available data, eyewitness, and video accounts.

The authors are independent researchers and impartial hoping to constructively contribute to the fact-finding. This study demonstrates the collapse mechanism assuming the following plausible hypothesis:

According to the data, the basement deck showed signs of extended soaking for many years. The problem was locally insufficiently patched and not rectified in its entirety. The wetting caused the deck ceiling to be weakened to such an extent that basement pillars punched through the deck where additional load had peaked at the planter area.

The authors hope to not distress relatives of victims with the application of dummy dolls in this simulation that have the sole purpose of tracking victims in potential cavities within the debris.

The Bullet-Constraints-Builder simulation software is open-source, it was developed within the EU FP7 funded INACHUS framework.

Kostack Studio was supported by Architect Oliver Walter with the data analysis.

Main sources:
https://youtu.be/KR29pLccutY
8777-collins-avenue---preliminary-review-plans-for-40-year-re-certification.pdf
8777-collins-ave-1979-plans.pdf
8777-collins-ave---unverified-inspection-report.pdf

Credits:

Simulation & video by Kai Kostack
http://kostackstudio.de

Consultant: Dipl. Arch. ETH Oliver Walter

Music:
Sergey Cheremisinov - Fog (CC BY)
Kevin Hartnell - Aurora (CC BY)

Made with Blender + BCB + Fracture Modifier
https://blender.org
https://inachuslaurea.wordpress.com
https://blenderartists.org/forum/show...

The "BCB" structural simulation software has been developed at the Laurea University of Applied Sciences, Finland. Written within the scope of EU Inachus FP7 Project (607522): Technological and Methodological Solutions for Integrated Wide Area Situation Awareness and Survivor Localisation to Support Search and Rescue (USaR) Teams

Some frames of interest from the simulation:

The presumed origin of the collapse, with pool deck and building shown:


Same view with deck and building hidden, revealing structural members:


Bright red presumably highlights the elements that will fail (have not listened to the audio):


This closely approximates the initial frame of the CCTV film:


Center section has collapsed, still-standing eastern section begins to tilt westward:


Collapse of eastern section well underway:



Now stepping back in time:

This camera is the closest one to the Tiktok video that I could find. Someone else may be able to identify the columns. I believe the vertical yellow surface at left is the eastern stairwell shear wall; we are looking south-southeast as though parked in the northernmost row of the garage. The ramp should be obscuring our view to the left. I may be misinterpreting the view.


The pool deck has punched through and almost come to rest.


Some comments:
I am not sure I see the “step” in the slab that is shown on the drawings. Is this area modeled correctly?

The collapse progresses without delay in the simulation. I would love to know how much they had to fiddle to get it to look this close to the actual collapse, or if it readily produced this outcome given the model that was provided.

Quote (rodface (Mechanical))

That is a well presented simulation. The view from the adjacent balcony gives it relativity to me.

In watching the video of the collapse at "Main sources:
https://youtu.be/KR29pLccutY" I do not see any disturbance of the pool surface - the reflections appear stable to me. Bad eyesight?

Quote (I am not sure I see the “step” in the slab that is shown on the drawings. Is this area modeled correctly?)

The slab steps are in the model but they appear as beams when the slab is omitted to show the framing. Only the vertical portion of the step is shown. (In the shots that reveal the framing.)

I did notice the beam38's are missing from the east stairwell.

It's very interesting that they show some initial failure on the north side. Starting at about 4th floor down to lobby level. Makes me wonder what information that is based on.

Quote (spinspecdrt)

It's very interesting that they show some initial failure on the north side. Starting at about 4th floor down to lobby level. Makes me wonder what information that is based on.

I wouldn't discount the possibility that limited analysis of root cause was done in producing this model. Working out which column likely failed first isn't the hard part. Working out WHY they failed is. And although it is a very impressive model this is a model of HOW not WHY.

Quote (Spinspecdrt)

It's very interesting that they show some initial failure on the north side. Starting at about 4th floor down to lobby level. Makes me wonder what information that is based on.

I was reviewing witness statements today, and discovered several details I had previously missed that could be related…but nothing specific to the fourth floor.

Remember that Gabe Nir has stated in multiple interviews that there were three stages to the collapse: Knocking noises and a crash from above, the deck collapse, and the building collapse. “Gavriel Nir tells the network that the collapse occurred in three stages and took a few minutes. First, he and his family heard noise from above and saw dust falling. They then heard a boom that they thought was an earthquake and rushed out of the building. Finally, from outside, they saw the collapse, with white clouds of dust following them as they ran.” Times of Israel

After the first collapse described by the Nirs in 111 as sounding like a wall collapsing in the apartment above them, both Gabe and Chani mentioned that they saw “dust falling” (Gabe) and “white particles” (Chani.) This seems to support the possibility that they really did hear a crash from above, as they all have described, instead of from below. They would have seen the falling dust between 1:10 am, when they heard the first collapse, and 1:15 am, when Sara Nir was in the lobby complaining about the “construction sounds” that they were hearing and then the deck collapsed. In one feature that quotes Gabe, he also says that dust started blowing into 111 from the patio, and he felt “the ground was shaking.” This new simulation depicts the deck collapse starting in the garage and expanding out to the deck, which would be compatible with how Gabe describes what happened between the first collapse and the deck collapse.

By 1:15 am, Gabe and Chani were standing in the doorway of 111, and ran to the lobby to join their mother as the Vazquezes were getting off the elevator. So nobody was still inside 111 as the deck collapsed.

I also found some new information that is interesting. There now may be a third driver who was in the garage right before the collapse: Sara Nir. Apparently, she was at an activity with her religious community, and Gabe was at the gym working out. Sara picked Gabe up at the gym on the way home. They arrived home to 111 at 12:30. The article does not state explicitly that they parked in the garage. But if they did, we now have three vehicles with survivors who have not mentioned any damage in the garage immediately prior to the collapse:

• Eric and Tamar Zion(at about 10:30, 11:30, and 12:30)
• Sara Nir and Gabe Nir (at around 12:20 or so)
• Nicolas Vazquez and Gemina Accardi (at about 1:00-1:10)

Quote (CE3527)

Interesting that their very first visible movement is a rotation inwards and falling away of some facade panels on the ground floor. I guess the unvisualised beam failures below them freed them up to fall.

The deck slab fails inside the footprint of the building next, the pool deck columns are just starting to punch at that stage. I think they have moved the locus of first failure a half-span north from most analyses here.

Nice picture, but the building clearly fell in three (3) parts, that shows two. There is probably little to no real physical accuracy there.

If M-10 fails on 1st floor, how does that lead to pool deck collapse before the building? It would seem the occupants of #111 would notice the left corner of their living room explode - or if sheetrock somehow contains that, at least the wind ought to exit the unit, not enter.

It pains me to rely on details from a NYPost article, but if dust was rushing into their unit, perhaps I'd be more inclined to suspect L-10 at basement level.

Or it could be a basement column further south. I'm unsure precisely how well concrete transmits structure sounds. I know it doesn't compress well, so it logically transmits shock very well and could misdirect a listener just like an echo chamber.

Concrete structures transmit sounds from bottom to top or top to bottom very well and are difficult to soundproof. Basically they are echo chambers. You can tell if something fell on the floor immediately above your ceiling, but all other sounds could have origins from the roof to the cellar.

I just want to make it very clear, I don't believe in roof first.

It appears the image Optical98 posted of the roof actually doesn't show the roof sweeper. I thought it did, but while looking for that trailer I spotted this in an image I circled of the roof leak and drains that don't do shit but flow once the roof is fully flooded.
Same colors, different machine. Typical of industrial tools.




Optical98, thank you for this picture!


It appears this would have been by the lobby entrance area, on top of the deck? 2 ton tar tank (~800-900psf if left full for next morning as is typical of the area). This wouldn't have been parked under ground in the garage would it have been?

It's right around the intended maintenance parking:

• https://files.engineering.com/getfile.aspx?folder=04aca84e-112e-4a25-9496-0

Quote (Demented (Industrial)19 Jul 21 10:07)

I just want to make it very clear, I don't believe in roof first.

Frankly, I don't really care what religion you subscribe to but feel free to contribute evidence or reasoned thought to the discussion. I can draw my own conclusions.

Even if I think something or someone is a complete wingnut, a different approach may tweek an open mind towards the true solution to the riddle.

I initially thought collapse along L, then along M, and have come back to L line. Two main reasons. L is more central to the collapse in the video so makes sense the collapse originated in the center. Two, the observable deformation of the room in the ring video is much closer to the L line then the M line. I don't see how the L corner of the room is deforming if failure is occurring along M. It's true though, the progression of the collapse is a discussion of "how", and the real mystery is the initiating event which I still think is rooted in the deck with some combination of bad design, bad construction, and neglected maintenance over 40 years.

The simulation seems to show the first elements collapsing are the ground level wall panels. I suppose that would sound like a wall collapsing. I wonder what their basis is for initiating those wall panel failures.

Also the view of the rubble heap from within the garage matches closely what I saw in my squinting analysis of the tick tok video, showing the edge of the slab, planters and the broken M11.1 column and beam.

Edit: looking at a different angle in the video, it seems they have M11.1 remaining standing (under the planter) while M10 collapses early on. This doesn’t match what I believe the tik tok video shows. I’m not sure they accurately accounted for the beam connecting those two columns.

Quote (Optical98)

But I'm not speculating about the complaint from unit 302 Nukeman, it's contained in the documents. I will find it and add it to give you more CONTEXT.

My point has always been that a picture of items that may have been moved or damaged when they were dug up doesn't tell the whole story. A description of time and location and what led up to the condition they were in can make all the difference.

And the complaint from 302 didn't help much either. Where were the items at the time of the collapse?

Quote (warrenslo)

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

This is my big question. Why does the video start the instant of the collapse? The frames just before could tell us a lot. Why wouldn't all footage of this building be released to the public, exactly for the type of speculation we are having to help understand what went wrong.

Florida's Sunshine Laws should hopefully help with all this, they are the most open state in the nation with public info.

Quote (sym.p.le)

Frankly, I don't really care what religion you subscribe to but feel free to contribute evidence or reasoned thought to the discussion. I can draw my own conclusions.

Even if I think something or someone is a complete wingnut, a different approach may tweek an open mind towards the true solution to the riddle.

Care to elaborate? What does religion have to do with anything?

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

It’s an analogy.

Most people here are agnostic.

A few others are expecting that they will ascend to heaven while alive aboard a UFO after ingesting fatal doses of phenobarbital and putting plastic bags over their head.

Something like that anyway.

Quote (Most people here are agnostic.)

Bad thing to be... the problem is that one of the main tenets is that the truth will 'never be revealed to you'... not a good thing for an engineer.

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

-Dik

Quote (dik)

Bad thing to be... the problem is that one of the main tenets is that the truth will 'never be revealed to you'... not a good thing for an engineer.

That’s not a tenet I’m familiar with. [edit: I am familiar with the concept that science and religion are diametrically opposed in that way; that the “truth” is discovered through observation in the former and revealed through regurgitation in the latter. Maybe that’s what you were driving at.]

(As an aside, someday I’d like to help you sort the quote feature. You’re a poster a value and your use of it makes things tough to follow sometimes.)

Quote (Thomas Henry Huxley)

Agnosticism is of the essence of science, whether ancient or modern. It simply means that a man shall not say he knows or believes that which he has no scientific grounds for professing to know or believe.

We digress. For the sake of the analogy, it’s not necessary to plumb the depths of theology. But we’d both agree that it’s way to be early to professing faith in one particular god or another at this stage of the game. And even once it’s sorted there will still be an unfortunate abundance of Truthers about us.

Quote (JTBuTexas)

This is my big question. Why does the video start the instant of the collapse? The frames just before could tell us a lot.

I believe the assumption is that the footage is from a motion sensitive camera. Meaning there are no prior frames recorded to examine.

I'm happy with the quote feature... I don't need to attribute the quote to anyone... just note that it was an earlier quote.

digressing... the great philosophers have not sorted things out in several millenia... I likely won't in my short lifetime... I'm part of the ignoranti. I don't worry about such important stuff... and am happy about it.

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

-Dik

Quote (dik)

digressing... the great philosophers have not sorted things out in several millenia... I likely won't in my short lifetime... I'm part of the ignoranti. I don't worry about such important stuff... and am happy about it.

Philosophy being one thing, and engineering a another, I think we can agree to…

“… follow your reason as far as it will take you, without regard to any other consideration. And do not pretend that conclusions are certain which are not demonstrated or demonstrable.”

I have never stated that I was posting conclusive evidence ...on any hypothesis.

I ask questions and post pictures on different findings, often to help others.

My first post and query was regarding the Generator Room, because there were plans stating that the floor/slab needed reinforcement. Even if the new equipment was never installed, there was indication that they'd found weakness in that slab which is over the ramp entrance area.

Also, many talk about the upper parking collapse on the south end of the building, but don't realize that the North end had a collapse as well. This is why I'm curious about the placement of the crane and large tar kettle. Several witnesses mentioned hearing a loud boom or even an explosion.

Adriana and Roberto Castillero said they saw the ceiling of the garage collapse, THEN looked up and saw people up on their balconies looking down trying to see what happened, she started taping the water leaking in the ramp entrance area and yelling for the people to leave.

Nicolás Vazquez "The smoke, dust, and " unbearable weird smell " also prevented them from breathing normally."

I've never promoted the Roof theory, but I don't dismiss it either. Same for the pool deck theory. I'd love to know what the debris on the ramp was definitively at some point.

As things calm down more interviews will be had and more videos and photos will emerge, we need to stay open minded and willing to discuss there meanings.

Quote (Optical98)

Adriana and Roberto Castillero said they saw the ceiling of the garage collapse,

This is incorrect. They did not see the garage ceiling collapse. Instead, they heard a loud noise while swimming in the pool, got out and went over, and then saw rubble and a gushing pipe in the garage entrance. Adriana Sarmiento started videoing at 1:18 am.

There has been a lot of telephone game and paraphrasing of witness statements both in the media and on this thread - but because they were on the spot what they saw and experienced is extremely important and needs to be accurately documented.

The most accurate news stories I read were from the Washington Post (WAPO) and the Associated Press (AP) story printed in The Republic. This was especially helpful regards the Nir family. In addition Sky News had an interview with a significant direct quote from Cassondra Stratton’s sister.

1) 410 Cassondra Stratton / roof work, vibrations and sound of running water

Images from her blog showed that she had moved to unit 410. Also news stories made a point of later saying she was not in unit 412 but established she was on the fourth floor.

The most accurate description of Cassondra Stratton’s conversation with her husband was an account from her sister, who was interviewed by Sky News. No other news story had specific quotes of she said and in order. The interview quotes the short video interview with the sister word for word, as she was standing on the beach in front of the collapsed CTS. The video interview is included in the article.

First, Cassondra was on her balcony (which afforded a clear view of the pool deck) upset, and calling her husband in D.C, waking him up. Perhaps she was awake and on the balcony because she had heard the same loud noise that prompted Sarah Nir in 111 to run to the lobby and Maria Iliana Monteagudo in 611 to wake up. We don’t know what it was but we do know it upset her. We don’t know how long they talked before the pool deck failure. In a Herald article her husband said, “She was frantic.” And from a Local10 article “Suddenly he heard his wife, Cassondra, speaking frantically about their oceanfront condo building trembling.” According to her sister, Ashley Dean, this is what she then said, seemingly interrupting their conversation:

“Suddenly she says, 'honey the pool is caving in, the pool is sinking to the ground'," Ashley recounts.
"He said 'what are you talking about?' And she says, 'the ground is shaking, everything's shaking' and then she screamed a blood curdling scream and the line went dead."

In a reference to a WAPO article, this was a quote from Ashley: “She screamed bloody murder and that was it,” Stratton’s sister, Ashley Dean, told The Washington Post.”

Ashley talked to Cassondra’s husband Michael (both flew to FL to wait at Surfside). Given the circumstances, it is very likely that he remembered the last portion of the conversation well, repeated it to her, and that she repeated it verbatim.

This suggests there was first something that made her go out on the balcony at that late hour. Something made her “frantic” according to her husband but we don’t have any quotes on what that was, and how long they talked about it. Perhaps it took some minutes while she attempted to explain it and perhaps he tried to calm her down. While on the balcony talking with her husband she first observed the collapse of what we know is the pool deck. Then it appears that very shortly after the pool deck collapsed the building began shaking and then that section of the building began to fall. Many other articles reversed the order of these two things in their paraphrasing of the phone conversation, or left one of them out.

This account is actually in line with the experience of the Nir family once you get to the accurate reconstruction of events that they experienced (I will explain that the mother’s account was embellished and inaccurate in several ways).

In addition, there is this additional information in the same interview with Ashley Dean: “My sister told me about all kinds of water leaks and people on her roof with heavy equipment.”

And from the WAPO article:

Days before the collapse, Stratton, 40, the model and yoga instructor who went silent after calling her husband in Denver, had told family members that “something was wrong” with the building, according to Dean, her older sister. Stratton, who remains among the missing, had seen water damage and worried about the heavy equipment she saw being lifted to the roof for repair work, Dean said.

Other residents had expressed concerns, too. Elaine Sabino, a transplant from New York who had lived in the tower’s penthouse for two years, complained in recent weeks “about the construction on the roof,” said her brother-in-law, Douglas Berdeaux.
Sabino, who is also missing, “said it was vibrating her unit,” he said. “She even went up to talk to the construction manager and told them whatever they were doing was making her rooms vibrate. She said she was worried that the ceiling was going to collapse on top of her bed. She also said she heard water around the elevator. A manager went up to her unit with her and looked around, and told her they’re doing some work, but everything was okay.”

Also, Fiorella Terenzi who lived in Champlain Towers East and who had a clear view to CTS, was quoted in a NYT article, “Ms. Terenzi said she had seen heavy equipment on the roof of the south tower for the past two weeks.”

