Quote (Reverse_Bias)

I could imagine it smelled like everything.

Exactly. Anyone who has ever helped sandbag during a major flood, as I have, can tell you that floodwater has an indescribable and potent smell. Raw sewage, all the petroleum spills that ever happened in the area, and rot/death combine to make a heady, nauseating stench. Tossing in Tesla and other car batteries would make it extreme.

All the Stachybotrys hiding in the darkness of the waterlogged structure that was violently thrown out into the open.

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

Charlie, I always get nervous when you end one chapter and start the next one because I see this message "PLEASE STOP POSTING IN THIS PART 14 PLEASE" and I think it's directed at me LOL!
"

Jeff,

It's not you. It's us.


spsalso

If they did not use sheet piles I could actually imagine an instance (Not a very likely one) where the foundation was undermined. Any kid that has tried to build a sandcastle knows that it is really hard to dig a hole on the beach. Sheet piles and big pumps are necessary to do basically anything in this area.

The lithium batteries in a Tesla do have a really bad smell. The fumes have an effect on mental well-being. Exposure is unhealthy.

Quote (Keith_1)

If they did not use sheet piles I could actually imagine an instance (Not a very likely one) where the foundation was undermined. Any kid that has tried to build a sandcastle knows that it is really hard to dig a hole on the beach. Sheet piles and big pumps are necessary to do basically anything in this area.

Steel sheet pile walls have a life expectancy of what, 40 years in a highly corrosive environment before they're at 10% uncorroded mass?

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

Quote (AutisticBez (Computer)29 Nov 21 06:1)

Thanks for the info. All the sulfuric acid in the rest of the cars cannot have helped...

SF Charlie
Eng-Tips.com Forum Policies

Sulfuric acid is odorless. A single Tesla is also only going to contain ~40lbs +/- 5lbs of Lithium metal.
The majority of the scents would have been for the most part, building materials, and not automotive. Buried under multiple floors of concrete, I doubt even the smell of burnt dif fluid would have been getting out the rubble pile any time shortly after the collapse.

@Demented - if the piling under that perimeter wall had degraded so it was no longer providing the proper lateral bracing for the deck, could that have resulted in the collapse? I don't think so, that would surely have pulled the deck away from the building and you'd see columns pulled over, not punched through.

Waterflow under the foundation is the issue at hand with that. Nothing to do with support for the deck/wall connection.

Quote (40 years in a highly corrosive environment before they're at 10% uncorroded mass?)

Life can be much longer with proper coating systems or cathodic protection. A design sacrificial surface can be included.

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

-Dik

The Disappearance of 87th Terrace and How it Relates to Surfside Collapse - Lawsuit Analysis Part 2

https://www.youtube.com/watch?v=1U0D9rCaLvY

Quote (dik)

Life can be much longer with proper coating systems or cathodic protection. A design sacrificial surface can be included.

What would that likely bring the maximum life expectancy to, and serviceability of the anodes?

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

Tesla batteries contain Li Co Ni & Al oxides and altogether weigh 900lb. The electrolyte may be a range of possibilities (not suggesting its a State Secret, just more complicated than I have time to research) but the following paras:

"Most of the electrolytes used in commercial lithium-ion batteries are non-aqueous solutions, in which Lithium hexafluorophosphate (LiPF6) salt dissolved in organic carbonates, in particular, mixtures of ethylene carbonate (EC) with dimethyl carbonate (DMC), propylene carbonate (PC), diethyl carbonate (DEC), and/or ethyl methyl carbonate (EMC) .
...
Organic fluoro-compounds are one of the most promising electrolyte solvents for high voltage condition, because fluorinated molecules have higher oxidation potentials due to the strong electron-withdrawing effect of the fluorine atom .
"
suggest you'd be a brave person to bet on what it will smell like under duress.
(quotes from here: https://www.sciencedirect.com/science/article/pii/... )

The only Tesla we have documented proof of was parked under the uncollapsed southwest corner of the building.
It 'may' have caused some fires after the demolition but was certainly not part of the initial collapse.

New Miami Herald article

Champlain Model Explained

https://www.miamiherald.com/news/special-reports/s...

In the Nov. 30 Miami Herald overview of their collapse models, they draw two conclusions that are at odds with the witness statements documented since July 27 in the Timeline of Witness Statements. Journalism being what it is these days, their witness narrative is likely to be taken as the de facto standard despite these discrepancies.

1. The Miami Herald ignores the late Elena Blassner’s (1211) report of unusual loud noises the morning before the collapse, and also Chani Nir’s (111) statement that she heard banging as soon as she got home at about 11 PM. Instead they start the narrative clock when Sarah and Gabe Nir get home around 12:30 AM.

2. The Miami Herald states that the loud crash heard before the deck collapse occurred at 1:14 AM instead of 1:10 AM. This is in conflict with multiple contemporaneous statements by Sarah Nir, who was using WhatsApp at the time and looking at the clock. She said in several interviews that the first crash happened at 1:10 AM, and that she then worked up her ire and went to the lobby at 1:14 to complain to Security Guard Shamoka Furman. Shamoka has never stated a time of that crash, which she also heard in the lobby.

I am not updating the Timeline with the Miami Herald’s slightly improved narrative. Both NIST and KCE have access to the Timeline, and I believe it should be maintained as accurately as possible no matter what the Miami Herald writes five months later. These discrepancies are not based on new information; they are instead, in my opinion, editorial decisions to avoid having to muddy a clean narrative with outlier information.

Seems they've found a source of WAG's and are running full steam with it.

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

Demented

Their model "Slab self-weight of 150 pounds per cubic foot (pcf). (Assumes 9.5” slab everywhere, as detailed in 1980 structural drawings.)"

Wasn't it determined that was only up to the 8th floor, the slab thickness?

Does their model even go that high? I didn't get the best of read on it, but to me it read as though they've only modeled specific locations to run simulations on, or only up to the lobby level. Seems to me they've gotten impatient and just decided to go with one set of drawings and ignore as builts. I don't know, doing knowingly wrong simulations doesn't sit right with me.
Per 1980 plans, Basement is 9", Lobby is 9.5", 2nd to roof 8".

Edit:

2nd not boxed in red is taken from an adjacent page of the same 1980 revision plans.

Why they no read?

Looks like the Miami Herald’s story

The Herald built a computer model to explore how Surfside tower fell. Here’s what it showed

is no longer behind the paywall.

Is a Pulitzer Prize in their future? Or will the NYT fight back? Stay tuned…

"The Herald built a computer model..." Because THIS is what reporters are good at and should be doing.

There were lots of ways to write an accurate headline here and The Herald wrote the worst one. Why not "The Herald commissioned a computer model..."???

============
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

I think the Herald article rejects it's own computer model in the first few paragraphs
The witnesses described the collapse sequence as a three-part failure, each with distinct sounds
Then from the model they conclude after the two pool deck collapses, the first floor of the building caved in just before the building fell. That would be 4 collapses, unless the building fell instantly after the first floor caved so witnesses never heard a gap. Another thing that makes the first floor cave in theory not that appealing is that the 711 ringcam showed a warping wall prior to the collapse and 611 reported a crack opening up. This indicates something was wrong with the entire X11 stack, not just the first floor.


Speaking of the X11 stack here's another reason to doubt the model.
Finally it shows it is unlikely that the collapse of the building initiated under Unit 111, as has been suggested, since the additional structure there protected that area of the slab; it is more likely that the damage to the level-one slab within the tower propagated north and east from the gym and the slab-to-core wall connection.
That "additional structure" was laying on the ground in the TicTok video if that's what they're talking about.

They admit it's a very incomplete simulation, so I'm taking it with a grain of salt.

Everyone loves a model and maybe this is a half-step forward IDK, but what would be a real step forward is more interviews to fill in gaps where possible, and more heat on officials to release basic data. Both of these things are more in a newspaper's wheelhouse than detailed engineering from sparse info. I suppose publishing this might possibly chisel loose something new, we'll see.

Quote (Reverse_Bias)

… the two pool deck collapses,

I don’t see the Herald claiming there were two deck collapses. Instead, they state,

“At 1:15 a.m. the western half of the pool deck and part of the valet parking area collapsed in one loud cascade of concrete.”

Quote (MaudSTL)

I don’t see the Herald claiming there were two deck collapses. Instead, they state,

“At 1:15 a.m. the western half of the pool deck and part of the valet parking area collapsed in one loud cascade of concrete.”

Yeah that was poor wording on my part. Nobody knows what the first "wall collapsing" noise was.

If anyone owned a Tesla where would they charge it in that parking garage?

One of the many EV rapid charging stations located up and down Collins would be my guess.