Out of the many possible causes of the collapse, the prior two weeks of roof work to install the anchors for window washers by drilling into the columns of the building, using what observers identified as “heavy equipment” and creating vibrations in the concrete structure over a two-week period just prior to the collapse, and the account of hearing running water from inside the building and Stratton’s unspecified “water damage,” has to be considered a factor. The work having just been completed, the roof inspection, apparently expedited, had occurred on Wednesday with the building failing only hours later. Could load or vibrations from this roof work have further weakened the columns in the basement in the area of the building that fell first, if the basement columns were already compromised? Remember that vibrations from road work and the load of materials placed on the roadway were factors in the fragile non-redundant-design 35W bridge failure, causing the failure below the bridge deck of the supporting structure. I felt it was a good idea to add this, as some, reading my post, made an assumption that was not correct and jumped to a wrong conclusion. In fact I am not making any hypothesis about the failure but only mentioning possible implications from the survivor’s stories, which also tell us there was indication of a failure / collapse just before the pool deck failure, and perhaps many other earlier subtle signs in the previous days. This would be more likely than not.

I think that we also have to give weight to the statement that Cassondra thought that something was wrong with the building. It is frankly an odd thing to say as she said she loved living there. A very odd thing to bring up in conversation. In addition, from a CNN article,

Pablo Rodriguez, whose mother and grandmother are among at least 99 missing, said his mother called him to report "creaking noises" she heard a day before the building collapsed. 
"She just told me she had woken up around 3 [or] 4 in the morning and had heard like some creaking noises," he told CNN's Erin Burnett. "They were loud enough to wake her."

And from another WAPO article:

“I was telling my mom how this place is great, the house is great, everything is great,” Gabe [Nir] said. “But then slowly, when you live there, you start to notice the small creaks and the small issues the building had.”

There was the water that pooled in the parking garage after rain, he said, and the uneven pool-deck pavement. Sometimes when he stepped on it, water would seep through the cracks.

This suggests that there were signs that something was wrong with the building and that the failure may have started some time before the actual collapse, and that this may have been during the time roof work was occurring. It would be helpful to know what day the roof anchors were installed over the x11 units and if those were done last, as perhaps vibrations might have traveled down through the building at that time to possibly weakened columns in the basement level. Also - the uneven and waterlogged pool deck area that Gabe Nir would have been most likely to have walked on and most often would have been the patio right outside their unit.

2) 611 Maria Iliana Monteagudo

There appeared to be two separate failures that can be deduced from Ms. Monteagudo’s account. The first woke her up but she could not articulate what it was. From a WAPO article:

Monteagudo, 64, was asleep Thursday morning when a strange feeling woke her. “It’s like something supernatural woke me up. I felt something strange…”

She continued:

“…I thought, 'Oh, I forgot to close the sliding door to the balcony, and the wind is making the noise,’ ” she said. “I tried to close the sliding door, and it felt like the building was moving. The door wouldn’t close.”

Then Monteagudo heard a crack. There was a line in the wall coming down from the ceiling — about two fingers wide. “Then it started getting wider and wider as I watched,” she said. “Something said, you have to run. You have to run immediately.”

No kidding. A crack running down the wall getting wider and wider…that would indeed make you want to run. Her account also mentions movement of the building. The x11 units were becoming racked (the window frame out of true) and the wall was actually splitting open. A crack was also heard in the 711 Ring video but the collapse occurred only seconds after that, so this must have been an earlier crack, because she did not leave immediately. Surprisingly she did a number of things then in spite of saying she left immediately, things that must have taken perhaps thirty seconds to one minute before reaching the stairwell, and that must have taken great presence of mind considering the circumstances:

“I ran to my bedroom, and took off my robe and changed into any dress and any sandals. I ran to the dining room table, I got my purse and my credit cards. I took the key, I blew out the candle that I light every night for Guadalupe of Mexico,” she said. “I blew out the candle, just in case.”

What can we conclude from this? That section of the building was beginning to fail. We know the pool deck failed prior to this from the parking garage video. We know there was a short period of time between the pool deck failure and the building failure from the Nir accounts. Ms. Monteagudo’s account continued:

Monteagudo ran to the stairs, descending quickly. Between the sixth and fourth floors, there was a noise — and she realized the building was falling. Monteagudo worried that she would be crushed. “I thought if it’s coming down, and it’s coming down, down, down like a domino effect,” she said. This mirrors the sound from the 711 Ring video of several distinct separate floor failures right at the end.

In a video interview she said that she thought that three seconds had passed between the time she entered the stairwell and the time the building collapsed. If she ran from her unit, perhaps 15 to 30 seconds occurred before she entered the stairwell. She must have been running because she said that she had already gone down at least one flight in three seconds.

Continuing from the article:

When Monteagudo finally escaped from a door, there was water up to her ankles, and cables floating in it. She ran into a security guard. “He told me, ‘Mama, mama, let’s go, this is an earthquake,’ ” Monteagudo said. “I said, ‘No, it’s not an earthquake, it’s the building falling down.’ ”

There was a wall she needed to climb, then an abyss several feet wide. The security guard urged her to jump. “But I couldn’t jump,” she said. “I saw a piece of column, and I put a foot on it, and I climbed over and found myself in the middle of the street.” She emerged from the building in the visitors parking area.

It sounds like she was able to get to the basement, get past the debris at the bottom of the stairwell mentioned in the escape of the Aguero family, and then oddly ran into the security guard. Since there was no egress between the lobby and the stairwell, and the front door locked when the electricity went off, it is not clear how the security guard found a way to get down to the basement to escape. Perhaps the large lobby windows had broken providing an exit down. But it sounds like they both were able to climb debris in the sunken parking garage area in such a way as to climb out in the front of the building rather than to the rear and to the beach as the Aguero family had done. That part of the building, the valet parking, was not enclosed, was open to the elements, so any part of it that fell, and perhaps it fell all the way to the front of the building, could have provided escape along the edges of the valet parking area by climbing upward as she described. Climbing out along the front would have led to the street.

1) 111 Nir family

The Nir family observed three separate failures: an extreme crashing sound in their unit, the pool deck failure outside the lobby, and the building failure, in that order.

Sarah Nir gave extensive a detailed interview to CNN. But several things in that interview immediately stood out as odd or unlikely, which were subsequently contradicted from her childrens’ accounts. Her children’s accounts provided more accurate detail than hers.

The first thing that did not gibe in her account was, “it’s really a wall separating my apartment to the security guy.” The door to unit 111 is located near the end of a corridor and to reach the security guard, in the lobby, she would have had to go down the corridor and then take a left (and apparently, looking at an image of the lobby, then open a swinging privacy door to enter the lobby from this back hall), where the security guard desk was located nearby.

She had described the loud noise that prompted her to go to the lobby and talk to the security guard as, “a smash the wall is collapsing, the wall above me.” From other accounts we learn what her two children heard and experienced at that time and after she left the apartment. In a video interview her 15-year-old daughter Chani said, “I went to take a shower and I came out of the shower dried myself and I was about to get dressed and hear like a big boom and I was like oh no something’s not right and I just ran out of the bathroom and I checked and I thought the whole ceiling was like collapsing.” This must have been as her mother was walking out the door to go to the guard desk, or just after. Significantly, both mother and daughter described the sound as that of something collapsing and the daughter expected to see the entire ceiling had fallen when she came out of the bathroom! From this we can assume it was an extraordinary sound. Both also took the sound to come from above.

The son, 25-year-old Gabe, was in the kitchen. In an article from CBSNews,

…they all arrived back at the building just before 1 a.m., he said. That's when the family started hearing loud noises. Gabe said it sounded like construction…”As soon as she goes down to the front, I hear this loud rumble. Like, you feel like an earthquake is happening right in front of you," he said. 

From The Republic:

Down on the first floor, recent college graduate Gabriel Nir had just finished a late night workout and was in the kitchen cooking salmon. The rest of the family would normally be asleep, but his 15-year-old sister had just returned from babysitting and was in the shower, his dad was out of town and his mom had just come home from an event.
They all heard the first thunderous rumble. They knew the building was undergoing construction and had been irritated by the incessant noise, but this felt different.
Sara Nir, their mother, ran to the lobby, asking the security guard if she’d seen anything.
Back in the kitchen, thick, concrete dust came rushing into their apartment from the patio windows near the pool. The ground was shaking as 25-year-old Gabriel ran to the bathroom.

“We have to go now!” he screamed to his sister. They ran to the lobby,…

From CBSNews:

Gabe told his sister to leave the apartment with him…

So we know that right after Sara Nir left the apartment, her children left for the lobby as well - in a hurry - because the building was rumbling and shaking and concrete dust poured into their apartment from the patio sliding glass doors. This is completely at odds with Sara Nir’s account, in which she runs back to the hallway, looks down, and sees her children were lackadaisically idling by the front door of the apartment where they had to be spurred into action by her to rescue them, as we see from her CNN interview and a WAPO article, below. This is the second inaccuracy in her story.

From the CNN interview:

The minute I say what are you doing about that it is a big boom and I was running to see where the sound come from and I saw all the garage collapse. … I ran back to the hallway and I saw my two kids standing next to the door they’re just in front of my apartment and don’t move. And I was screaming it’s an earthquake an earthquake and I was thinking very fast … So my daughter was looking at me and said but I am with my bathrobe and I said I don’t care run run! run as much as you can.

From the WAPO:
An earthquake, she thought, dashing back toward Unit 111, toward her kids.
Gabe, 25, a night owl, had just pulled salmon from the oven, while 15-year-old Chani was fresh out of the shower. The two stood gaping at their mother from the doorway of the apartment, drawn out by the commotion.

These following two different NBC6 articles indicate that her two children were in the lobby with her when the valet parking and nearby pool deck collapse occurred. Both said that they saw this collapse, which to them was the “second” collapse.

From an NBC6 article: “The first collapse happened, and me and my mom and sister went out," Nir told NBC 6 just hours after Champlain Towers South partially collapsed Thursday morning. "We see the collapse happening on the poolside and I saw a bunch of cars going inside the car garage, so I panicked, my mom panicked, everyone panicked."

From an NBC6 article: “We heard like another boom, while we’re still in the lobby, then we ran outside, and we see the whole pool area is just gone,” said Chani.

The third inaccuracy in Sara Nir’s CNN interview is something that I found hard to believe as soon as I heard it: “the security guy he was shocked he didn’t know what to do I said call the police and he said but what is the address of this building? He didn’t know he was so confused. And I say 8777 and he say no no no write for me and I tell my son write for him and he wrote and we ran out of the building and I told my kids run as fast as you can.”

They have seen the building is collapsing and they are about to run for their life, yet the mother asks her son to oblige her to write down the building address for a security guard that doesn’t know the address and doesn’t understand it when you say it and insists it has to be written down, doesn’t call 911 immediately and doesn’t seem to know what to do in an emergency? This did not happen as she described.

From the WAPO:

Fleeing the faltering building that night, the Nirs yelled at the security guard to call 911. The stunned guard asked for the address, reaching for a pen and paper. “I said, ‘Listen, forget about it,’” Gabe said, and he hurried away.

From The Republic:

…We have to go now!” he screamed to his sister. They ran to the lobby, where their mother urged the security guard to call 911. The guard couldn’t remember the address so Gabriel phoned. “Please hurry, please hurry,” he begged.

So we see that the more realistic scenario occurred, where Gabe phoned in a 911 call himself and they had no time to write down an address.

While in the lobby both children noted that they saw the Argentine actors, a couple. In the Chani CNN interview she says, “We were the first family out and there was like another family they came from the elevator and they’re like you don’t even understand we felt like rumbling inside the elevator.“ In the WAPO article, “As they fled, the Nirs said, they saw a man running to the doors, pushing a stroller. A couple was near the elevators, the woman struck speechless.” This indicates that this couple was aware that something was happening to the building while they were in the elevator going from the basement to the lobby. They emerge from the elevator to an already collapsed pool deck and dust filling the lobby.

Sara Nir’s CNN interview continued:

…I told my kids run as fast as you can. Crossing the street we cross Collins we just cross Collins God watch us God was waiting for us to leave the building. And then another big boom then we didn’t see anything it was suddenly white after the big boom and it was white dust all over and I thought I am by myself in this world. And I thought we were still running and I told my son call the police again call the police again. Probably my son was looking he was very curious to see I didn’t tell them to watch what is going on in the back but probably he looked and he saw the building collapse. But I say it’s an earthquake we don’t know what is safe where the ground is safe run and we still running and running. I couldn’t breathe I couldn’t do anything and I said God help God help and I didn’t know what to do. We had been really running like three four blocks away from the building and then I need to breathe…

In the story from The Republic, it is Gabe Nir who takes action in his account. It seems he ran outside for a minute to get a better view of the collapse of the valet parking area:

Outside, he noticed the car deck had caved into the parking garage. Car alarms were blaring, emergency lights were flashing and water was rapidly filling the garage where pipes had burst.
He ran back to the lobby, where the choking dust cloud was making it difficult to see. Residents from upstairs were running out the door screaming, many still in pajamas, one man pushing a baby stroller.
It was getting harder to breathe. The rumbling intensified, as he pushed his mom and sister safely into the street.
“Run, run,” he ordered.
Tiny rocks and bits of debris pelted his head as he turned back to face the image that still haunts him.
“I saw the building turning into a white dust,” he says.

From the WAPO: They surged out the front entrance and onto a quiet Collins Avenue.
The dust was everywhere, like a sudden sandstorm, burning the Nirs’ eyes and throats. Gabe pulled his shirt to his face. Over a six-minute call, he remembers telling the 911 operator, “You guys need to come here ASAP.”

From an NBC6 article: “It was at that moment I saw the ground shaking. I felt something was happening," Nir said. "At that time, I had to run out. I told my mom, my sister, 'everyone, start running,' and so that happened. Everything started, out of nowhere, like cement, dust, sand coming out."

From an NBC6 article: “We heard like another boom, while we’re still in the lobby, then we ran outside, and we see the whole pool area is just gone,” said Chani. … “So we’re all just running across the street and the second we got across Collins, we hear like a huge boom and we see white dust particles following us, there were like three parts of the collapse, I think that was like the last collapse and I was like, whoa,” said Chani.

From CBSNews:

Gabe told his sister to leave the apartment with him, and when they got to the lobby, they joined their mom and started to run. As Sara and Chani ran from the building, Gabe called 911. 
"I'm on the phone with 911. I see cars going inwards, underneath the building — underneath the building is the car garage. And next to the pool area, you just see everything just sunk down below, underneath. And I hear car alarms going off, I see lights flashing everywhere. And I remember telling 911, 'I can't explain anything right now, you guys have to come here ASAP,'" he said. 
"I remember screaming to my mom and my sister, 'Run, run, just run for your life,'" Gabe said, adding that he heard screaming from others and it felt like a nightmare.
“I didn't know where to run. You couldn't see anything. It was like a sandstorm. Just white, concrete dust," he said. 
The 25-year-old caught up with his mom and sister and they continued to run from the scene. He thought the cause of the collapse was a gas explosion and wanted to get a safe distance away.

So what can we conclude from the Nirs’ accounts? The “first collapse” that they identified was a significant sound that resulted in building movement, rumbling, and most importantly, significant dust, which Gabe thought was concrete dust, quickly entering the apartment from the patio door area. Both the mother and daughter said the sound came from above. All three say they previously heard “construction” noises. In the six months they had lived there, perhaps they had been exposed to construction noises from renovations in nearby units. Perhaps they were referring to the recent two weeks of construction on the roof of the building. We can conclude this could have been one of a number of things. First it literally could have been late night construction occurring in unit 211 or another nearby unit above them that resulted in a collapse. Secondly it could have been the first significant step of the imminent building collapse and it may have only sounded like it came from above. Third, it could have been that the first portion of the pool deck to collapse was right outside their patio doors.

We know that the “second” collapse they describe, the collapse of the valet parking and the part of the pool deck that was adjacent, came fairly quickly after the first. We know this because Sara Nir had only just begun to talk to the guard about the noises and her children who had rushed out of the unit just after her also witnessed this.

We also know that the building collapse - the “third collapse” in their account - came fairly soon after the pool deck collapse, both from Cassondra Stratton’s phone conversation with her husband and from the Nirs’ accounts.

From the Monteagudo account we know the x11 units were coming apart shortly before the building collapse and that Gabe Nir felt movement - shaking - in unit 111 before leaving.

Witness statements are notoriously inaccurate. What is reported in the media is rarely what the person actually said, and then you have translation issues on top. I don't believe any forensic analysis relies on them. The answers are obtained by close inspection of the rubble, which is why samples have been taken for analysis. Courts of law may rely on witness evidence, but engineering is done with measurement and numbers.

I am open to the idea of roof-first collapse, it is a valid possibility, but still have seen no evidence for it. The security video that shows the collapse does not show the penthouse collapsed, but the whole building collapsing. At least without the first frames (which indeed are missing), the video is not definitive and can be (and is) interpreted both ways. The roof-first theory also requires a longer sequence of coincidental events. The garage collapse theory only requires chronic fatigue of garage level columns, and given the evidence of water encroachment into the basement, remains the simplest and most likely theory.

Quote (Tropmet)

There has been a lot of telephone game and paraphrasing of witness statements both in the media and on this thread - but because they were on the spot what they saw and experienced is extremely important and needs to be accurately documented.

For example:

Quote (Tropmet)

First, Cassondra was on her balcony (which afforded a clear view of the pool deck) at 1:30am, upset, and calling her husband in D.C, waking him up.

It seems pretty conclusive that the building had collapsed by then.

Not saying it wasn’t reported the way you’ve portrayed it. But supporting links back to those sources would have been helpful.

I was going over some of the NIST photos and found a few things of interest:

It looks to me like this was a pool slab with original tile on the right and a planter on the left. Look at the concrete deterioration under where the planter would have been.



This one shows another piece of slab. I am assuming that the rebar loops are beam stirrups and that this slab may have been at a slab step. What bothers me is how clean the 'fracture' is. This looks more like a crack that propagated over time than something that happened suddenly. If they are beam stirrups, the beam must have just turned to rubble.



Possible punch shear and more bad concrete under a planter?