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

Can't wait for the CTS Lego set. We can test out all the various theories, replace some of the pieces at key areas with cheap Lego knock off brands from China. Should be an accurate simulation.

If you ask me, I think a combination of failures caused this.

First, the pool deck disconnected with the south wall because old damaged rebar from decades of condo board not maintaining it. Maybe a forklift drove on it, unconfirmed. Maybe 87 did it.

Then the unsupported planters near valet went due to someone forgetting to put a beam under them when converting to new design. Then tarpaper fell from the roof falling through a crack in the pool deck dropping next to a car causing it to swerve and hit the missing column.

X11 felt sorry for the column and fell on the car for revenge. End of story. Did I miss anything?

Screw LEGOs, we need K'Nex sets.

Foundational issues. I really think there's issues with the piles, especially the tension piles.

> The Disappearance of 87th Terrace and How it Relates to Surfside Collapse - Lawsuit Analysis Part 2

Interesting stuff. Thanks for posting the link to the next video. It's pretty clear that the construction of 87 Park is extremely dodgy, and probably illegal in the way they acquired the street land. Certainly at least deeply unethical, since they got all the relaxations in the rules on the basis that they were going to keep the existing hotel and then they turned around and changed everything.

It's much more difficult to prove that their construction caused CTS to fall down though.

The Miami Herald is going after the project next door. ‘The city will help us.’ Miami Beach took cash, fast-tracked tower on Champlain’s edge

>>>>>Edit: Looks like it’s behind the paywall after all. Here’s a link to the archived version.

So...have I got this right?...Surfside's quick ask-no-questions post-facto-approved questionable building was possibly compromised by Miami Beach's quick ask-no-questions post-facto-approved questionable construction and all that will be left to consider, after the lawyers have all finished, is how to split the remaining 38c among the surviving families?

The County's crime-scene tape is making more sense now.

I need to get something straight too.
Is this pile driving damage causing vibrations all hinging sheet pile driving, and only sheet pile driving? I think I've been wrongly assuming they've also been talking about regular ol' impact hammering of piles, not just the gentle foot massaging vibration driving.

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

Quote (Demented)

From the Building Integrity video I got the impression it was all vibration of sheet piles they were upset about, but the details will be in the text of the plaintiff's court submission, if you want to plough through it.

I made it about 3/4 of the way through, there's a lot of BS to sift through, but seems the main complaints do ONLY revolve around brief vibratory sheet pile driving and the use of a tractor crane (Assuming they meant crawler crane but have no idea as to anything they're arguing). Complaints over continued construction noise between 8AM and 5PM, Sunday-Saturday also being their main bit of evidence as to those involved in the construction of 87 Park ignoring warnings that will damage CTS.

The suit clearly states NV5 inspected CTS in 2016 and documented ALL existing damage to the CTS structure. However, the suit fails to show any of this evidence and only shows Morabito photos from 2-3 years past showing the damage we've all seen already. Those NV5 photos sure would be nice to see, as according to the suit, they did contain photos of existing cracks in drywall of interior units and existing stucco damage.

I thought there was more to it, but nope, nothing. This suit will either be dropped, or defeated easily. The complaint seems to focus around certain verbiage as evidence of this being damaging work, not actual proof damage was done.

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

Part 3 of Building Integrity’s Josh Porter’s analysis of the lawsuit against the sheet pile driving neighbor. https://youtu.be/sqvqY4H_2hI

After viewing Episode 3:

Mr. Porter says, in regard to a photo of the CTS wall, that "...you're missing sections of block..." On examining the photo, the above-grade wall does seem to be resting on concrete block. Is this below-grade concrete block also supposed to be holding up the now-fallen pool deck? If it is not, why would it's condition matter? Actually, it appears that the concrete blocks did a pretty good job, as the above-grade wall is still standing. Even with those missing blocks.

There is a comment that the walkway was "pitched", and that view was supported by the fact that the gravel was below the level of the walkway surface. Is the walkway itself "pitched"? If it is, why is not the slope of that pitch mentioned somewhere? If someone had put another couple of inches of gravel there, apparently the area would NOT have been pitched. At least, following the logic I heard. Is that missing two inches of gravel the reason CTS fell down?

This area, being outdoors, will be naturally wet during inclement weather. There appears to be an assertion that the CTS wall was made "extra" wet by the construction of this path. I would like to hear that concept developed by the CTS people.

I am curious at the level of water intrusion (in this outdoor place) over the last 40 years. Was that area of the wall bone-dry until construction next door? Was it wet? How wet?

The lawsuit apparent asserts that the pool deck became detached from its supporting wall (caused by the poor construction practices nextdoor). I note that there were no photos or description of the failed connection. What was supposed to keep the pool deck attached to the top of its supporting wall? What did it look like after the fail?


spsalso

I am not sure why this story is being detailed now. However, USA Today has published a long piece about the effort to save Valeria Barth (204.) Here is an archived version of Surfside rescuers heard her voice, tried for hours to save her. Then officials buried her story. The Timeline has included the basic facts of Valeria’s survival and the failure of her rescue since July, so there will be no Timeline updates based on this piece.

>>>>>Edit: Because of its helpful graphics, I added the link to the archive to the Timeline on Row 63.

My question is, who owns the pathway? It's technically owned by 87 park right? So, they did work that left part of the wall vulnerable to water intrusion?

As for the gravel, wouldn't this automatically be the lowest point because water can sink into the gravel? The lowest point would be under the gravel at the waterproofing? If it had waterproofing.

I think there is a good chance the failure started at the south wall. Water intrusion at the wall could definitely have gotten into the rebar.

As per NV5, I guess this might be introduced as evidence. But still, they never bother to inspect the wall? Check for damage? It's also very possible to have damaged the wall during works.

This is also perhaps the only possible target of a lawsuit to get back any money.

I was following the Herald's approach laid out in their article up until I read this:

"While inspection reports indicated that the pool deck had suffered potentially debilitating water intrusion, concrete degradation was not factored into the model. The concrete was modeled at full design strength."

I can see why they approached the problem this way. They don't have access to the site materials. They'll get some useful baseline numbers from their analysis. But in the end all their work will likely have to rerun. Their analysis focuses entirely on the rebars (missing or degraded) as being the sole source of the failure. I believe this is a flawed approach.

@TheGreenLama, another major flaw is that the model is based on approved plans rather than as-built, because of course they also had no access to as-built plans or the ability to prove/disprove structural flaws such as the failure to resupport the step between the parking and pool decks that Jinal Doshi discovered, etc.

I'm not sure that I follow the heralds train of thought. Their edge conditions either lead to or start with a 1.5 inch downward deflection of the south edge of the slab. That would be to say that the continually supported south edge is weaker than the thinly supported column connections. I also struggle with the concept of the south edge slab rebar shearing.

It may not be entirely possible to know if the failure started at the south wall, but I think it's worth considering. And maybe they know more about this then the public. But question, if they knew there was a problem at the south wall, why didn't they do anything about it?

Here is something else, the original street would have had drainage. This is something the path didn't have.

The pool deck failure has 4 main possibilities that I see:

1) It could have started at the south wall from weak connections and propagated north toward the building.

2) I tend to lean toward the idea that it started at the building and propagated south toward the wall. Ground zero would be the planters outside the Nir's condo Unit #111, because that is where most of the previous damage and repairs and issues were reported, the palm trees were there, root balls poking through drainage pipes, overweight planters, etc.

3) Others have proposed that the fact that there was a beam in the design that was removed over near the covered above-ground parking, that the collapse could have started there by the above-ground parking and propagated in all directions.


4) Then finally is the other theory that it started up against the shear wall/gym area due to the weak attachment of the pool deck slab to the shear walls.

One thing most of us agree on is that based on load calculations and the theory that this pool deck was near 100% load as-built, combined with weakened and degraded concrete no longer rated at the as-designed PSI, this was one large punching shear waiting to happen. So no matter where the pool deck failure started from and propagated to the other ends, all it took was one spot for it to separate, and once you have that, the slab design meant to add support to the structure became its Achilles tendon, actually dragging the rest of the pool deck down with it in whatever direction it propagated in.

Demented, stated that "Steel sheet pile walls have a life expectancy of what, 40 years in a highly corrosive environment before they're at 10% uncorroded mass?"

My response is as long as the concrete "retainment walls" cure who cares what happens to the sheet piles because they are basically designed for zero compressive load. Sheet walls are nothing more than a means to an end, be it to excavate for the purpose of forming and pouring caps, grade beams ,under-grade slabs or whatever else. When you can dig to the water table with a hand shovel, there is no other choice than to put in sheet walls, drill a few point wells, and dewater. Trust me, on the beach it is like I said, "a kid trying to build a sand-castle on the beach.