I don't like the dark gray surface where the floor connection would have been. Again, this looks like something that was like this for awhile, not a sudden fracture.



Any thoughts?

Microwizard thanks for pointing out that time, that was from a Miami Herald article and I will remove that reference to the time.

Regarding accuracy, that is why I have grouped corroborating quotes together.

I do think there is quite a lot to be learned from witness statements to the press (probably the interviews with NIST would be much more detailed and eventually we will get to read them) and they should not be dismissed wholesale as unreliable, especially as my focus was not on a quantitative timeline so much as comparing what was experienced and seen. For instance, I would not expect Mr. Stratton to forget his last words with his wife, and I found it telling that scattered among different news articles both Nir siblings had similar observations and timelines.

It was news to me that Gabe Nir saw dust coming into 111 from the patio doors, as that was only noted in an AP article and not in the WAPO article. I have tremendous respect for the AP. This is an important bit of information and was not noted on this forum prior or in any other news article.

Quote (MikeJ65)

I don't think any slab with remnants of tile and grout lines like that would be from the pool deck. The pool deck slab had a waterproofing layer, a layer of sand, then pavers (and maybe other layers), but not tile that was attached directly to the slab.

In fact, the second-to-last photo looks like a balcony slab to me. The corner seems to be curved just like the balconies, and again, the evidence of tile on the slab would be more consistent with a balcony (or perhaps an interior floor). But the curve to me is a big indicator that this was a balcony slab.

@Tropmet... excellent summary.

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

-Dik

Quote (MaudSTL)

This is incorrect. They did not see the garage ceiling collapse. Instead, they heard a loud noise while swimming in the pool, got out and went over, and then saw rubble and a gushing pipe in the garage entrance. Adriana Sarmiento started videoing at 1:18 am.

At best it's ambiguous. The husband of the tiktoker was interviewed and said "The first thing that we saw was something fall down". His gesturing was as though some slab or ceiling came down. The reporter preluded by explaining that Castilero "saw the ceiling of the first floor of the Champlain tower cave in".

This interview was on June 24 before the tiktok video went public and the theory of the patio slab preceding the collapse went mainstream.

Starts at 1:16 https://www.youtube.com/watch?v=BvkRmtmB-Fw&t=...

Quote (MikeJ65)

Possible punch shear and more bad concrete under a planter? Any thoughts?

Link
This is the same chunk featured in the first photo from this post. It's number 9 with a number 12 near it. If it's from a balcony I would guess the hole was cut in it to facilitate lifting.

[quote microwizard (Computer)19 Jul 21 16:59 Witness statements are notoriously inaccurate. What is reported in the media is rarely what the person actually said, and then you have translation issues on top. I don't believe any forensic analysis relies on them. The answers are obtained by close inspection of the rubble, which is why samples have been taken for analysis. Courts of law may rely on witness evidence, but engineering is done with measurement and numbers. I am open to the idea of roof-first collapse, it is a valid possibility, but still have seen no evidence for it. The security video that shows the collapse does not show the penthouse collapsed, but the whole building collapsing. At least without the first frames (which indeed are missing), the video is not definitive and can be (and is) interpreted both ways. The roof-first theory also requires a longer sequence of coincidental events. The garage collapse theory only requires chronic fatigue of garage level columns, and given the evidence of water encroachment into the basement, remains the simplest and most likely theory.][/quote

At this point it’s pretty clear that the collapse of the building was preceded by the collapse of the pool deck. As to whether the pool deck failed spontaneously or it’s failure was caused by something falling from the roof is very much an open question. I don’t know why people seem to be certain of one or the other of these scenarios as they are both plausible and supported by plenty of circumstantial evidence. I look at the first second of the surveillance video which seems to show a missing section of the parapet along the roofline prior to the main collapse. We know from the plans that the parapet connection to the roof deck was very weak and it wouldn’t take much to knock it off the roof. As to the spontaneous punching shear failure, I’m less certain. I’ve inspected, analyzed, and designed reinforced concrete structures in coastal areas for more than 20 years and what I’ve seen is that usually a failure like what happened with the pool deck would be preceded many days of heavy, noticeable, cracking and abnormal deflections. Another thing that my experience has shown is that usually in these cases the original flawed design is a major contributing factor. I looked at the plans early on and found at least half a dozen mistakes.

We’ve been following the same research path to try to understand what the witnesses heard and saw. My goal has been to create a timeline that sequences what witnesses experienced.

Many media outlets are paraphrasing the source interviews and we should interpret all of these secondary pieces, not just the NY Post, with a grain of salt.

• Human beings who have survived a trauma generally recall important elements or snapshots until they have had time to piece together a narrative in their own minds. So the earliest survivor interviews are more like snapshots, and the later interviews are more narrative, and include additional details, like the dust, from secondary recall.
• Everybody is the star of their own show, with each personal narrative overlaid on their personal snapshots. So we also need to consider whose POV we extract meaningful information from, and also whether they’ve had time to commiserate with the members of their cohort to develop a cohesive group memory. The Nirs are a cohort of three, Nico Vazquez is a cohort of two, and Ileana Monteagudo is stand-alone.
• In the case of the Nirs, we also need to consider that they have been the most interviewed, and media narratives have developed around Hero Mom and Hero Son, which can obscure the hard, building-related details that would help this group’s inquiries.
• In the case of Cassondra Stratton, we currently have no time stamp and only a third hand (Ms. Stratton >> Michael Stratton >> sister) account of what she said. I think we need to wait for more direct information from Michael Stratton to get the greatest value from Ms. Stratton’s final moments in 410.
• Every single survivor is speaking English as a second language. So we have to be careful about judging the accuracy of word choices. Sometimes people can’t find the right word, especially in a second language. It stands to reason that they will find better words to describe their experience after they’ve had time to process the trauma. This places great value on good translations of direct interviews in the survivors’ first languages, Hebrew and Spanish.

Among the primary source interviews with the Nirs in 111 are Jeff Franco (Gabe,) CNN (Sarah and Chani,) WaPo Sarah and Gabe,) and Channel 13 in Israel (Gabe,) which is reported on by the Times of Israel. I think the Israeli Channel 13 interview is important, because Gabe had had time to process his experience and he would have been speaking in his first language, Hebrew. I am planning to see if my Israeli friend can find the Channel 13 interview and help us get an accurate translation. One thing to keep in mind about Sara Nir’s statements is that, unlike Gabe or Chani, she was looking at her computer/phone during the first collapse, so she has the most accurate time sense at that point. She has been consistent over multiple interviews that the first collapse (crashing wall from above) happened at 1:10. The WaPo reports that she put down her phone to go to the lobby at 1:14, which a lot of secondary sources have mistakenly picked up as the time she heard the first collapse.

The primary source interview we have so far with Nico Vazquez in the garage and lobby is his Spanish WhatsApp statement, which he made on return to Argentina. So by that time he and Gimena Accardi had had time to process individually and as a cohort with a shared experience.

The primary sources for Ileana Monteagudo in 611 are her WaPo interview in English and her Telemundo interview in Spanish. I wish we had a good translation of the Telemundo interview because we might be able to figure out exactly which wall the crack was in. Ms. Monteagudo gestures to her right when she describes it, but we don’t know which way she was standing at the time she saw the crack chasing down the wall…back to balcony or facing balcony?

Edit the more I look at the image below, the more it looks like the rough raised area is part of the slab step down, and this is where the first patio was outside 111. It may have had tile in that area next to wall, as that was unit 111’s private patio area.

Or more likely from 211 floor and cantilever above? I think it has been posted there were beams between floor 1 and 2?

Edit 2: The crack Sara Nir saw could have been the outside wall peeling away from inside walls as column buckled between Unit 111 and 211.


I keep saying to myself, I will not do another post, but then Tropment makes an excellent post, and then the photo below is posted.

Here is what I see in the photo with my 'Vintage Peepers'

I believe this is a cantilever slab coupled with some of the slab from inside a condo unit. The red arrow points to a rebar like you would have if this happen to be a cantilever with a poorly tied parapet wall sitting on it. Or perhaps this slab had a masonry wall sitting ontop of it where the rebar is?

The green arrow points to where the slab cracked between possibly a condo wall/column line and the outside cantilever deck. It looks like thickset maybe was floated on the inside portion of the slab fragment.

I too think the grout lines indicate cantilever that had tiles mortared/adhesive bonded directly to top of slab with no water proofing layer in between.

I also think thickness based upon the other pictures is around the 6-8" mark vs the 9.5" patio slab.

I also see the bottom rebar appear to end at this fracture point, and not be continuous thru this possible joint or to termination say into an unreinforced CMU wall?

Edit: If you zoom in close, it appears there is one top rebar showing above the bottom rebar, so perhaps a column line at the crack and the rebar is a column tie on top of slab?

Edit 2: The holes at the curved portion in the other picture look like where handrails were inserted into slab...

Quote (MaudSTL)

Here is my translation of Ileana Monteagudo's first interview. She indicates clearly where she saw the crack (the wall near the balcony door) coming from the roof, downwards. Her first interview was not with telemundo but AmericanTeve41, a local station while still at the Surfside victim center. I tried to keep the grammatical structure and order as similar as possible, not necessarily how an English speaker would say it, unless it would change the message being conveyed. I kept most of the filler words, and's, and run-on sentences as spoken. I indicated where Spanish idioms were translated into their equivalent.

https://www.youtube.com/watch?v=Dggm2FTyn9k


I was asleep and a supernatural force awoke me, that there was a bad ambiance [ambiente enardecido] in the apartment.

and I heard some strange sounds and I thought I had left the door of the balcony open. And when I went to the living room, indeed, the living room door was open, the one facing the ocean, the balcony.

I tried to close it and I could not. It appeared that the rail of the door had disleveled. ["y no pude. Parece que se habia de disnivelado el riel"]

And I hear another crack and when I heard that crack, I looked at the wall, I see a crack ["grieta"] coming down from the roof to the floor, of two inches in width.

Something told me this is going to fall.

I ran to the room, I removed my sleeping clothes, I put on a dress with some sandles. I went to the dining room and grabbed a purse with my ID and credit cards, pills, keys and my neckalace which I had taken off. I turned off the Virgin's candle. And just in case (Spanish saying "por si las moscas") I closed [or locked. Ambiguous] the door.

I did not know where the emergency stairs were. I went to the elevator which was much farther. I did not know that I had two emergency stairs next to my apartment. If I had known that there were two stairs next to my apartment I would have gone through there thinking that they would be faster.

Well, in the far stairs, as I arrived at the 4th floor, coming from the 6 to the 4th, I hear such an infernal noise, that I knew that part of the building had collapsed.

I saw the security guard, skinny like this (raising her finger), a kid, who said "there was an earthquake! there was an earthquake!", and I told him no this isn't, THIS building collapsed.

I scraped my legs, but I arrived to the level that I needed to be at. Later there was an enormous gap that I needed to jump over. One obstacle more to get to the street.

And I couldn't but god placed an obstruction that served me as a step. I put my foot on that step with my left leg and with my right leg I was able to reach over to firm ground.

Quote (Tropmet)

I found it telling that scattered among different news articles both Nir siblings had similar observations and timelines.

If they are accurate, then why aren't they identical? If they are different, whose version is correct? Even if one witness is 100% correct in all their observations, there is no way to tell which one. Hearing is an even worse sense than sight, it can be very hard to tell exactly which direction noises are coming from.

Did any witness say they *saw* something, anything, falling from the roof? If not, there is no reason to think anything did.

But we are asked to believe something on the roof suddenly decided to lurch sideways, knock out the parapet, which then coincidentally lands on the weak patio, initiating collapse at the garage level. This is magic bullet stuff!

Or the garage level collapsed.

Which is more likely?

NIST are analysing concrete and rebar. They are not asking witnesses "so, where do you think the collapse started?"

Quote (MaudSTL)

The primary source interview we have so far with Nico Vazquez in the garage and lobby is his Spanish WhatsApp statement, which he made on return to Argentina. So by that time he and Gimena Accardi had had time to process individually and as a cohort with a shared experience.

The earliest publications that I could find which refer to that voice message are dated June 24th so I'm not sure they had time to return to Argentina and process much yet. Other than that, your timeline is really useful for trying to piece together the sequence of events as these people experienced them. Thanks for putting it together (you, and Tropmet for scanning and comparing the various statements).

I would hope Miami-Dade Police and the Judicial Branch are investigating the Crime Scene to include Witness Testimony and not NIST directly.

I would also expect NIST is focused on gathering the physical data from the collapse to populate their models with.

Bottom Line, they both have a role and should be focused on their respective piece of the puzzle.

I see both groups gathering the facts and evidence without being closed minded as to what was the trigger.

They both have their lanes, one is from a legal perspective and the other is from an Engineering perspective..

Quote (I would hope Miami-Dade Police and the Judicial Branch are investigating the Crime Scene to include Witness Testimony and not NIST directly.)

and they should investigate the reasons for toppling the rest of the building to see if there are any other reasons than safety...

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

-Dik

In reading the back-and-forth here for days it seems to me that the early roof vs non-roof debate has created a binary distinction that is coloring later discussion. The various witness statements of noises "above" does not mean "on the roof" necessarily, and even problems originating on or near the roof does not necessarily imply a claim that the roof collapsed first. Strain in the fabric of the building could be bringing down ceilings in apartments all over, and the distribution of noise and vibration through the columns has been mentioned several times. "Above" is a relative term.

While also I think it's possible that resident stories of heavy machinery, vibrations etc on the roof are shaded by perception and their dislike of disturbance to their homes, but would we really be shocked if it turned out the roof work was one more non-trivial insult to a terminally weakened structure? It does not need the roof to have collapsed first for this to be true.

Quote (dik)

and they should investigate the reasons for toppling the rest of the building to see if there are any other reasons than safety...

Like what? To protect the structural engineering firm that had been contracted for more than $500,000 to analyze the structure and design repairs?

Ausg, Yes, IMO the hammer drilling and activity on the roof was just the near final vibration induced event that may have started slab or beams to collapse due to shaking of tired under nourished and neglected structural joints.

Perhaps the rain was the final blow to an already weakened structure due to corrosion, chemical changes in soaked concrete and loose joints from N-S racking movements from vibrations next door and 3.9 after shock.

She was definitely appeared to be ready to go any minute

Quote (MaudSTL (Computer))

.. and Channel 13 in Israel (Gabe,) which is reported on by the Times of Israel. I think the Israeli Channel 13 interview is important, because Gabe had had time to process his experience and he would have been speaking in his first language, Hebrew.

You make excellent points about snapshot/narrative and cohorts, though to me it's clear Gabe and Chani are English native. Only their mother isn't. Times of Israel is a news aggregator; sometimes editors at such sites will add their own spin... but their primary source could as well have been Channel 13 Tampa (Fox) or Orlando (Spectrum/radio).

Probably the most "snapshot" source is the 911 recordings (https://www.youtube.com/watch?v=gXGIWSkfW1s). At 01:16:27 the first call comes in, a woman with a confusing accent reporting a big explosion, which she corrects to an earthquake - that seems to be the security guard relaying Sara Nir, who never grabs her phone but would have felt the ground slab shake from the plaza collapse. At 01:16:39 the alarm company notifies the police - so it would seem the silent alarm tripped on the garage after all. At 01:21:57 Gabe Nir calls, and by this time he's on Collins Ave. as we hear a Miami-Dade employee confused about the address. The loud rumble of the full building collapse is audible at 01:22:20 +/- 1s if the 911 tones are accurate in time. That's over 5.5 minutes between plaza and building collapses, meaning there was plenty of witness time lost to confusion/standing around as opposed to full-on panic.

As for the Argentinian actors, I've found almost zero primary source detail; pretty much the only good account I had to get from translating a news article: https://www.infobae.com/teleshow/2021/06/24/gimena... It seems one or both of them heard a strange "creak" before entering the elevator, then the actual plaza collapse happened while they were inside. The rest basically says they didn't escape as aggressively as the Nirs, perhaps stopping to help others.

@Thermopile
@MikeJ65

If I am not mistaken, that balcony slab belongs to unit 511.

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

@Demented, The balcony slab in the picture (number 9 marking) sure looks like it could come from Unit 511. The 511 living area tile/marble floor is a lot higher than the tile floor on the balcony, and the slab #9 shows cracking under the exterior wall/sliding door.

And I too see the signs of sagging slab at sliding door. At top and bottom.

And back to double front door, I now think the right side wall is no longer parallel to the left side, thus racked and perhaps sloping floor too.

Right door may have been cut off at bottom, so it would not drag due to racking of jamb wall. Look at tapered gap between active panels.

The marble floor cracks and slopes do not look right either, and look like they are sloping towards sliding door/outside wall....

I don't remember how long ago was the renovation of 511, but they sure added lots of weight to that floor slab!

Could 511 be first building slab failure? Definitely it is on the list, IMO.

Edit: Was 511 renovation after 2018 Morabito report? How much individual unit renovation was done between 2018 and 2020 when Morabito got back involved, and sounded a stronger alert this time.

Edit2: The construction next door causing shaking of building was after 2018 Morabito report, and finishing up probably around the 2020 timeframe. So how much of a contributing factor was the pile driving, especially sheet piles within 10 feet of building...

Quote (but would we really be shocked if it turned out the roof work was one more non-trivial insult to a terminally weakened structure? It does not need the roof to have collapsed first for this to be true.)

Well this seems like a very reasonable comment to make, but the truth is that there was nothing in the 2018 report that would indicate that the building was “terminally weakened” and going to collapse 3 years later. None of the issues that were noted were anywhere near the level of deterioration that would cause any structural engineer to say the building was unsafe for occupancy. People need to understand that structural engineering isn’t just about creating a structure that will carry the loads, but is also about designing such that if failure occurs, it happens in a ductile, progressing manner that reduces or eliminates loss of life. The biggest mystery to solve in all this is why there were not more warning signs.

Unit 511 sold on 5/5/21. So was renovation done specifically to hide the defects in the floor so unit could be flipped at a nice price?

All I found on Surfside Permits was Unit 511 got a new Rheem AC in 2019, with hurricane rated tie down straps.....