You as dangerous as the people that are responsible for the loss of so many lives. This building failed due to a complete, and in my opinion negligent failure to maintain the membrane.

Sheet piles are also used to stop/slow/divert the flow of underground tide water down here. One of main reasons we drive them (and leave them with a 30 year inspection) and have been in newer ocean front/water crossing construction, especially in certain tidal and reclaimed areas and those that have been subject to massive land erosion.
Heavy hot dip galvanizing with tar coating is awesome for keeping that water out for a long long time, but not many people do that.

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

Demented,

In this area there is absolutely no bedrock, it simply does not exist. In this coastal area there is absolutely Zero reclaimed land. What we do have is extremely course sand, hence friction piles are par for the course.

The water table is at best 7 feet below grade, if you attempt to excavate 20 -25 feet as in this structure it would be physically impossible to do the excavation without sheet piles and dewatering. I'am trying to tell you that this is a practical construction method and not a structural design issue.

Like I said you are dangerous

Demented,b

Wellpoints and multiple 300hp pumps, with containment booms / sheets for environmental containment are simply what it takes to do the job. There is alot of water that you have to get rid of to do anything below grade in SE costal Florida. There is a really good reason that homes do not have basements in the area, and that there a very few undergrade structures in the area. I do know of one attempt for a multi-story underground parling ~*50ft currently under construction, and it is a 18 month, 20+ million cluster f@#k.

Jeff Ostroff (Electrical)14 Dec 21 16:37
The pool deck failure has 4 main possibilities that I see:

1) It could have started at the south wall from weak connections and propagated north toward the building.


The "wall" is not a compressive member, it is strictly a retainment element, the load is on the piles

2) I tend to lean toward the idea that it started at the building and propagated south toward the wall. Ground zero would be the planters outside the Nir's condo Unit #111, because that is where most of the previous damage and repairs and issues were reported, the palm trees were there, root balls poking through drainage pipes, overweight planters, etc.

The planters, the grass, the pavers, all set on top of a piece of concrete, the membrane between each of those elements led to the observed spalling, and the eventual failure of the beams. A building that losses the trasfer points of load will fall down. The only failure point is the membrane.

3) Others have proposed that the fact that there was a beam in the design that was removed over near the covered above-ground parking, that the collapse could have started there by the above-ground parking and propagated in all directions.

Who really cares, one single point of weakness is not an issue, especially when the load was successfully transferred for 40 years



4) Then finally is the other theory that it started up against the shear wall/gym area due to the weak attachment of the pool deck slab to the shear walls.

Simply confuse

Keith, you clearly have no idea what I'm talking about.
I know what piles are, what sheet piles are, and what they're used for. I don't think anywhere I said they're a bad or unpractical idea. Unpractical to service if their use is also to block waterflow from the lower foundation and piles, but that's the only drawback. Most buildings are knocked down and rebuild before anything ever becomes an issue though on the projects I've been involved with that required them for that use on the shore. I've only once see a property drive new sheet piles, but this was after some pretty bad land erosion and signs of settlement closest to the shore after a hurricane, as well as on a manmade island. We have lots of those artificial islands; not sure how you can say we have no reclaimed land here.
When water starts to flow through and erode the sand around the PIF, pre-cast, steel casing, sheet, H, or composite miles, you start to lose your friction. On a building with documented settlement with horrid pile plans with pile changes after ground breaking, it's hard not to consider issues with the piles, especially when we know water is easily flowing under the property.

"This building failed due to a complete, and in my opinion negligent failure to maintain the membrane."
I'm curious who you blame for the failure to maintain the membrane.

The sad thing is I don't think yuu know what a membrane is?

A barrier. In the context in which you're referring, the waterproofing membrane on/in the deck and exterior of the building if you consider the latex exterior a membrane. The one that was repaired/replaced 2 or 3 times. Curious who you blame for the lack of maintenance. I know who I see fault in with the membrane. Go on now. Mr. Dangerous wants to know.

Lool...*waits for the name change*

Wth is he on about?...

Jeff Ostroff

I'd go with #4 being the closest IF their scenario has any merit, their model is lacking many factors.

Here’s an archived version of the Miami Herald’s Grand jury: After Surfside collapse, require frequent inspections, stricter association rules.