Unit 711 just got a Permit before collapse for new tiles..... Hmmmm.....

Unit 711 just got 6 new windows and storm rated sliding door in 2020.....

Boy we sure have a trend going here, and I know Demented already knows all this.......

Unit 211 and 311 both getting or got new AC's

unit 211 gets $76K renovation in 2015 including new floor, new kitchen cabinets, new plumbing fixtures, etc....

Thermopile… can you find any pics of their home theater setups? Maybe they had some big speakers and subwoofers. That’s more load, plus more vibrations. Perhaps someone was using them to try to set up some sort of harmonic to bring the building down? Hmmmmmm… ……… … —- …

@Spartan5, that was a low blow!

@thermopile
Unpermitted bathroom renovations were done recently (Feb/March 2021ish), but it appears that the marble floor has been in that unit for some considerable time. There's a renovation on record with no details in 1981, but I'm still having no luck finding anything in regards to when work was done. The kitchen was possibly done some time in 2003, which would be my guess for when the marble flooring would have been installed. I'm sure internal emails will show if there were any noise complaints related to construction inside this unit.

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

[quote microwizard][
I am open to the idea of roof-first collapse, it is a valid possibility but still have seen no evidence for it. The security video that shows the collapse does not show the penthouse collapsed, but the whole building collapsing. At least without the first frames (which indeed are missing), the video is not definitive and can be (and is) interpreted both ways. The roof-first theory also requires a longer sequence of coincidental events. The garage collapse theory only requires chronic fatigue of garage level columns, and given the evidence of water encroachment into the basement, remains the simplest and most likely theory./quote]

Microwizard, I will have to challenge your quote for contrast but I do so respectfully and with an open mind as well. I am going to make a few points on here then let it be and let time tell what we all have spent hours trying to conclude.

Before I stumbled onto this thread, I had my own preliminary theories on the “core” trigger point due to a trajectory of poor decisions and almost laziness to act on extensively documented structural deterioration, avoiding the intentional act to ensure that this building was even safe for occupants to live in. And I still feel firm in knowing that the “core” priority of immediate construction needed to actually be focused on the “core” of the building itself. The foundation, the structures where, at its core, was screaming through years of water damage, evidence, and recent conclusion that the lower pool area/parking deck concrete, reshoring, and reinforcement MUST be first and foremost focused on and invested in NOW. And the simple fact that during the board meeting focus was actually being honed in on the ROOF first, which for reiteration of “simple”, also heeded the lack of guidance that with all the evidence of concrete deterioration and warnings of structural integrity, guidance and enforcement of ensuring the fundamental strength and integrity of the foundation and “core” MUST be completed FIRST before any consideration above thereof.

And making the executive decision to work on the roof as a top priority was the initiating event that continued feeding the history of “putting lipstick on a pig” except more like “putting more Jenga blocks on top.”

I digress.

I will make my 4 points now.

1) We only tangibly have few “witness” accounts from those who lived deeper in Champlain South, and unfortunately, we will never be able to hear more about the experiences of those who lived on higher floors. But the few accounts given seemed that the residents were very stoic and matter of fact - Not given in sheer panic due to the aftermath of a crisis situation, but more so given in firm and clear communication about the integrity of the building as a result of the recent roof work ensuing with a common concern about the present and future of the building in what seemed to be a “duty to warn”.
-” Fiorella Terenzi who lived in Champlain Towers East and who had a clear view to CTS, was quoted in an NYT article, “Ms. Terenzi said she had seen heavy equipment on the roof of the south tower for the past two weeks.”
- Pablo Rodriguez, said his mother called him to report "creaking noises" she heard a day before the building collapsed.
- Douglas Berdeaux gave an account of how Sabino was very concerned about the roof construction and “said it was vibrating her unit”. “She even went up to talk to the construction manager and told them whatever they were doing was making her rooms vibrate. She said she was worried that the ceiling was going to collapse on top of her bed. She also said she heard water around the elevator. A manager went up to her unit with her and looked around, and told her they’re doing some work, but everything was okay.”
-There was also significant water damage on the roof, right above the failed column in the garage, and Sabino clearly heard water around the elevator to the extent of where she knew it was substantial enough to report, and from there not being corrected or alerted for it doesn’t seem like it was a “normal” event to be occurring at the time.
Roof results of significant water damage documented:


2) Crashing was reported initially as being from above - if individuals attested for crashing coming from above, wall cracking coming from above, it was probably coming from above. Now talk about simple conclusions. (Quote: In a video interview her 15-year-old daughter Chani said, “I went to take a shower and I came out of the shower dried myself and I was about to get dressed and hear like a big boom and I was like oh no something’s not right and I just ran out of the bathroom and I checked and I thought the whole ceiling was like collapsing.” )
The wall appears to have been torn at an angle of destruction, given the triangle hole, and restating from a post a few weeks back, a cantilever and/or balcony area could have actually torn away from that spot, given a roof anchor was just test loaded :




Ironically, a roof anchor crashed into the still-standing adjacent 8th-floor hallway wall which indicates that the "roofing event" dislodged from above could have stayed almost flush to collapsing straight down into that nook along the wall - hitting the compromised pool deck - but again, the initial boom event was probably not watched due to the time of day. And unfortunately, those who may have seen the roof event and have the answers were not able to make it out in time.


3) The building collapsed the day after the roof anchor permit was given to test load. The building had structural issues deep within its core of stability, and the many years of deterioration and what seems like an extensive and progressive weight being added to each floor (heavier cars, marble here, marble there (see link to the penthouse photos) wood, stainless steel appliances with grandiose furniture, heavier HVAC units and recent work) which over time due to the increase in occupants’ “heavier lifestyle” paired with the systemic digression of structural integrity, the building finally gave in and the roof work and load testing was the straw that finally broke the building’s back. Simple facts.


4) Now for my conclusion, I believe the parking deck failure event and roof failure event HAPPENED AT THE SAME TIME. Instead of either/or, its a contiguous and.

From the initial crashing sound as a warning of what was to come, it was only a short matter of time this almost 40-year old building could "hold on" and displace weight without adequate rebar steel reinforcement & sheer wall support.

And im out. Thanks for reading if you made it this far!

Quote (Thermopile)

Unit 511 sold on 5/5/21. So was renovation done specifically to hide the defects in the floor so unit could be flipped at a nice price?

All I found on Surfside Permits was Unit 511 got a new Rheem AC in 2019, with hurricane rated tie down straps.....

Unit 711 just got a Permit before collapse for new tiles..... Hmmmm.....

Unit 711 just got 6 new windows and storm rated sliding door in 2020.....

Boy we sure have a trend going here, and I know Demented already knows all this.......

Unit 211 and 311 both getting or got new AC's

unit 211 gets $76K renovation in 2015 including new floor, new kitchen cabinets, new plumbing fixtures, etc....

It's not just up and down this building. It's up and down this coastline.

We don't engineer things, we over engineer things. And by over engineer, we go up in size 2x on everything to make doubly sure that it's strong enough. More gravity means more gooder.
Why of why did I leave aerospace for the south Florida structural scene...

As far as your speculation on new renovations hiding damage to increase the price to flip it, possibly. That is the norm these days. Home Depot will do everything for you, from permit to install. No inspections required because it's all assumed to be engineered.



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

To be added to all new condo sales contracts:

"If you remodel, you cannot add any weight, as it will make the building fall down."

Might want to add in something about heavy furniture, too. And maybe no overweight people.


spsalso

@Spalso

Last year I viewed two condo units where there were restrictions on furniture weight.

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

Quote (tmwaits1)

You raise an excellent point. I was mainly trying to steer away from roof vs nonroof wrangling. The issue of "once collapsing, why so catastrophically?" is a more useful line of inquiry for future public safety. A question though re Morabito in 2018. I read his report, i.e. significant but reversible problems now but with exponential deterioration predictable, as being as close to predicting an impending terminal state as could be expected without seeing broken structural elements in plain view. Would you see it that way?

So the roof anchor permit is dated June 23, 2021 and the condo collapsed at approximately 1:20am +/- on June 24, 2021, less than 24 hours after the permit was issued. My experience with permits is generally the contractor doesn't schedule the work until they have the permit in hand, because sometimes there are unknowns on when you'll actually get it once you apply. Is there evidence that the contractor mobilized to the project and installed these anchors before the collapse?

So many seem to conflate temporal proximity with causation. Anchor load testing is not column load. It's tying two roof points with a chain hoist, thereby compressing roof slab laterally. If it doesn't crack then, it's really hard to believe it would crack with no load that very night. Anchors are like 45 lbs a piece. The real stress of re-roofing comes from the size of crew doing it. All that vibrating equipment to remove old asphalt, all that old/new material being wheeled around for crane access can certainly cause structural damage if not managed well - that work reportedly happened late May into June.

This one's not structurally important but gets on my nerves:

Quote (JAKLED (Electrical))

Ironically, a roof anchor crashed into the still-standing adjacent 8th-floor hallway wall

• https://files.engineering.com/getfile.aspx?folder=626b5978-38db-45fd-8bc8-1

I guess at this point you might consider it hard to sell 40 year old condo's?

Perhaps there should be some form of retirement assistance for old buildings like this? Get rid of them.

Can someone please explain how those roof anchors were intended to be used? You could not work on the exterior with a safety line or worse an abseiling line tied off at the roof and going over a rough parapet of unknown competence and at those angles. It seems unthinkable.

The anchors are for fall arrest and have to be strong enough to resist a load of 5000 lbs (22 kN).

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

-Dik

AusG

Based on 30 years in Metal Building Structures, where we install those type of personnel tie-off anchors, they are used to work near the edge of the roof, say approximately 10' wide zone all around the roof. Not for suspension work over the edge of roof. One Anchor One person, maybe two persons tied off. Simply fall protection tie-off.


Jim

Quote (dik (Structural)20 Jul 21 06:34

The anchors are for fall arrest and have to be strong enough to resist a load of 5000 lbs (22 kN).)

Sure, I get how the bolts work. it's what happens to the line you tie to it I don't get. The lack of a clear path for the rope or cable or whatever.

Edited: ah OK, Jimstructures, thanks that's clear. They had previously been discussed in terms of high access work over the side, cages and the like.

??

Quote (Demented)

https://res.cloudinary.com/engineering-com/image/u...
"It appears this would have been by the lobby entrance area, on top of the deck? 2 ton tar tank (~800-900psf if left full for next morning as is typical of the area). This wouldn't have been parked under ground in the garage would it have been?"

The position of that Camry appears to be out of place. Possibly due to the rush to remove debris from the collapse site? In the parking garage video from last year, it was parked here:

Quote (CE2537)

So the roof anchor permit is dated June 23, 2021 and the condo collapsed at approximately 1:20am +/- on June 24, 2021, less than 24 hours after the permit was issued. My experience with permits is generally the contractor doesn't schedule the work until they have the permit in hand, because sometimes there are unknowns on when you'll actually get it once you apply. Is there evidence that the contractor mobilized to the project and installed these anchors before the collapse?

So you're saying that they managed to cut down to the slab and mount a couple dozens of roof anchors all on the same day they got the permit?

JAKLED:

I'm not sure what your latest screenshot is supposed to be highlighting. Are you trying to suggest a roof anchor has fallen through the top right of the ceiling? That's clearly some HVAC ducting in my opinion and not at all related to the roof anchor. Presumably ripped through the ceiling as the remainder of the building collapsed taking the HVAC continuation with it.

The numerous posts about x" of tile added being somehow relevant to the building collapse seems to be a complete red herring. Even if the design dead load was exceeded, the total design load would have to be reached to get anywhere near collapsing a beam or floor. It would take 6" of normal weight concrete=75psf on the entire floor to roughly equal a minimum 40psf live load X the 1.7 live load factor. It would seem that at least 50% of the units above would have to had 6" of concrete added to their floors in order to collapse a properly designed column. To presume that remodeling one, two, 3, or even all 13 units had any (substantial) impact on building performance seems just a bit ... illogical.

Quote (RandomTaskkk)

I'm not sure what your latest screenshot is supposed to be highlighting. Are you trying to suggest a roof anchor has fallen through the top right of the ceiling? That's clearly some HVAC ducting in my opinion and not at all related to the roof anchor. Presumably ripped through the ceiling as the remainder of the building collapsed taking the HVAC continuation with it.

I agree. There's nothing that looks like a roof anchor there. That section of corridor (NW corner) has HVAC ducts above a dropped ceiling. It's associated with the large common areas HVAC plant on the roof, with vertical supply and return ducts adjacent to the elevators. The fall of the north wing included part of the same ducts, so they are sheared off at the ragged edge with everything else.

It would be a billion-to-one magic bullet scenario for a roof anchor to end up in the middle of that corridor, in my opinion. There's a considerable volume of solid material between the roof anchors and the central corridor. Also the general momentum of debris would have been away from the remaining building at the 8th floor; it's well above the top of the pile that deflected some material back to the west.

In an ideal world, yeah, but how does it all affect a building with obvious signs of concrete deterioration and a lack of steel reinforcement?
Just adding more weight to the overall picture.
Normally a few inches of rain pooling up in Florida wont be an issue either, but that likely was a contributing factor in the days leading up as well.
Possible data showing the building, and not adjacent properties, has been sinking into the earth since the 1990's.
This is reclaimed wetland.
Multiple copies of drawings floating around, some with revisions to the piles done months before construction, some without those revisions, some with revisions but construction notes specifically stating to ignore the revisions and make the piles 14"x14" precast. *shrugs*
As drawn and as built as it seems has been quite different


While not the reason of why a floor, or the building, collapsed, in my honest opinion, it's pretty illogical to discount a few hundred extra tons of load on an entire, but highly concentrated area.


Edit: @hochhaul
Those images turned out to be irrelevant it seems. It appears it can be inferred from the emails over the smell and the location of the maintenance parking spot that these items were likely on ground level before and at the time of the collapse. I was also looking at the image thinking I was at an incorrect point. I failed to notice the ramp was sloping down and away from image point, not up and away from image point.

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

Quote (1503-44)

To presume that remodeling one, two, 3, or even all 13 units had any (substantial) impact on building performance seems just a bit ... illogical.

I'm inclined to agree with that, but I don't think it can be discounted from a more holistic analysis. If we combine the reduced margin from that extra weight with everything else, it could be a contributing factor. Perhaps the column damage in the middle of the 9.1 row would have taken longer to hit total failure, or even survived, if there wasn't so much extra weight bearing down on the damaged columns.

Two of the most important questions are why the pool deck brought the tower down, and why it progressed so quickly from first major sign to full collapse. That weight could possibly be a quite significant part of the equation, along with the general structural deterioration.

Thinking out loud more than anything here (this is not my industry) and just testing my thought process.

If we assume one of the lower columns failed first, how would the remaining building react to load redistribution?

My assumption is that the upper floors/beams/columns will not be as highly utilised as the lower floors/beams/columns. This should mean they will have more capacity to accept load redistribution as the building reacts to the loss of the column and tries to find equilibrium. Seen as the upper elements are now being loaded to say 100% capacity (from say only 25% previously [notional numbers here just to illustrate the point]), whereas any lower elements also experiencing redistribution are being loaded to say 100% capacity (from say 90% previously), it would stand to reason more distress may be noticed at the higher levels due to the much greater change in utilisation from 'as is' to 'redistributed' loads.

Does this perhaps go some way to helping explain why many of the witness accounts felt like the noises were coming from above? There was simply more capacity, and a higher change in utilisation (therefore cracking etc.), occurring in the upper floors first?

Speaking of roof anchors, could this be a roof anchor attached on the PH-A balcony? I have not a clue as to what else it could possibly be, why it's still there, and what is was doing there in the first place.


Original since potato cam upload.
https://pbs.twimg.com/media/E40BC6BX0AM_jnu?format...

Not the newest of images. This unit was just sold 05/11/21.


Edit: Core drill for railing with odd rusting stains being blurred and sharpened by cell phone camera? It appears to be protruding up rather than going down in.

Murphy9000, My 6" concrete is way over the top. I did reduce it by 50% for multiple floor considerations. I'm saying in effect realistically that additional dead loading of an inch or two of marble in two units or so is a red herring. Of course one pound might have been the straw that broke the camel, but in general excess floor loads is not likely to lead to building collapse.

Random, If the basement column failed, I feel that you don't have to consider how the entire building reacted to load redistribution. You probably don't have to consider any more possible redistribution of load in more than the local floor above and the immediately adjacent columns to reach eminent total collapse. One column failure basically causes adjacent columns to experience a 50% load increase, so they are within a hair of ultimate factored load right there, not considering the rapidity of such a load increase, which must be near impact conditions. If just one adjacent column failed in a full design load scenario, game over. Loss of lateral bracing to prevent column buckling even more serious.

It is also unlikely that a residential building ever gets fully loaded. Nobody I know puts 6" of concrete on their floors, nor makes a guest list based on 4 people per square meter and fills the room, nor would you expect that to happen for 50% of the units all at the same time.

That points the finger away from building dead and live loads causing failue.
Construction loads, poor workmanship, material defects become more suspect, but even generating high loads from remodeling work is not all that easy. Even considering maintenance anchors. Another red herring.

Quote (CE3527 (Civil/Environmental))

So the roof anchor permit is dated June 23, 2021 and the condo collapsed at approximately 1:20am +/- on June 24, 2021, less than 24 hours after the permit was issued. My experience with permits is generally the contractor doesn't schedule the work until they have the permit in hand, because sometimes there are unknowns on when you'll actually get it once you apply. Is there evidence that the contractor mobilized to the project and installed these anchors before the collapse?

Evidence beyond the presence of new roof anchors on the roof? I dimly recall some discussion of the after-the-fact permitting on an earlier page of this thread, but I may have seen it elsewhere instead.

Quote:

it's pretty illogical to discount a few hundred extra tons of load on an entire, but highly concentrated area.

Lets not over-exaggerate how much extra weight the change in flooring would actually add to a unit.

How'd those anchors on the roof get installed before the permit posted by JAKLED was issued? I'd tend to believe the permit was for some other anchors yet to be installed and has no relevance.