Ok, this a pointless conversation. Gooday

Just off the press...

https://miamisao.com/wp-content/uploads/2021/12/GR...


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

-Dik

About time they recommend structural guys do the structural inspections and the sparkys do the electrical stuff, not just any PE, and want to punish those who lie on inspection reports.

"36. We recommend that DBPR amend its practice and stop the dismissal of complaints which contain both criminal violations and regulatory violations."
That'll be a cold day in hell.


There was a meeting yesterday regarding a motion for the Town of Surfside to be an inspecting party allowed to store debris and perform invasive/destructive testing.
https://ctsreceivership.com/wp-content/uploads/202...
"19. The Court has recognized the Town as a potential defendant and as an interested governmental agency, and has treated it as such with respect to site access."

Uh oh. Potential trouble in paradise? According to the Miami Herald, it turns out that the Mirage, which is post-tensioned, shares the same architect (and very similar design) as CTS. It has a history that has included broken tensioning cables, large cracks in the deck, cracks and flooding in the garage, long-standing maintenance and condo board issues. Allyn Kilsheimer of KCE and other engineers are interviewed.

Here is an archived version of the Miami Herald’s A lost ‘Champlain’ tower languishes in Surfside. Residents don’t know if they’re safe.

Battle lines are being drawn. It’s going to get very ugly. Per the Miami Herald, United in grief, bitter legal battles now divide Surfside collapse survivors and families.

Seems to me there is a confusion between emergency relief, insurance, and compensation. Heirs don't need emergency accommodation and new pajamas, but survivors do. Owners or their estates are due the insurance they paid for and whatever saleable value remains, less (I guess) whatever culpability they can be shown to have for the disaster (hence I'm guessing recent posts here about the sacred membrane). Non-owners or their heirs are due at least whatever public liability insurance the building carried. What constitutes compensation per se I don't know. Surfside forking out for approving the thing in the first place? Some state-wide fund from gummint, or levied on the condo business? Grief seems to get deeper the deeper the pockets the compo fund has access to. Stinging Morabito, absent evidence of smoking gun malpractice, will have the effect of making it hard for other condo boards to get professional advice right when they are needing it, which is not helpful.

One thing's for sure - lawyers are going to make a fortune.

Politicians like to panic, they need activity. It is their substitute for achievement.

The Miami Herald has compiled their reporting to date in an excellent infographic called House of Cards: How decades of problems converged the night Champlain Towers fell. I'm still going through it from the witness statement perspective.

So far, I see that they still start the clock at 1 AM. This means that they continue to ignore the loud cracking sounds heard 22 hours earlier in 1211, and the fact that Chani Nir in 111 was hearing banging starting at 11 PM. So far, the only new witness info I found was the definitive statement that the time stamp of Cassie Stratton's call to Mike Stratton was 1:20 AM...this is the first time I have seen this in writing, so I will update the Witness Timeline with that info. If I find any other new witness info, I'll edit this post and the Timeline as required.

>>>Edit:
I went through the infographic a couple of times. The MH is sticking with their artistic license as mentioned above and also in regard to the time when Sara Nir went to the lobby after hearing the so-called first collapse. In all her initial interviews, Sara said that crash occurred at 1:10 while she was WhatsApping, and she went to the lobby at 1:14. I don’t think this makes any difference from an engineering perspective, but I do think it is inaccurate to claim now that the Nirs heard the first crash at 1:14 when they actually heard it at 1:10..

Another example of artistic license is where they show the crack running down the wall in 611. I can find no statement by Ileana Monteagudo to describe which living room wall cracked. Yet the infographic depicts it on the east side. I would like to see that confirmed by Ms. Monteagudo herself. But for now I still don’t think we actually know which wall developed the crack.

Other than the Stratton call time stamp, I didn’t see anything new or worthy of a Witness Timeline update. Although it makes no engineering difference, I was amused that they added something about the Nirs encouraging Shamoka Furman to join them in leaving the building…that’s the first time I have seen that claim. I feel skeptical about it, considering that Sara did nothing but yell at Shamoka in the lobby. Maybe it’s a little revisionism to make up for Sara’s repeated statements of having had to tell Shamoka what to do, e.g. demanding Shamoka call the cops on whoever was doing construction in the middle of the night, commanding her to pull the fire alarm and call 911 after the deck collapsed (insisting she had to call the event an earthquake,) and having to provide the street address.