I'd also tend to agree that the ones on the roof are for tie off when working on the roof and not for use as tie off when working on the sides of the building.

The point of my posts is to generate out of box thinking, as I feel that is what it takes to solve this riddle. IMO it is a system of many parameters that led to the structure giving way to gravity.

As a child I built many things with erector sets, and this may not be a Spartan5 level analogy, but I think the tight original design wing-nuts will see this more from a by the book perspective, where as the loose wing-nuts will look outside the box at the warning signs that may have been overlooked because our Special Inspector Training is NOT GOOD ENOUGH yet to solve this unfolding new riddle.

This was a system of failures from original design to lack of well baby care that led to this collapse. Why did they not start working on ground level first, it was because Association would not allow pool out of service nor possibly loss of parking spots, so they started on roof of a time bomb.

I know when my wing-nuts were loose at the joints of my erector set vs tight joints, the load capacity and stability of the structure varied greatly. Now this was a young child figuring this out.

Loose joints probably were one of the biggest issues in this building, leading to racking of structure, thus shifting load paths over time and shifting stresses. Think about removing masonry in fill non load bearing partitions that may have been proving some racking support.

It appears column cold joints between floors were not well tied together. Slab deflections will put lateral stresses on the column to slab joints and could put the columns in towards the middle of some units, while pulling them away from slab to column joints in adjacent units.

Why can't some folks see this concept???

I would argue it takes a far different skill set to design a structure from scratch, with the Architect dictating a lot of problems for the structural engineer to figure out solutions too, that go against anything the EOR wants to do, but hey what happens if Architect and customer unhappy with EOR..... They find another EOR that will do what they want.....

Folks are ignoring the loose joints of this building, and the effects of vibrations of varying degrees on those loose joints, yet the joints are the most critical part of the design process.

Look at Hard Rock Collapse in NOLA. Did not the steel erectors leave out bolts at connections and leave the joints loose as they added floors above, coupled with design issues.

Loose joints whether steel or concrete can become a big issue.

So if you read this to this point, you realize I am a loose wing-nut.... I did the opposite of Demented and went from Structural start to Aerospace. Think about it, Aerospace engineers design stuff to blow up or exploit what Structural Engineers Design......

And AeroSpace Engineers do all this without a PE Stamp and the liability that comes from doing Public Structures....

The shaking of Champlain Towers appears to have started being noticed when the stimulus of pile driving started next door. Does that mean the pile driving caused the collapse. NO. But it may have been a key contributing factor to a exponentially decaying defective structure. And this construction happened after the 2018 Morabito Report.

What I really don't understand is why so many tight ass wind-nuts are taking such a hard stance that only a simple solution and only their theory could be possible.

You can not pick and choose which pieces of evidence you consider. It is all important, and must be considered and factored into the algorithm....... And that algorithm may not be a simple linear equation......

PS I typed this on the fly, and did not proof read, so there may be typos....

Think about it. I, K, L, M 9.1 Column line had cantilevered slabs to transport moisture into the exterior column line to slab joints at each floor column joint. Was the cantilever slabs well maintained to prevent moisture intrusion in this area? I think no, these were neglected just like the garage slab at wall interface. We can see the water soaking into the building in the garage tour. Water intrusion is not stopping at the exterior wall...

Edit for Spartan5. Dirac Live does a great job eliminating those room modes you are referring.

Quote (Loose joints probably were one of the biggest issues in this building, leading to racking of structure, thus shifting load paths over time and shifting stresses. Think about removing masonry in fill non load bearing partitions that may have been proving some racking support.)

In the country you can see numerous old collapsed timber framed barns... the reason... lack of maintenance. In the case of this condo... it was occupied at the time.

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

-Dik

I discovered with my Erector Set that if I installed diagonal bracing, I could leave the bolted connections loose, and it wouldn't fall down.

I also discovered no wing nuts. Mine came with square nuts and some crappy flat wrenches. Old school, I guess.



spsalso

@lionelhutz
To each floor, I agree minimal. To the columns and and piles with an unstable subsurface. Weight matters.

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

I was about to ask why the hallway sheer walls didn't halt the collapse, and then I realized that, viewing the security cam footage, they did, momentarily. First between the pool side and the street side of the center section and again between the center and the ocean (east) side. I think if this open design continues to be used, a way to limit the collapse needs to be designed. What are the thoughts on how the collapse propagated across the sheer wall central core of the building, and how it could be limited at that core?

SF Charlie
Eng-Tips.com Forum Policies

One thing that continues to haunt me on this building is that lack of evidence...at least from the photos...of SIGNIFICANT and dangerous degradation of the reinforcing within the columns. Sure, there is some spalling paint and a few locations of damaged columns and spalled concrete. But, it just seems to me that the apparent, observable, signs of continuing widespread rusting of reinforcing does not appear to be evident. I have done some repair designs on seriously damaged (by de-icing agents) columns and slabs. The amount of rust staining I encountered was way beyond anything that I have seen in the photos so far.

Was this building so tightly designed, or missing enough of the reinforcing at strategic locations, that poor maintenance was the secondary cause and not the primary?

I continue to wonder if the beam spanning between cols m9.1 and m11.1 was NOT bearing on the columns and, instead, was constructed hanging from the columns? If this is the case, and the stability relied on the horizontal bars supporting the loads in shear it would take very little reinforcing damage to release this beam from the support. This beam could then collapse at M11.1 and push against col M9.1. This could cause the collapse of the pool deck prior to collapse of the main structure as the structure tries to re-distribute the loads from the lost or displaced column. Many of us have theorized that this is the area of initial collapse.

I also continue to wonder why the collapse occurred so shortly after construction commenced? IF this area was subject to additional loading as a result of the construction activity could this beam support been jeopardized? Could slab rotation have tweaked the (maybe) poorly supported beam and been the trigger?

I also have my doubts that the overall lateral stability of the structure was up to the job. Rigidity attracts load. We have a, relatively, flexible east wing of the building (lateral load transferred by slab to column connections) bringing loads onto the first level framing system where those loads are distributed to the perimeter walls and lower columns. When I design a building, I design the systems to experience deflections at similar rates...ie the stiffness is compatible for the anticipated loads. IF locations of rigidity exist with poor connections, those connections may well fail and the loads will seek another path.

IMO, the biggest issue here is how we take the lessons from the collapse of this building and apply it to our designs going forward. IF this structure would have been constructed with additional shear walls would that have bought occupants some additional time to evacuate? I know many of us do design with consideration to preventing progressive collapse...these days. But, do we need to consider retrofitting existing buildings to limit the collapse potential? Maybe once we cross a threshold on occupancy?

Quote (Thermopile)

The point of my posts is to generate out of box thinking, as I feel that is what it takes to solve this riddle.

As long as we learn the lessons that this collapse shows us and implement improved processes going forward, to me that is more important than necessarily pinpointing the exact cause of the collapse. The more avenues of potential causation that we examine, the more we can reflect on the way things were done and hopefully improve them going forward. I'm a structural engineer, so I hope to eventually learn the cause of this collapse for the sake of closure. But in the meantime, there have already been plenty of design, construction/inspection and maintenance/renovation/durability issues identified to ruminate on. The least I can do for the victims and their families is to learn all I can from this to make my future designs more durable and resilient. For me it's more about the process than the final result. I think everyone on this forum has done a great job investigating the limited public info and employing the scientific method to imagine plausible hypotheses and vet them out.

Has anyone observed rusted through rebar from the plaza slab demolition? For all the talk about deterioration, I haven't seen much spalling and rusting from the top layer of rebar.

As for the deterioration caused trigger theory, my thinking is that the slow failure of the stepped slab added moment to the building column(s) which caused the creaking noises of the structure that were observed. I don't have a big enough margin to do that calculation, but a frame analysis could certainly serve to discredit my theory (there would have to be a bit of rotation in those columns to cause audible distress in the floors above). I take it as a given that people heard the noises that allowed them to flee the building before the collapse of the plaza slab followed by the building collapse.

As for lessons learned, that is premature. Until we can isolate the reason for failure, we can't address it.

Quote (Great post! Report Colostruct (Structural) 20 Jul 21 16:29 One thing that continues to haunt me on this building is that lack of evidence...at least from the photos...of SIGNIFICANT and dangerous degradation of the reinforcing within the columns. Sure, there is some spalling paint and a few locations of damaged columns and spalled concrete. But, it just seems to me that the apparent, observable, signs of continuing widespread rusting of reinforcing does not appear to be evident. I have done some repair designs on seriously damaged (by de-icing agents) columns and slabs. The amount of rust staining I encountered was way beyond anything that I have seen in the photos so far. )

You make several good points. We engineers who do this type of work regularly see deteiorated reinforced concrete members that look a lot worse than what we can see in the 2018 report and in the video of the parking garage taken by a prospective buyer a year or two ago. The beam you are referring to as the possible initiator of the collapse can be very clearly seen in the parking garage video. Although the beam appears to show some curvature (most likely due to deflections during casting), it does not show the type of structural distress that we would typically see as indicative of imminent failure. This is why I lean towards the theory that a section of parapet fell off the roof and impacted the column and/or beam.

Wouldn't it have been interesting to measure the lateral movement in the E-W direction over time, and during a hurricane event versus steady state???

This video is from a professor of civil and environmental engineering at Northeastern, and an expert in "progressive collapse" of concrete structures. He addresses a possible scenario for the Surfside collapse.

Link

Quote:

You make several good points. We engineers who do this type of work regularly see deteiorated reinforced concrete members that look a lot worse than what we can see in the 2018 report and in the video of the parking garage taken by a prospective buyer a year or two ago. The beam you are referring to as the possible initiator of the collapse can be very clearly seen in the parking garage video. Although the beam appears to show some curvature (most likely due to deflections during casting), it does not show the type of structural distress that we would typically see as indicative of imminent failure. This is why I lean towards the theory that a section of parapet fell off the roof and impacted the column and/or beam.

My theory is that this beam was NOT failing prior to the collapse. It was just set up for failure. I have a project where the contractor didn't provide enough bolts at a beam to wall because the architect did not want to see the side tabs. This connection would have, likely, held up fine. UNTIL that portion of the structure became stressed to load for some reason or one of the bolts deteriorated, or a car hit the roof of the garage...

The trigger for failure could have been a falling parapet section. I wouldn't rule that out. I just feel it is more likely something as simple as damage that occurred due to a vehicle on the plaza or storage. I also cannot rule out the possibility that the plaza was saturated by the recent rains and the reason it was impacted more now than in prior weather events had something to do with the activities on the roof.

I haven't done a deep dive on the roof anchors, because I don't believe they're the cause, but to just answer some questions, it seems at least some of the roof anchors were installed and possibly split into two phases, because the drawings posted on the town website only show anchors on the east side/penthouse roof (basically the part that collapsed), but photos show other anchors on the part that didn't collapse, that are not on the drawings. Possibly an earlier phase of the project? I noted that the posted plans are called Phase IIB. Sorry if this retreads on past posts, like I said I've not paid much attention to roof anchors.

Quote (Teguci (Structural)20 Jul 21 16:40)

that is premature. Until we can isolate the reason for failure, we can't address it.

Yes, we need access to more information, (i.e. drone videos, etc.) information that the response team is holding very close to their chests.
I hope we can, however, discuss how to mitigate the propagation of the failure.

SF Charlie
Eng-Tips.com Forum Policies

For some reason, not all roof anchors are NOT on same drawing. It takes looking at two sheets to see them all. I can’t remember sheet numbers

Has it been determined what the blue spray painted items represent vs the red spray painted areas?

edit: nvm

Hi everyone, I'm a double E graduate, new to this forum. This collapse caught my interested.

I just wanted to point out one thing from the TicTok video that I haven't seen anyone discuss.

After reading this thread for a few days, I'm seeing a lot of evidence that m9.1 was the first column under the building to fail. It must have failed within a few minutes of the tiktok video since the building collapsed soon after. I took a closer look at that video for signs of failure, I noticed that the top of the column M9.1 was missing in the image. I almost fell out of my chair when I first saw it.

It's very possible it's just a video compression or motion compensation artifact. I don't see how it's possible for a column to actually fail in a even slice.

I am pretty certain there is just something in foreground obscuring the top of the column.

In order to obtain a 3D image, all that is necessary is to have two distinct views spaced approx 6 inches apart. There are two such views on the TIC-TOC video. So for what it is worth, here is a 3D view looking into the garage. In order to see the 3D view it is necessary to view this picture cross-eyed, such that the left image is viewed with the right eye, and the right image is viewed with the left eye. Best viewed from at least 18 inches away from the monitor.

There is nothing in this view that jumps out, but at least looking at it in 3D it is possible to discern closer items vs farther items. For example, the third column looks like its top half is obscured by the collapsed pool deck. For what it is worth, another view.

Yeah that's definitely something in the foreground, you can see it clipping the other column to the left as well. I think in the 2020 video tour there is a black PVC pipe running across somewhere there?

EDIT for confusing column numbering - the still visible columns appear to be 'M8', 'M9.1' and 'M11.1'. The 9.1 line is basically the same as the 10 line but not quite, and ditto 11.1 vs 12. There is no 'M10'.

@Demented.
A extra couple of hundred tons. Over 400,000lbs of flooring and kitchen cabinets and such were added to the units in the section where the collapse initiated?

Heck... I've designed foundations for transformers that weighed that much, and there were 6 of them. They are at grade level and cannot fall much further.

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

-Dik

Reposting a picture that Demented posted earlier for a different reason. Look at column '38'. This would be column M/N15 (midway between column lines M & N on column line 15. It is just north of the spa and supported relatively short spans to the south and east because of the spa and pool. It looks like the structural slab punch sheared completely around the column, but the overlay, mortar, and tile to the east did not collapse. I believe that the piece of slab leaning on its south flank is just structural slab that separated and fell while the slab on the west side is everything up to and including the pavers. Notice the missing layer compared to the slab to the left (north) side of the column. Just eyeballing it, I'm seeing maybe a 5-6" structural slab, 4" overlay, and 3" mortar. That's a big difference compared to the 9 1/2", 2 3/8", and 1 3/8" thicknesses they found at the planters.

Also, I don't know if anyone has questioned the overlay. Was this part of the original construction or a later repair? If it was original, why? Is it possible that they sloped the slab to the south by just thinning it down. Perhaps the pouring crew assumed that it needed to be sloped, but the forms were level. After the mistake was discovered, they chose to overlay it to bring it up the the 9 1/2" spec. They started with a 2" overlay at the south side of the east wing, and it ended up being 4-5" think at the south retaining wall. They justified the thin structural slab as okay because it only has to support a few sunbathers and lounge chairs. I also don't see any top bar in that section.

I'm starting to think that the failure could have started at the south side of the pool slab where the slab was thin, propagated by punch shear to the stepped area, then moment loads from the unsupported patio slabs that are hooked into column line 9.1 resulted in weakening and eventually failing those columns.

That 3D composite is a genius idea. I don't see anything much in it though. (I think you posted it wrong way around though?)

How come there are these 2 videos? Is one from Adriana and one from her partner? Did a single phone record the whole video in stereo?

The dark horizontal object along the 'bottom' of the debris looks significantly in front of anything else. It could be a piece of waterproof membrane or something edge on to us. It looks too thin to be a piece of slab though.

It looks in 2D like the white object in the middle overlaps it, but I think that's actually 2 different objects, one behind and one overlaid. The grating of the gate is really obstructive though. One can imagine a piece of sagging slab behind the water, sloping towards us, but I'm not sure if that is actually there.

The left side of the debris looks a lot closer than the right, consistent with a diagonal failure line starting over by the M line and implying that (at this early stage) L and K are probably not collapsed out of shot.

That's definitely a planter (well, a concrete box at least) where M11.1 should be. Couple of interesting things about that though
- It seems to be sitting directly on the garage floor, or at least only on a thin piece of debris. How is that possible? Surely it should be on at least the 9" of slab + toppings? Where is the M9.1-M11.1 beam which should also have been under it?
- One image (the one you put on the left) shows more debris in front of this planter than the other. It might just be a camera artifact, but the two images are very consistent otherwise. Does that debris appear during the video?

EDIT the thing which I've never understood about this video, and which this composite doesn't help with at all (because nothing obvious is blocking it), is why can't we see M12.1? We know that column still stood, and unless the pool deck has fallen and is completely blocking the shot, either the bottom of that column (beneath the deck) or the top (poking through in puncture shear) should be visible.

Something that continues to bother me about these roof anchors (as a total layman):

Some anchors are installed atop columns. But others are installed on the overhang.

This one in particular was closest to the edge of the still-standing portion and can be seen to be clearly on the overhang from other angles (Can't find a good picture at the moment)


Why not have anchors only over columns to ensure that the roof overhangs are not compromised in any way? Even as a layman it occurs to me that it is a bad idea to cut/drill/add weight onto a cantilevered structure. Of course if it is on the plans I would assume that the engineer had considered this...

Shots of the two sheets from the plans



Again very much a layman perspective, but as many others continue to point out the collapse happened after/during roofing work and anchor installation so it is not prudent to simply ignore problems coming from above.

MikeJ65 - good observations. The best I can tell from the original drawings is the structural slab was supposed to be flat based on only one uniform elevation given for it. The plumbing drawings showed sloping towards deck drains, I assumed this was accomplished with the sloping overlay over the flat structural slab. The architectural finish drawings called for the pool deck called to have simulated keystone, which I think was a the pattern stamped into the overlay. Lots of speculations of course - based on fairly undetailed 1979 drawings.

There are actually 3 layers on the structural slab from the Morabito core sample. Structural deck (they found 9.5" where they drilled), plus the overlay topping (original?), plus tile/mortar (renovation?) + waterproofing/sand/pavers (renovation #2?).

As for the slab failure in the photo, I agree with your observation. It seems like the slab continued to fail along a straight line of which others speculated is a construction joint separating the area around the pool with the rest of the deck slab, and whereas the topping above did not fail along that line. It also looks to me like the column has been pushed out of plumb possibly by the falling deck, but it's hard to tell with that angle. If it did get pushed by the deck, it might support that this happened elsewhere like near the building collapse.