I always wondered why her husband Mike was so adamant repeating that he distinctively recalled the call happened at 1:30 went the building had already collapsed at 1:22. So I wonder how they got this new timestamp

The infographic states that the time stamp came from “call logs.”

I mentioned to one of their reporters today about the lady complaining the day before about the creaking concrete building. I too wonder why they never mentioned that. They also did not mention the pool guy seeing the spalling 36 hours before the collapse. My early videos on this mentioned it, and it was in the news, but the spalling was "man-made", as what he saw is what Morabito told the contractor in 2020 to scrape off the Korbel of the pool in 2020. BUT... the pool guy saw pooling water in space #78 at this timestamp of 36 hours before the collapse. That might be of importance, and everyone has left this detail out since then. It was only on the news around June 25 and June 26, then quickly forgotten.

Joint testing at last.

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

• https://files.engineering.com/getfile.aspx?folder=e395bdcf-9c52-4550-be01-d

Looks like the judge knows how to write.

I see that the ONLY .gov's to receive this were miami-dade.


spsalso

A new study of sea level rise associates the c-word with the CTS collapse.

https://www.palmbeachpost.com/story/news/2022/01/0...

Here’s the abstract, which includes a nice tidal graph annotated with hurricanes. https://www.sciencedirect.com/science/article/abs/...

The abstract states in part, “Historical trends in the elevation of sea-level, King Tides, and hurricane storm surge quantified between 1994 and 2020 reveal the number of times sea level rose to elevations above the building's basement floor increased from an average of 244 per year between 1994 and 2006 to 636 from 2007 to 2020. This is attributed to a 3-fold increase in the rate of relative sea-level rise that occurred after 2006.”

Anyone recall an image anytime where a rebar cage sprouting from the garage floor was rusted out? In distance shots some looked incomplete vs others, but in every close-up I recall there was recent surface rust only. The rise of sea level is one of those "gee, it can't have helped any" vague factors that - for this collapse specifically -could be either significant or a red herring.

Quote (AusG (Petroleum)10 Jan 22 01:47)

a rebar cage sprouting from the garage floor was rusted out? In distance shots some looked incomplete vs others, but in every close-up I recall there was recent surface rust only.

I vagally recall an NIST photo of an intact portion of a column still attached at the slab, but bent and with what looked like solid rust at the central square of the remains of the connection to the slab.

SF Charlie
Eng-Tips.com Forum Policies

Two new videos:

Building Integrity

Zeroing in on the Initiation of the Surfside Collapse
https://www.youtube.com/watch?v=YZFzVlpPSyg

Jeff Ostroff

Best Condo Collapse Theories: Me Or Miami Herald House of Cards?
https://www.youtube.com/watch?v=NySfow1ugm0

Be sure to read the comments on the above video, as Dawn Lehman joins in on the commentary as does Mike Bell.

Wouldn't rebar rust anyway after sitting outside for a few weeks in the brutal humid weather and rains that we had down here in Miami?

Quote (Optical98 (Computer)13 Jan 22 01:39)

Building Integrity

Zeroing in on the Initiation of the Surfside Collapse
https://www.youtube.com/watch?v=YZFzVlpPSyg

Youtub's Building Integrity gives a well reasoned explanation of why the deck collapse requires rebar failure in tension at the south perimeter wall.

As I understand it, the theory from Building Integrity is that the rebar connections into the pool deck slab along the south wall of the perimeter bathtub had been compromised. He points out a few early photos showing that the rebar had simply fractured (as opposed to 'zippering' from the concrete), claiming that this supports the idea that the reinforcing steel in that area had been eaten away due to long-term corrosion. With decent close-up inspection of the fractures made shortly after the collapse, it would probably be quite easy for investigators to determine whether the degree of corrosion was extensive enough to conclude that it must have started well prior to the collapse. I don't know how quickly rebar exposed to Surfside weather will rust into nothing, but I'm inclined to think that -- even after a month or two of such exposure -- the remaining cross section of good steel won't be very much smaller than at the start. Of course, any corrosion occurring at the bondline between rebar and concrete will weaken that bond and encourage a zippering kind of failure but not necessarily a tensile fracture of the rebar itself.

Assuming that Josh's theory about the slab failing in tension at the southern boundary is correct (and it sounds feasible), on failure, I would expect the southern edge of the slab to jerk away from the wall on failure, but surely it would move no more than a fraction of an inch - Josh estimated 0.4" to 0.5". Had it moved even a few inches, it would surely have taken out all the columns around the upper level parking, but they all remained undamaged.