I found this Briefing Map on Twitter, the legend is too blurry to make out, but notice the Black circled columns south by the pool and the sheer wall, also black crossed thru square.. Then there are blue dots spread out but they're not marked columns.
Can someone explain what the black circles and blue dots represent?

Link

Quote (rodface)

This one in particular was closest to the edge of the still-standing portion and can be seen to be clearly on the overhang from other angles (Can't find a good picture at the moment)

Roof anchors. Again. Notice it’s not any closer to the edge than the humongous communications array (I presume) with its massive wind loading (which is obvious).



That installation (it’s the thing to the lower-right that’s as big as the circle around the anchor you drew) didn’t bring the building down. But somehow a little bit of hammer drilling into a thousands of tons structure somehow vibrates the pool slab free 12 stories below or otherwise snapped a parapet off? That dog just don’t hunt.

People are so fixated on things they can’t see the forest for the trees. Now we are squinting at two different pictures to make them 3D? Woof!

The roof anchors are a non-issue here. They're used for fall-protection tie-offs. If some hammer drilling and Hilti's are compromising the structural integrity of a roof, you have way way bigger problems going on here. They're a moot point... so why even bother discussing it?

If the parapet above the collapsed pool deck did fall, it's mostly made of CMU (or cinder blocks). Once that hits the ground, it's going to shatter like glass. *IF* that did happen, for that to bring down a structural slab points to structural issues (weakened concrete / compromised rebar) on the pool deck as pointed out in the 2018 report. The cantilevered roof overhangs and balconies are part of the roof / floors and tied in to the structure with rebar. If those were to fail, they wouldn't just drop away from the building cleanly unless you cut all the rebar at once and sawed them off. It's a proven construction method as indicated by any Frank Lloyd Wright or brutalist architecture style building. I don't see that being a primary cause either.

I do find it remarkable that a failed slab or column took down such a large portion of the building. We've all seen the CDI building demo videos where they're putting explosives in just about every column in the first 2-3 floors of a building along with other methods to weaken the structure prior to detonation to bring it down on itself. This building fell right in it's own footprint without any such assistance. Was the concrete too weak? Did they not use enough rebar or the right thickness of rebar? Was the rebar completely rusted away?

Compare this to the 1995 bombing of the Murrah Federal Building in Oklahoma City. Some similarities here... reinforced concrete slab and column construction. The bombing took out 4 columns but most of the building remained standing.

https://buildingfailures.wordpress.com/1995/04/19/...

Like with any major accident / disaster - there is no singular cause. A series of events over the years led up to this collapse.

I find it odd that beams 33,34 and 35 appear to be exactly in place. They also appear completely intact. Does this mean the columns below (N8,O8, N9.1 and O9.1) did not fail?

Can anyone please advise me as to where can I see the reinforcing for the beams selected? I see this as a critical area. Also a dimensioned drawing -Plan?
Thanks,

Vance Wiley, that's a typical "Beam A"

Quote (sgw1009 (Computer))

In order... to obtain a 3D image

That's the best sense of what is or isn't in there I have seen. I think it adds slightly more than just depth perception. But now I am permanently cross-eyed. I have the sense that the piece laying cross-wise that is dark may actually be the missing column as though a partial length of it is still white but another part has had the exterior crumble or shatter to expose the core thus it is darker.

Edit: after refining my cross-eyed stare, the dark portion is a little too dark to be concrete..... unless somehow it got tar all over it. I mean it's not like thing beside it is a tar buggy or anything like that.

Edit2: The other things that the double vision overlay does is provide noise reduction and dithering. It dithers the width of the gate bars so they seem thinner and block less (you see around them a bit). Noise reduction occurs by emphasizing what is there and de-emphasizing what it not. The added benefit is you get depth perception.

Vance,

That model is not accurate where you have the patio slabs. The beam along column line 9.1 is just the slab step and wouldn't look like that at the patio to living floor step since it is only a 7" step.

Quote (Optical98 (Computer)20 Jul 21 22:58)

Can someone explain what the black circles and blue dots represent?

The "blue dots" are symbols from the legend. They are probably entries in the source document for this map. The black circles, some with slashes through them or text are whatever the briefer said they were. What's more interesting is probably the shadows of the columns...

SF Charlie
Eng-Tips.com Forum Policies

Quote (spinspecdrt)

I find it odd that beams 33,34 and 35 appear to be exactly in place. They also appear completely intact.

lol. Like with many, many photo analyses on these threads, I have to wonder: how can you possibly see that?

This image is 640x412, and rife with jpeg artifacts. I can only tell that some sort of something was at each column location. The state of the column and how intact it is? No way. Maybe you're looking at a high-res view or something?

From the photos of the garage provided by a prospective buyer, Beam A at column Line M is dropped below the slab and not integral to the slab as detailed above. I believe these beams may not have been constructed as part of the slab and may not have been supported in directed bearing on the columns. I believe they may have been hanging off the horizontal reinforcing. That also explains the intact “frame” mentioned above by Spinspecdrt. 3DSoftwareDev, I think the resolution is clear enough to see that something different is going on with these beams. I see these intact beams as some evidence that the plans and the construction of the transfer beams is not consistent or there would be slab attached to these beams.

Quote (rodface)

Something that continues to bother me about these roof anchors (as a total layman):

Some anchors are installed atop columns. But others are installed on the overhang.

Why not have anchors only over columns to ensure that the roof overhangs are not compromised in any way? Even as a layman it occurs to me that it is a bad idea to cut/drill/add weight onto a cantilevered structure. Of course if it is on the plans I would assume that the engineer had considered this...

Probably wouldn’t be a bad idea to understand how suspended scaffolding is arranged before questioning the anchor positions.

As a layout example:



And load test example:

Quote (spinspecdrt)

beams 33,34 and 35 appear to be exactly in place. They also appear completely intact. Does this mean the columns below (N8,O8, N9.1 and O9.1) did not fail?

from one of the videos posted a few days ago (https://youtu.be/jI6Up5Nv70c):

Quote (Colostruct (Structural)21 Jul 21 02:22)

From the photos of the garage provided by a prospective buyer,

Interesting. Where should I look to find these photos? Thanks

SF Charlie
Eng-Tips.com Forum Policies

Quote (Thermopile)

The point of my posts is to generate out of box thinking, as I feel that is what it takes to solve this riddle. IMO it is a system of many parameters that led to the structure giving way to gravity.

As a child I built many things with erector sets, and this may not be a Spartan5 level analogy, but I think the tight original design wing-nuts will see this more from a by the book perspective, where as the loose wing-nuts will look outside the box at the warning signs that may have been overlooked because our Special Inspector Training is NOT GOOD ENOUGH yet to solve this unfolding new riddle.

This was a system of failures from original design to lack of well baby care that led to this collapse. Why did they not start working on ground level first, it was because Association would not allow pool out of service nor possibly loss of parking spots, so they started on roof of a time bomb.

I know when my wing-nuts were loose at the joints of my erector set vs tight joints, the load capacity and stability of the structure varied greatly. Now this was a young child figuring this out.

Loose joints probably were one of the biggest issues in this building, leading to racking of structure, thus shifting load paths over time and shifting stresses. Think about removing masonry in fill non load bearing partitions that may have been proving some racking support.

It appears column cold joints between floors were not well tied together. Slab deflections will put lateral stresses on the column to slab joints and could put the columns in towards the middle of some units, while pulling them away from slab to column joints in adjacent units.

Why can't some folks see this concept???

I would argue it takes a far different skill set to design a structure from scratch, with the Architect dictating a lot of problems for the structural engineer to figure out solutions too, that go against anything the EOR wants to do, but hey what happens if Architect and customer unhappy with EOR..... They find another EOR that will do what they want.....

Folks are ignoring the loose joints of this building, and the effects of vibrations of varying degrees on those loose joints, yet the joints are the most critical part of the design process.

Look at Hard Rock Collapse in NOLA. Did not the steel erectors leave out bolts at connections and leave the joints loose as they added floors above, coupled with design issues.

Loose joints whether steel or concrete can become a big issue.

So if you read this to this point, you realize I am a loose wing-nut.... I did the opposite of Demented and went from Structural start to Aerospace. Think about it, Aerospace engineers design stuff to blow up or exploit what Structural Engineers Design......

And AeroSpace Engineers do all this without a PE Stamp and the liability that comes from doing Public Structures....

The shaking of Champlain Towers appears to have started being noticed when the stimulus of pile driving started next door. Does that mean the pile driving caused the collapse. NO. But it may have been a key contributing factor to a exponentially decaying defective structure. And this construction happened after the 2018 Morabito Report.

What I really don't understand is why so many tight ass wind-nuts are taking such a hard stance that only a simple solution and only their theory could be possible.

You can not pick and choose which pieces of evidence you consider. It is all important, and must be considered and factored into the algorithm....... And that algorithm may not be a simple linear equation......

PS I typed this on the fly, and did not proof read, so there may be typos....

Think about it. I, K, L, M 9.1 Column line had cantilevered slabs to transport moisture into the exterior column line to slab joints at each floor column joint. Was the cantilever slabs well maintained to prevent moisture intrusion in this area? I think no, these were neglected just like the garage slab at wall interface. We can see the water soaking into the building in the garage tour. Water intrusion is not stopping at the exterior wall...

Edit for Spartan5. Dirac Live does a great job eliminating those room modes you are referring.

This is take 2. Hopefully my rambling thoughts make sense, I had just lost an hours worth of typing after a long day.

I enjoy being a loose wing nut. It's helped me achieve some things that I am quite proud of. Although life took me away from finishing my degrees, I never stopped engineering. Thankfully the aerospace industry is what it is. I would rather put my name on any print or fabrication piece in the aerospace field than be responsible for anything done in the South Florida structural, specifically ocean front, field.

Why can't people see the concept? *shrugs* One day people will learn to use both eyes. I doubt my own ideas more than anything else which is why I'm trying so hard to find evidence of anything else. All the odd stuff that makes little sense. There's just so much wrong here. So much wrong.

Up until recently I was under the impression that the building stood on 42" and 48" precast 14"x14" columns. I was unaware of the drawing revisions that specify Franki piles. Still haven't seen it, but I am not saying it doesn't exist. The version of drawings I have, dated with 1-17-80 revisions and notes, calls for only the following columns to sit atop PIF (I may be wrong on some of these because of the .1 denotations)
B1.1, D1.1, D2.1, D5, D8.1, D11, And the entire 1.1 columns row.

The remaining columns were to sit upon 42" and 48" precast 14"X14" driven piles. Floating in the sand, where fucking boats used to flow through!

I know it seems stupid. No one would ever actually go ahead with possible building something like that. But then again, no one would ever omit a large portion of steel reinforcement...

I have seen some shit go on here. You guys ever catch a shop welding nelson studs to unprepped steel for embed plates, but blasting it with aluminum filler and hoping the hot dip galv and going in the concrete before the inspector gets there gets it to pass inspection? Not saying everything in Miami is suspect, but Miami we cannot blindly assume the building is built as intended.


Treat the piles as suspect. The additional weight of those pavers, the tile, the windows, the cars, the rain, etc, all really starts to look like scary numbers added on top of the existing building. Subsiding in key locations that are slightly quickened due to heavy loading, could cause portions of the building to sink slightly more, and at an unusual way, compared to the more secure areas. Cause of the collapse? Probably not. But a very valid point, and one that could also affect other buildings.

Another thing we need to remember, is there was a beach restoration project done in surfside. The beach that we see there now was trucked in because it damn near all eroded away. Water may have found a way past the bulkhead. The pile driving from next door definitely didn't help the settlement of loose beach sand either. Even if they were all Franki piles, this building was not set on any solid rock surface. Where is the logic here?



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

3DSoftwareDev, I can clearly see the beams. No squinting, enhancement or imagination required. It's the only location in the building this arrangement of beams occurs. Obviously from the picture you can't tell the condition of the columns.

Quote (Optical98 (Computer)21 Jul 21 02:39)

Wow! These must be hot off the presses. Where'd ya' get 'em?
Looks like they have the whole garage cleared.

SF Charlie
Eng-Tips.com Forum Policies

SF Charlie

Senator Jason Pizzo's Twitter

Link

Quote (spinspecdrt)

3DSoftwareDev, I can clearly see the beams. No squinting, enhancement or imagination required. It's the only location in the building this arrangement of beams occurs.

My apologies, I read "beams" and thought "columns" because at some point previously in these threads, someone conflated the two and now I'm screwed up.

Yes, that beam assembly is certainly more clear than whatever remains of the columns. It was discussed previously; there are some decent close-up shots of it in previous pages I think. Seems to be intentionally kept intact by the on-site crew.

An interesting note is, of the 80 units that collapsed, 34 of them were empty (36 if you count 611 and 111 that escaped). I've not researched the later demoed units.

Quote (From the photos of the garage provided by a prospective buyer,)

I can imagine the conversation.

Buyer to engineering consultant: "So, do you think we can salvage the foundation to save money?"

Quote (spinspecdrt (Materials)20 Jul 21 23:52
Vance Wiley, that's a typical "Beam A")

Thank you. Not such a great beam -

Quote (MikeJ65 (Mechanical))

And thank you, Mike.

Quote (Optical98 (Computer)21 Jul 21 02:52)

Senator Jason Pizzo's Twitter

Thanks!

SF Charlie
Eng-Tips.com Forum Policies

SFCharlie

This is the photo of that beam on Column Line M that is causing me so much concern.

• https://files.engineering.com/getfile.aspx?folder=cb11aafe-6b71-45f0-9b82-3

Quote (spinspecdrt)

I think they meant the prospective buyer touring unit 611 in the youtube video, but I did have the same thought... because I was wondering how much demolition will be needed? Will they eventually yank out all of the piles and we will know the truth about what in fact was installed back in ‘79?

Quote (Colostruct (Structural)21 Jul 21 04:32)

beam on Column Line M that is causing me so much concern

Here are two higher quality outtakes from that video

SF Charlie
Eng-Tips.com Forum Policies

• https://files.engineering.com/getfile.aspx?folder=2ec4bbed-796b-4f0c-929f-e

Screen shot #2

SF Charlie
Eng-Tips.com Forum Policies

• https://files.engineering.com/getfile.aspx?folder=79483564-a169-4458-8dd7-9

So maybe a law which if a building collapses with people still living inside it, they have to turn the entire foundation into a memorial. Meaning no rebuilding possible. This will give a financial incentive to redevelope.

Quote (AutisticBez)

So maybe a law which if a building collapses with people still living inside it, they have to turn the entire foundation into a memorial.

That greatly reduces the compensation available for families who lost someone, and survivors who lost all of their possessions and home. I don't know if these numbers are accurate, but I read something like a maximum insurance payment of $50M and the site being worth around $100M. If those numbers are correct, selling the site triples the available compensation. Money can't replace the lives lost, but it can help those who lost someone or their home.

It's tricky, but the sale isn't just money going to rich property tycoons or some greedy corporate entity.

I would assume the clean up costs are going to eat up any insurance payout.

A harsher inspection and building condemnation regime would possibly incentivise (terrify) owners into re-investing more in care and maintenance but you could also see perverse outcomes: "why reinvest when some bureaucrat might condemn it anyway?". This building needed 30 mill spent on it (I'm doubling the 2018 estimate for stuff they couldn't see). Would the equivalent of that dribbled over the 40 years have saved it?

This

The building integrity guy nails the collapse mechanism. Perhaps the theory could be tuned up a bit, but his idea that delamination of the slab rebar mats provided the avenue for failure is a good fit.

There was a release of permits for their repairs https://surfside.one/public-records-search/

@Demented, So after viewing Building Integrity's latest video, perhaps with input from undisclosed sources, what do you think of you rain accumulation theory now??? Versus some of the other theories

Edit: I think I like my chances better on a 737 Max than a high rise condo sitting on reclaimed ocean???

A big issue is that people don't intuitively understand exponential growth.

The 2018 report warned that structural damage from corrosion was increasing exponentially. That should be a very alarming statement, even if the damage seemed minor at the time. But people don't understand how quickly an exponentially growing problem can change, and think that since things are mostly fine now they've got plenty of time. For evidence that most people don't understand exponential growth, see the reactions to how fast the COVID-19 pandemic grew.

We should do better at communicating just how scary exponential growth of possible failure modes is. Even engineers here have said the 2018 report wasn't that alarming, despite warning of exponentially growing corrosion in structural members! Exponential growth means very slow change, up until a turning point when suddenly the change gets ridiculously fast. A structure with exponentially decreasing strength (like this) would be expected to appear fine for years, right up until it suddenly lost all strength and collapsed. This collapse is exactly what I'd expect for an exponentially growing failure mode.

@thermopile
Going to give it a listen now.

If it's about the layering, someone some day gave the OK on the job site to pour the pool deck in two layers, with the final top layer encapsulating the upper rebar. Instructions were given to rough the surface, and that was done simply by just letting it begin to cure as it laid.
Or so I have been told.

Made laying the top rebar much easier. Why spend the trouble tying the rebar up properly?

Very common practice here.

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

Although the word "exponential" was used in the report, you are right that it's a word very much misused, and I am sure the term was not used in a mathematical sense. It was just used in a lay sense to indicate that the problems would get progressively worse the longer it was left.

Exponential means a doubling in a fixed time period, the period could be a second, a year, or a decade. Since the report does not specify a time period, nothing can be inferred from that statement about any timing involved.

Now if the engineer had said "the building will catastrophically collapse within 5 years" then that might be different, but there was no way he could know that, and I don't think he would even predict.

We need to be beware of Outcome bias. The interesting thing is that symptoms shown at CTS were not particularly severe, nor showing imminent collapse - *assuming* that the building was built to spec.

It makes me wonder, how often does it happen that a building inspection determines that a collapse is imminent (i.e. within a month), and the building subsequently collapses of it's own accord?

Still many factors in play, just the layer theory sure provides some good rationale to sudden collapse after a number of years.... and just needing a nudge at the right moment to set progressive things in motion. It would appear the interior slabs at exterior balcony slabs in area of IKLM 9.1 could have been weaken from moisture intrusion or now perhaps layering of those slabs too??

Layering could explain the shaking of building too.....

So I would argue the signs were there, but perhaps training and codes have not caught up with this risk? Actual construction methods is on the Contractors. But sure would be interesting to know who gave approval to layering of structural slab and how often that occurs?

@Thermipile

I really need to give a watch not a listen it seems.


However my take on water accumulation leading to it? In my honest opinion, it only enforces it, but in no considerable way. It only raises more questions and possibilities that need to be investigated. From the beginning I stated how I feared water may have been pooling and collecting in between the layers, and upon failure, thats what we saw leaking in the tiktok video.


I might not have mentioned it as I felt it were not likely or possible, but water hydraulicing between the slabs could have led to shifting.

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

I haven't seen any photos, yet, that show that widespread deterioration of the reinforcing in the deck was occurring. As I have mentioned before, reinforcing "bleeds" like crazy when it is injured. Was someone cleaning up the stains on columns? Was RUSTY water reported to be dripping on cars? Where are the stains on the basement slab?

I continue to wonder if there were serious deficiencies in this construction. We have what appears to be some variations in what we see on our limited photos and what the plans indicated including...a beam at the initial failure zone that is not cast into the slab, beam frames that dropped intact without ties to the slab, missing top reinforcing over columns, apparent horizontal construction joints in structural slab, poor concrete cover, waterproofing failure. That's just what I see from limited photos.

My theory is that the recertification engineer and the remediation construction company walked into a ticking time bomb and had no idea of the extent of the structural deficiencies. Anyone show up late to a game of Jenga? How could one predict that a localized slab deterioration would telegraph into the adjacent building and bring it down?

It seems that there has been a tremendous amount of technological improvement to the process of applying concrete to the fabrication of a building's structural elements since the date of this buildings construction ( 1980). Recently minted engineers might not be aware that there was not available in 1980 super-plasticizers, low cost finite element analysis software, galvanized or epoxy coated rebar,fine pozzolans for reduced permiability, or laser based measurement devices. The NIST analysis of this building's demise ( and the review of all other 30+ yo buildings) will need to keep in mind the level of technology used at that time, and it would not be surprising to find that the actual concrete properties do not meet the design specs due to the likely use of a higher water to cement ratio .

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

Quote (davefitz)

The NIST analysis of this building's demise ( and the review of all other 30+ yo buildings) will need to keep in mind the level of technology used at that time

So do we condemn and demolish all of the circa-1980s buildings on the beach in Florida, Alabama, Mississippi, south Texas (and other places)?

This building had at least one design flaw (the "beam" at the change in slab elevation and the lack of isolation of the pool deck and the main building).

The design specs weren't met because of "higher water to cement ratio"?

And THAT'S supposed to be OK?

Of course, the PE and/or architect on the job would be consulted. And he presumably would have approved.



spsalso

Quote ("higher water to cement ratio")

...bad for corrosion resistance.

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

-Dik

Champlain South and the municipal garage in Coral Gables both appear to be/have been short on rebar.

Breiterman inspected and certified both buildings.

I would think that a good place to start inspecting is all the other building Breiterman inspected and certified. Not just buildings older than 40 years, but ALL of them.


spsalso

Quote (demented)

Very common practice here.

Where is "here" (in general terms)?

Quote (spsalso)

Of course, the PE and/or architect on the job would be consulted. And he presumably would have approved.

You'd think so, but you'd be unfortunately surprised at how often water gets added to the truck after the testing even takes place.

There was one time they didn't even wait for the concrete testing crew to leave, so the report I received had notes that although the strength characteristics of the tested concrete were within specifications, water was added to the truck AFTER the test cylinders were cast.

Needless to say, a few angry phone calls were had that day, because I didn't receive the report until 7 days after the pour. So not only did I rip the contractor a new one, but I also gave the testing company a piece of my mind for not calling me the second they saw that happen.

Quote (Great post! Report Colostruct (Structural) 21 Jul 21 14:44 I haven't seen any photos, yet, that show that widespread deterioration of the reinforcing in the deck was occurring. As I have mentioned before, reinforcing "bleeds" like crazy when it is injured. Was someone cleaning up the stains on columns? Was RUSTY water reported to be dripping on cars? Where are the stains on the basement slab? I continue to wonder if there were serious deficiencies in this construction. We have what appears to be some variations in what we see on our limited photos and what the plans indicated including...a beam at the initial failure zone that is not cast into the slab, beam frames that dropped intact without ties to the slab, missing top reinforcing over columns, apparent horizontal construction joints in structural slab, poor concrete cover, waterproofing failure. That's just what I see from limited photos. My theory is that the recertification engineer and the remediation construction company walked into a ticking time bomb and had no idea of the extent of the structural deficiencies. Anyone show up late to a game of Jenga? How could one predict that a localized slab deterioration would telegraph into the adjacent building and bring it down)

I couldn't agree more. Reinforcement that is corroding inside of a concrete slab or beam results in heavy staining, cracking, and spalling of the concrete due to expansion of the rusted rebar. This is incredibly common in Florida and especially with coastal bridges and buildings and is typically visible from a mile away. The video of the sub-level parking walkaraound just doesn't show any of that in the critical area. In fact the only place you see that is next to the pool which stayed up throughout the collapse.

Quote (Tmwaits1)

Reinforcement that is corroding inside of a concrete slab or beam results in heavy staining…

Raysa Rodriguez (907) took a video in the garage to accompany her 2018 class-action lawsuit. It shows water stains that appear to be rusty.

Link to article containing video

Quote:

So do we condemn and demolish all of the circa-1980s buildings on the beach in Florida, Alabama, Mississippi, south Texas (and other places)?

It may (partially) come to that. Insurance companies are going to have a lot to say about it. If nobody will put policies on a building, it realistically will become a demolition project. There is already talk that a lot of insurance companies down here are watching this VERY closely.

There is a reason for all the polycarbonate panels at the garage ceilings...........Perhaps rust diversion was one, after Association paid for car repaints, and of course you need to clean up rust stains for perspective buyers.

I assume Florida is a Buyer Beware State?

Lots more core sampling is coming to Florida.......

> @Colostruct - As I have mentioned before, reinforcing "bleeds" like crazy when it is injured. Was someone cleaning up the stains on columns? Was RUSTY water reported to be dripping on cars? Where are the stains on the basement slab?

Have we seen any photos of the top rebar of the pool slab? The water infiltration theories relate to rebar that's well hidden and wouldn't be visible from beneath.

Though I do agree that most of the rebar we have been able to see has looked relatively unrusted. There doesn't seem to be as much in the real building as in the specs in places, but that's a different question.

Is it possible that those columns were cast too tall for the lowered pool slab?

From the photos I have seen of the rebar in the patio deck, they actually look to be in good shape. I noticed the patio deck columns had what looks like some sort of coated rebar in them. Thus could it be the rusting was not that bad in the slab as a whole, but rather it was just the layered pour that was the big issue?

Edit would not take as much rusting to delaminate a layered top pour with rebar only 3/4" down

The top of the enlarged areas of pool gutter system, that looked so bad in photos, was actually a maintenance rework according to the surfside permit documents, and not original. They poured on top of cut off walls, it appeared.

Link: https://uc3f9146c21b4c345522c07de6ff.dl.dropboxuse...

https://www.miamiherald.com/news/local/community/m...

@Aapop,
Long by just enough for someone to have dropped a tape from the top of the form and forget a very important dimensions?



Unlikely, but not impossible.

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

In the 1995 to 2000 time span, apparently the major water issue was saltwater from below instead of fresh water from above. William Espinosa, who was maintenance manager during that period, said,

“I remember having some exposed rebar all the time,” Espinosa said. “They would come in, plaster it up with cement and then it would reappear in other spots. But nothing like a real big, big crack or anything like that. My biggest issue, which was it was just the water. The amount of water would come in there. It was all saltwater,” he said. “It was coming from the ocean.”

Skipping ahead 20 years, the 2020 garage video and the 2018 MC evaluation both show many examples of epoxy ports in the garage ceiling, which were then painted over or hidden behind plastic water diversion shields. Gabe Nir told the WaPo, “There was the water that pooled in the parking garage after rain, he said, and the uneven pool-deck pavement. Sometimes when he stepped on it, water would seep through the cracks.”

Could the epoxy injected into the most distressed parts of the slab have helped accelerate the delamination of the layer containing the top rebar?

Some recent research findings on a punching/delamination slab failure mode: https://www.structuremag.org/?p=11552. I wasn't previously aware of this mechanism.

@MaudSTL,

That testimony is pointing clearly to a floating concrete canoe, on a larger scale than the ones engineered by engineering students in my college dark ages.

The garage was being attacked both from above and below. The deck slab was under constant assault by rainwater and salt spray. The garage slab was under constant assault by saltwater intrusion and tidal pressures. The subsidence that occurred between 1993 and 1999 could not have helped. The garage video shows a long crack in the floor, and large area that appears to have been patched at some point.

Quote (jayrod12)

You'd think so, but you'd be unfortunately surprised at how often water gets added to the truck after the testing even takes place.

There was one time they didn't even wait for the concrete testing crew to leave, so the report I received had notes that although the strength characteristics of the tested concrete were within specifications, water was added to the truck AFTER the test cylinders were cast.

Needless to say, a few angry phone calls were had that day, because I didn't receive the report until 7 days after the pour. So not only did I rip the contractor a new one, but I also gave the testing company a piece of my mind for not calling me the second they saw that happen.

So it sounds like you would then certify that the pour was NOT to spec. That would be very interesting.

If adding water is all that common, then it hints that a certifying person should be on site at those times to see that that doesn't happen. Or to "certify" that it did. If it did.

Maybe I am misunderstanding what a PE is supposed to do here. My belief is that he/she designs and specifies much of the structure, inspects the structure during construction to affirm that the plans and specs are being followed, and then affirms same in writing with a stamp added.

Am I wrong somewhere in there? I don't get much involved with structure in my work, but it sure is interesting!


spsalso

I see from pictures posted by Spartan5 back on July 5 that a typical column top poking through the pool deck seems to have been tied to the slab by 4 pieces of rebar embedded in the column, bent 90 degrees, and extending into the slab about a foot.

I haven't a clue how to read what the drawings say SHOULD be there. Is the above what the drawings call for?


spsalso

Quote:

Spsalso: So it sounds like you would then certify that the pour was NOT to spec. That would be very interesting.

If adding water is all that common, then it hints that a certifying person should be on site at those times to see that that doesn't happen. Or to "certify" that it did. If it did.

Maybe I am misunderstanding what a PE is supposed to do here. My belief is that he/she designs and specifies much of the structure, inspects the structure during construction to affirm that the plans and specs are being followed, and then affirms same in writing with a stamp added.

Am I wrong somewhere in there? I don't get much involved with structure in my work, but it sure is interesting!

Back in the day, it could be quite a task to be sure that water wasn't added during placement. On important work and big placements we used to have two inspectors available so we could be sure that no one is adding water to the mix while we weren't looking. Some of the truck drivers were very good at hiding it. In my area, I haven't seen that tried in years but I don't often have concrete slabs that are structural and exposed so the push to get a good finish and using water to do it doesn't come up on the structural placements. The exception is large monolithic slabs for shop buildings. I will have help watching those placements. Cheating on the W/C ratio doesn't seem as common as it used to be...here.

BUT. Most Engineers around here don't "stamp" letters that indicate that the work was, actually installed to the specifications. We use terms like we "observed that the installation was in substantial conformance" to the construction documents. Construction is NOT a science and the quality of the construction cannot be assured by observation by the designers. Construction is a partnership of responsibility by the suppliers, designers and laborers. Anyone of the team not up to the task or deliberately cheating can destroy a project and it might not be all that obvious.

It is now pretty common to utilize third party special inspectors. These guys are trained to look at only variation form the plans and are familiar with the placement standards and reinforcing tying and chairs. If it is a large, or critical structure, I will use that process. The IBC requires it for substantial construction.

Quote (Spsalso)

If adding water is all that common, then it hints that a certifying person should be on site at those times to see that that doesn't happen. Or to "certify" that it did. If it did.

From the point of view of a contractor...

I've done some pretty big pours; I'm currently sitting on a site that we are demobing from on Friday after placing roughly 3500 yards over the course of 12 weeks.

There is always a 'certifying person' on site whose entire job during placement is to evaluate the concrete being placed and verify that it meets project specifications - that being the third party concrete testing technician hired by the owner or general contractor. In my experience the EOR is very rarely present for the placement of concrete. I personally have no problem with that at all; I don't view it as part of their responsibility.

Ultimately, as the General Contractor, we are responsible for the actions of any suppliers or subcontractors on the site, including the guys driving the concrete trucks. The concrete testing agency is responsible for clearly communicating to us whether or not the properties of what they test meet the spec, but decisions about whether concrete is placed (whether it tests in spec or not) are up to us.

So, point is, in JayRod's anecdote I don't believe there's any ire to be aimed at the tester; that GC, however, has zero business placing structural concrete. I hope it was flatwork.

As far as final certifications by the EOR; in my experience, they will typically make a few trips to the site (or many if it's a long duration) to spot check things like rebar quantities and placement, final column dims, etc. At the end of the job they produce their as-builts and we get a letter from them stating something to the effect of 'to the best of my knowledge the structure built at 123 Mountain Lane Drive under City of Denver Permit Number XYZ123 has been constructed in conformance with the construction drawings captured by the approved permit'. That letter is always stamped.

That may just be a thing in my local jurisdiction, though, and it may not be a hard requirement. I'm not an EOR so I don't know the rules, but that's what's typical.

For reference, here's the letter from the last high-rise I worked on:

I thought it would be interesting to show some close-up photos of the debris pile that can be seen on a 1920x1280 pixel non-interlaced display while zooming in on frames snatched from high resolution still photos and videos taken by a drone which are then pasted into a PowerPoint document to enable using its powerful zoom capabilities.

The first photo below shows a close-up of the debris pile just before it was removed to clear the floor for foundation studies. The pile shows objects that were seen in the TicToc video and in the vicinity of column 27, but the objects have been pushed onto the pile from their original positions further away and then the whole pile has been pushed closer to the ramp, causing many of the objects to lie in the driving area at the foot of the ramp. Nevertheless, one can see that the recovery workers have used red spray paint to call attention to several objects of interest further down in the pile. One of these objects of interest that is easily distinguished in the photo is the sheet metal top of an air conditioning unit which lies close to the surface of the pile. One can assume that one of the other objects of interest identified by the recovery workers as lying further down in the pile is the lower part of the same air conditioning unit with the radiator, cooling fan, and refrigerator pump. By looking at multiple frames of the video taken as the drone flies past the pile, one can confirm the identification of the top object and a several additional objects nearby as well as seeing down into the pile to confirm that something of interest is below. But it is not possible to confirm the identity of the object below.



The second photo below shows these same objects as they were being uncovered by a back hoe at the bottom of the collapsed debris pile and before they were consolidated into their own little debris pile. Therefore, their locations in this photo are closer to where they naturally fell during the collapse. One can see that the objects in these locations correspond very closely to the objects seen the same locations in the TicToc video. One can easily see the location of columns 26, 27, M11.1, 28, and 29. One can also clearly see that there is a dark-colored car parked in parking space 26 next to column 26. One cannot see a second car in parking space 27 between that car and column 27. But we know from the TicToc video that one is there, and we can see two objects the fell on the hood of this second car; namely, a davit base and what appears to be a hexagonal weight on a rod. The davit base is easily distinguished from an Osha anchor by having no loop on top and by having three triangular reinforcements welded between the base and the central column. Interestingly, a second hexagonal weight can be found on the other side of the red circle. These objects raise the question of what other work was planned or in progress on the roof.



This photo also shows several objects inside the red circle. Closest to column 27 is what appears to be an air conditioner housing with the top opening facing the camera. The housing looks like it has a bulge on the right side similar to some air conditioning units that have a pump to the side of the radiator core. Behind it lies either a second air conditioning unit with the top facing the camera, or perhaps just the inside radiator core of the unit corresponding to the air conditioning housing in front. One can also see what appears to be either column M11.1 tilted to the right or the cross-beam between column M11.1 and L11.1 with its lower end near column M11.1. Either one could have been produced by the air conditioning unit falling between the car and column M11.1 to cause a wedge-like force, which would have caused a high lateral force on column M11.1 as well as a downward force caused by an object falling on the deck. This lateral force might have been what caused column M11.1 to buckle as seen in the TicToc video.

Also in the red circle at the bottom of the pile near the floor of the driving area next to column M11.1 one see a white object with what appears to be windows. But this object is too small for an automobile. While this object has not yet been identified, it has been found that a similar-looking object called a Belle chamber is used for testing roof surfaces for de-lamination caused by hurricane force winds. The chamber is used to apply a vacuum to a 5x5 foot area of the roof while one looks though the windows to observe how high the roofing material rises as a result of the vacuum. The size of this chamber appears to correspond to the size of the object shown in the red circle. Is it possible that such a chamber was being used or planned to be used to test the roof and left on the roof overnight at the time of the collapse? This needs to be further understood.

The objects in the second photo above can be discerned more clearly if one enhances the photo and zooms in further as shown in the photo below. In this enhanced photo one can more clearly see what appears to be a second air conditioning unit facing the camera at a lower position, which may have been the original object seen next to the broken column M11.1 in the TicToc video. Also seen more clearly are the two hexagonal objects that I believe may be weights, and a davit base. In this photo one can clearly see that the davit base is not an Osha anchor because one can clearly see the triangular reinforcements welded between the base and the central column. Finally, in this enhanced photo one can see traces of what appears to be a scaffold between the two hexagonal weights.



One can see that these photos have much higher resolution than a mere “potato camera”. They also have higher resolution than when viewing the same videos using a cell phone or an interlaced 640x480 pixel desktop display.

If one is still skeptical that air conditioning units cannot have fallen from the roof to be found at the very bottom of the debris pile because they are tied down so well by mechanical straps, electrical power lines, and refrigerant lines that they are secure in a hurricane, consider the following. Photo 4 below shows excerpts from the permit issued on the day of the collapse and from an HOA letter describing the work to be done on the roof. These documents show that not only were Osha anchors to be installed on the roof, but also other work was to be done at the same time including stucco repair, air conditioner replacement, and exhaust fan replacement. We also know that a satellite dish was being installed at the same time by an independent contractor. Given that air conditioning units were being replaced at the same time, it is highly likely that some air conditioning units on the roof were not attached at the time, either new ones waiting to be installed or old ones that had just been replaced. These unattached units may have been the ones that fell and were found at the bottom of the debris pile.



Also, if one is skeptical about hexagonal weights being found at the bottom of the debris pile, consider that the permit mentioned that stucco repair was to be done at the same time. Such repair would have required going over the side of the building with a scaffold held by davits. The davits would have required weights to stabilize the scaffold holding at least one man with repair materials, which would have required somewhere between 500 and 1000 kilograms, or over half a ton. These weights could not have been brought up to the roof by using a davit because they would have required getting the weights close to the base of the building over the deck, which was not built for this load. So the weights would have to be brought up by a crane, which had left the building at the end of the work day. Therefore, could the weights have been stored on the roof overnight and in a location close to the edge of the roof where they could have caused a roof collapse? This needs to be further understood.

It sounds like things MAY have changed since the Coral Gables garage and Champlain South were done.

It seems back then that the PE was the person responsible for field inspection. Now there's different people, and the PE is NOT responsible for field inspection.

It's my belief that the general contractor is the main person responsible for the building. But, especially back in 1980, who did the architect and the PE owe responsibility to? I would expect firstly the owner of the building, and secondly the local government (or perhaps the "licensing entity"), and THEN the general contractor.

I could, of course, be mistaken.

With Champlain South, I think the owner and the general contractor were the same person. So if the contractor wishes to do things a little differently, the owner will not object. So THAT'S all covered.

With Coral Gables, the owner was the local government.

So the question may arise, who WAS the person, if any, that was monitoring the pour of the deck slab at Champlain South? Who WAS the person who was making sure the rebar was done right at Champlain South?


spsalso

Quote (MarkBoB2)

I thought it would be interesting to show some close-up photos of the debris pile that can be seen on a 1920x1280 pixel non-interlaced display while zooming in on frames snatched from high resolution still photos and videos taken by a drone which are then pasted into a PowerPoint document to enable using its powerful zoom capabilities.

Those pictures are grainier than my BMs after I’ve eaten nothing but trail mix for a week.

You can’t even hardly make out the text you’ve written.

MarkBoB2,

WOW! Great work..... could you upload the Power Point File, as zooming on this Web Site Sucks as far as resolution.... I am sure there are some nah sayers that will want a 8x10 Glossy for their Office!

BTW< that radiator core is what we in the business call a 'Condenser Coil' on the outdoor unit if in air conditioning mode..... Now that coil takes on another name in heat mode if it is a Heat Pump we are talking about.

SwinnyGG - this is essentially same thing you are talking about but it's based on the formal inspection process that is laid out in the international building code, called "Special Inspections". Under special inspections, the EOR should lay out exactly what gets inspected, by who, how often, and what standard is followed for the inspection. The Special Inspector is typically called Agent 1 and the Materials Testing Agent is typically Agent 2). The EOR can also serve as Special Inspector (depending on jurisdiction). For example on a concrete foundation, usually Agent 1 is going to inspect the rebar size/placement before the pour and the testing agent is the one responsible for checking concrete for slump, air, compliance with batch time to delivery, and taking samples which are later tested for compressive strength. The building does not get its occupancy permit until both the EOR and Special inspector have signed off that construction is fully in compliance with documents.

I don't know much about 1980's building code, and when the "Special Inspections" came into being, but would not be surprised if it was less regimented than it is today.

Quote (spsalso)

I see from pictures posted by Spartan5 back on July 5 that a typical column top poking through the pool deck seems to have been tied to the slab by 4 pieces of rebar embedded in the column, bent 90 degrees, and extending into the slab about a foot.

I haven't a clue how to read what the drawings say SHOULD be there. Is the above what the drawings call for?


spsalso

Not sure it's what the drawing intended to call for, but yes, it calls for it. The pool deck is considered a roof. I cannot find any other details on this.


While I don't think a car would obliterate a column...

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

If I was the building owner, I sure would want stucco repair done before I replaced the whole roof? I would think they would install fall protection anchors, and they haul up Swing Stages to do wall repair, then do the re-roof. But this is Miami?

Scaffolding would be required for swing stages as tie down cables could not drape across the parapet wall on the way to the ground for anchor, nor could the parapet walls be considered strong enough to anchor too. And perhaps weights were hanging off side of building, to counter balance the swing stage?

Quote (MarkBob2)

Also, if one is skeptical about hexagonal weights being found at the bottom of the debris pile, consider that the permit mentioned that stucco repair was to be done at the same time. Such repair would have required going over the side of the building with a scaffold held by davits. The davits would have required weights to stabilize the scaffold holding at least one man with repair materials, which would have required somewhere between 500 and 1000 kilograms, or over half a ton. These weights could not have been brought up to the roof by using a davit because they would have required getting the weights close to the base of the building over the deck, which was not built for this load. So the weights would have to be brought up by a crane, which had left the building at the end of the work day. Therefore, could the weights have been stored on the roof overnight and in a location close to the edge of the roof where they could have caused a roof collapse? This needs to be further understood.

The man behind the BecauseSurfside channel would be the man to ask about that.
The roofing equipment I posted earlier, is rumoured to have been seen left on top of the building overnight. The hot tank trailer as well. It's not unlikely other stuff was left up top either.
Speculation, no facts.

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


Edit:
@thermopile
I'll try and drive up and down the coast tonight and snap some pictures of how they attach scaffolding here.
I'll leave this with you though. Because Florida.

Swing stages by Building Integrity

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

Quote (spsalso)

It sounds like things MAY have changed since the Coral Gables garage and Champlain South were done.

It seems back then that the PE was the person responsible for field inspection. Now there's different people, and the PE is NOT responsible for field inspection.

It's my belief that the general contractor is the main person responsible for the building. But, especially back in 1980, who did the architect and the PE owe responsibility to? I would expect firstly the owner of the building, and secondly the local government (or perhaps the "licensing entity"), and THEN the general contractor.

I could, of course, be mistaken.

With Champlain South, I think the owner and the general contractor were the same person. So if the contractor wishes to do things a little differently, the owner will not object. So THAT'S all covered.

With Coral Gables, the owner was the local government.

So the question may arise, who WAS the person, if any, that was monitoring the pour of the deck slab at Champlain South? Who WAS the person who was making sure the rebar was done right at Champlain South?


spsalso

I think you are asking a question that has a nuanced answer. As a structural engineer, it is my responsibility to design a building that satisfies the code. It is my responsibility to convey that design on construction documents so that design may be executed. The observations of the installation of the work is done by a number of "inspectors". We use special inspectors to observe the placement of concrete (if it is an important structure), the installation of bolts and welds etc. Ultimately, I review all of the special inspectors reports to verify that important aspects of the work were completed, to the best of my knowledge. It is my responsibility to double check that the special inspectors have the qualifications to observe the work before or after it is installed. The code does allow the EOR to perform special inspections if they are qualified to do that. I review EVERY compaction test, EVERY pile load test and EVERY concrete test. I also review the shop drawings. Most of the time, I observe 75% of the installed reinforcing. I observe ALL of the reinforcing where life safety is involved or I have a special inspector do it. But, I don't watch every concrete placement unless it is a large column or a structural slab.

The code has a full section devoted to what aspects of the work require special inspections. That section gets larger every iteration of the code. So, things have changed since the early eighties in the process and the personnel available. In 1979 while I was working as a engineering aid I spent summers crawling all over forms, taking concrete samples, and watching the installation of concrete. I was not a certified inspector as required now but the engineering firm I worked for was serious about observing the construction.

If the firms I worked for in the late 70's and 80's had designed the CTS structure, every single piece of reinforcing would have been looked at by someone from our office. Every single concrete placement would have been continually observed.

But. You ask who is the ONE person responsible for the safety of a building. And, as much as some would like that to be the EOR that just isn't the case. A complex building requires the observations and testing of dozens of professionals. I might direct their work but I am not responsible for it. Does that make any sense?

MarkBob,

Uploading pics to Imgur and then linking makes them a bit clearer, maybe try that..

This platform is rather archaic, have the site Over-Lords considered upgrading? I would imagine with the recent state of affairs of beachfront condos and hotels, this site will get a lot more popular.

@Demented, Who needs a 40 foot ladder, when they have a fork lift!

Demented,
When you say "hot tank trailer", is that what I was calling a "tar kettle"? You showed a pic of one that looked ashy and burned, then I added a pic of a black one beside 2 crushed cars. Are these 2 different objects?

Link
Link

Yes, the tar kettle. There were multiples on the job site is all I know. Having not seen the stuff on the roof myself, I can't be certain if those were the ones he has been referring to, or the smaller ones we know were on the roof. The location of the maintenance spot and the image you posted to me makes a ton of sense. The ash may just be dust that has stuck to the side between moving, rain, being hosed off, etc.

What I find odd is, why would a crew leave the tar kettle on ground level overnight? That is a 100% sure fire way to get it stolen, especially in Miami.

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

It is impossible for me to make a single reasonably informed deduction based on what is shown in MarkBoB2's rubble pile photos.

Literally and figuratively, I'm just not seeing it.

The tide is rising. High tide is 7:05PM today.
https://www.youtube.com/watch?v=l_G-tVRV4yI


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

The last time MarkBoB2 posted the pictures the hexagonal object with a pole protruding from it was described as “the bottom of a deck table along with the mast for holding the sun shade.” At that time what they had identified as a “water main” in the pictures above they noted as a “rooftop ventilation fan.”

It was also pointed out to Mark that blue paint was used to mark objects to be retained while red designated the presence of human remains. Mark has ignored that.

Look at the link to the NIST recovery area in my link at the top of this page. All blue paint.

@Thermopile
Why we're seeing the coating on some rebar. This very likely would be spray galvanizing.


So in essence, the structural repairs in the 90's were injecting some foam into cracks, knocking off loose concrete, painting rebar, and repair mortar? I know repair mortar is 3000k-6000kpsi depending on how long it's been before it dried, but is it actually rated for replacing concrete around reinforcement? This could be what we're seeing in sections of the slab cores that have crumbled and appear to be powder.


Edit: Repair mortar
https://images.thdstatic.com/catalog/pdfImages/10/...

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

Quote (Colostruct)

But. You ask who is the ONE person responsible for the safety of a building.

I am more after who was the person who was supposed to inspect the implementation of the structural design.

Quote:

And, as much as some would like that to be the EOR that just isn't the case.

I think it could have been on these buildings. From reading the Miami Herald article about the Coral Gables building, it does seem so.

Quote:

A complex building requires the observations and testing of dozens of professionals. I might direct their work but I am not responsible for it. Does that make any sense?

I do understand that the inspector of a project does not have to be the designer. And, in that case, it would be ridiculous to hold the designer responsible for the inspector not catching a mistake. Unless, of course, that inspector was "directly deputized" by that designer as a stand-in.


spsalso

PS. Sounds like you take your work seriously. I like that!

@Demented, The permit stuff does not specific where the 20 SF concrete slab was replaced either. Wonder if it was the garage floor?

I saw column rebar that looked galvanized too, which would make you wonder if some columns had very deep repair work done?

I hope MarkBoB2 will post some high resolution pictures, so we can see what he sees.... I can only make out a couple of things from his post, but read the narrative and assumed it was accurate.

@MarkBoB2, Some older Rheem Outdoor AC's and HP's used a rectangular cabinet and the compressor was outside the coil box, but newer Rheem's and all other brands now days have the compressor mounted in the center of the coil box.

This "repair mortar" stuff seems to be specifically designed for overhead work.

Contractor logic.
It's $20 a bucket
It requires no mixing.
It says 6kpsi
I can lay up to just over an inch at a time with no form?
It says corrosion inhibiting?

You mean I can pay a laborer $10/h to stand on a bucket (hey, the mortar comes.in a bucket), chip off some concrete, inject some foam, paint the rusted shit, and have him use a putty knife to smear that shit on and shape it?

Count me in!

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

@Demented,

I saw another permit where concrete crack repair was done with something other than urethane. So this is not the first concrete repair. Appears this garage has been an issue from almost day 1, and the Ocean is not giving up..

#Demented, Did the contractor core sample the roof, before work started?

Quote (MarkBoB2 (Electrical)21 Jul 21 21:09)

then pasted into a PowerPoint document to enable using its powerful zoom capabilities

Could you please attach the PowerPoint file, so we can all zoom in?
(The Image icon destroys any resolution your images had)
Thanks for digging into this...

SF Charlie
Eng-Tips.com Forum Policies

Quote (spsalso)

the person who was supposed to inspect the implementation of the structural design

this was in the "condo structure" permit file from yesterday's uploads.

I have watched enough episodes of HVAC to know that you need a crane to move an air conditioning unit. There isn't going to be an air conditioning unit, not bolted down on the roof, because first your crane is going to remove the old one, then position the new one. Or you position the new in a new spot and leave the old, or remove at a later date.

But, your job hinges on booking the crane in. You aren't going to lift it in place then bolt it in the next day. Thats dumb. The suggestion that you'll have random equipment on the roof unbolted is void of reason. Your HVAC guys will work as many hours as it takes to get the job done. Its not a case of 5pm knockoff time, go home, bolt it in tomorrow.

@thermopile
The repair work to the 01, 02, 03, 4, 08, 09, 10, 11, and 12 stacks?
This permit raises some eyebrows.


As for core samples of roof, I cannot imagine so. I'll have to dig around but core drilling a roof in the rain season is not something I'd expect anyone to do here.
I feel they would have just followed the print and put all trust in the engineer, and ran the epoxy bolts in where the anchors sat, plus or minus 2" from c to c.

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

Residential Package Units weight 400-500 lbs. But Outdoor Split Residential Units weight more like 250-300 lbs. for a 5 ton model. There is some variance depending on Brand and thickness of sheet metal they use. What I saw on the roof was residential units for the Condo's and the commercial unit was much larger and heavier.

I have installed many residential HVAC units, and we do it with hand trucks. The package units, we use a custom dolly to roll them off the trailer and move to pad.

Those Split Residential Units could easily come up the elevator

In fact, I used my mother-in-laws residential elevator to take her new HVAC unit up to the attic.....

Engineer by day, and HVAC was side business. In my prime, I was lone ranger on installs and did it all with muscle......

@Demented, You must be talking about all the balcony repairs when you refer to those stacks, with the long punch lists for each stack??

From around 2002 with the exploratory excavation of columns to find and repair rebar corrosion. I don't have documents in front of me right now though. I could be blurring two things.

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

And the Conspiracy Plot thickens............

Ah they mention repair of delaminations of balcony's.....

PLEASE STOP POSTING IN THIS PART 7 PLEASE
Please allow me to move the discussion to Miami Beach, Champlain Towers South apartment building collapse, Part 08, Thank-you.
Someone Please close this post to new postings, or message me how to do this, Thanks.

SF Charlie
Eng-Tips.com Forum Policies

Conspiracy?
*puts on Inconel718 hat*

And yes, I was blurring two things. Dumbdumb over here has to go find what he was referring to with the column exploration. It may not have even been work that was done yet. I got distracted by requirements over piles and core drills in the balcony repair permits and jumped to assumptions.

Quote (BecauseSurfside)

Because Surfside
​I will post a timelapse soon that shows where the water comes from

​There will be a full moon on Friday. Tune in at 9 am for high tide; and 11 to 1 when the tide is going out. Let's see if the water is higher at 9 than it is at 1pm

The slab really is filling with water with the tides.
This will be interesting.

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

At the request of SFCharlie I have uploaded a PowerPoint file with this submission containing the four images shown in my last submission. Hopefully this will improve the resolution of the images. It will also allow removing some or all annotation over the images to permit viewing any objects obscured by the annotation.

For anyone without a PowerPoint application, I suggest copying the JPG or PNG images from my last submission using your computer's COPY function and then pasting the copied image into either a Word or PoserPoint document before viewing. Both of these applications have zoom capability. When I did this on the images from my last submission, the resolution was only slightly degraded, probably because of using the Microsoft Paint application to create a JPG or PNG version of each image. If you still find the image resolution unsatisfactory, then it's likely because your computer display is not good enough.

• https://files.engineering.com/getfile.aspx?folder=8aed0cdf-ceb9-420a-ae88-d

The conspiracy thing was just it seems there have been lots of repairs of damaged concrete on this project over many years, so only a real dull Condo owner, would not realize something ain't right.... All the cosmetic work just covers up the cancer........I think they said one owner was a structural engineer.....

I assume records would show a lot of turn over of owner's over the years...... Some stayed long term, but I would imagine the more savvy ran...

Hard for me to imagine folks in Condo that knew engineers or builders did not ask what they thought of water intrusion.....

Quote (Quote:



And, as much as some would like that to be the EOR that just isn't the case.


I think it could have been on these buildings. From reading the Miami Herald article about the Coral Gables building, it does seem so.)

There is also what is called structural observation in section 17 of the building code. These observations are performed by the engineer of record. Structural observation is just a periodic site visit. Example, just before pouring the first deck, the engineer comes out and takes a look at it. This is in addition to special inspection and city inspection. Special inspection does not replace inspection by the governing agency.

Structural observation is only required for certain risk categories, seismic areas and high wind areas. I imagine Miami qualifies as a high wind area. I am certain special inspection was not a requirement at the time CTS was built. Structural observation was part of the building code then but that doesn't mean the governing agency required it.

My best guess, Miami, 1980, the developer had just given the city $200,000 for sewer improvements..... I doubt there was meaningful inspection.

It's events like this that occured pre early 1980's that led to special inspection requirements being added to the building code.