How would that miniscule movement bring down the building on the northern edge of the slab?

I believe that Josh is suggesting that the collapse could have been precipitated by something as "benign" as the normal day/night loading cycle. For this to work, we must pre-suppose that the pool deck was teetering on the hairy edge of collapse for quite a while and that those thermally-induced stress cycles in the corrosion-weakened rebar finally produced a fatigue fracture on that fateful night. With the southern edge no longer tensioning the deck (the analogy of those tug-of-war guys letting go of the rope), additional load would have been suddenly transferred onto the columns that was sufficient to initiate the punching shear failures which led to the building collapse. As I recall, there were some load-transferring beams near the building footprint which -- in response to the collapsing pool deck -- could exert a strong moment onto several critical columns supporting the building. This aspect of the design has already been criticized on this forum because it allowed a collapse of the pool deck to threaten the whole building.

So groundwater infiltration at the top couple of feet of soil would cause the rebar to fail at this location? Wouldn't that have called for some sort of waterproofing membrane? Or is such infiltration so unusual that no one thought to do it?

I wonder how long the building would have stood if it had been properly constructed, but keeping the water infiltration at this point. The expansion/contraction at the joint would have remained the same, and the damage to the rebar would have remained the same. Of course, the deck presumably wouldn't fall down. So maybe just a nasty repair job at the failed joint.


spsalso

The 2018 Morabito report describes "failure" of the waterproofing membrane that would have normally protected the structural slab of the pool deck. I don't recall if they mentioned it in their report, but one of the big contributors to that failure (aside from the general lack of maintenance) was a standing water situation caused by the defective design ("Gee -- looks like we forgot to include any drainage slope"). So I think there was a long-standing problem with moisture and chlorides attacking the slab reinforcing. Along the southern edge, that already bad situation could have been made even worse by the construction at 87 Park. At least that seems to be what the lawsuit is alleging.

To be clear, isn't the waterproofing membrane for the pool deck laid out in a flat, horizontal manner, so as to keep water from penetrating downwards?

Here, we're discussing the water coming in from the edge, very likely below the level of that membrane.

spsalso

Quote (spalso)

To be clear, isn't the waterproofing membrane for the pool deck laid out in a flat, horizontal manner, so as to keep water from penetrating downwards?

Yes, but no waterproofing membrane is waterproof indefinitely.

Waterproofing membranes all have some level of permeability; the membrane works because the permeability is low enough that water has time to drain away before penetrating the waterproofing system. If the system has ponding on top of it continuously, for an indefinite amount of time, eventually water is going to penetrate. Once that water has penetrated, it will take a similar long amount of time to disperse (because it's either absorbed into a substrate or it collects and must propagate back through the membrane in the other direction).

In other words, waterproofing a horizontal surface without providing any provision for drainage at the level of the membrane is a recipe for eventual failure if the local climate means standing water for long periods of time.

So 87 Park would have had to do something to increase the leakage through the pool deck membrane, and that failure would have had to have been where the concrete span took off from the wall. Quite an accomplishment from an adjacent property.

The fail point under discussion is right under the inside of the above ground wall, right? What if water, perhaps pool water, leaked through right there?


spsalso

I see zero evidence that there was any vertical waterproofing on the southern wall like they do up north on foundation walls for the basement. At the southern edge of the pool wall that divides the Champlain Towers South from the 87 Park condo on the southern edge of it, photos from the lawsuit show actual open gaps from where the beach access sidewalk from 87 Park meets up against the wall for the pool. And you can see how easily water can get down there and so it doesn't take long to soak into the part of the wall that is underground where the rebar is which is probably maybe only inches down from that ground level. Although a caveat is that the water has to soak through concrete blocks also. I would love to see some recent photos from inside the garage on the southern end right up against that wall there to see if any water had leaked down into the garage. Also 87 Park builders should have waterproofed that whole area, and I would love to see what their drainage plan is for this development along that beach access sidewalk.

AusTony2046 to answer your question on how that minuscule movement could have brought down the building. Once the pool deck detaches from that south wall if that is indeed how it started, the pool deck propagated north towards the building where it hits the planters over Column M 11.1. Once you hit that point and column 11.1 falls, now added loads are on the remaining spindly/damages/waterlogged columns in the area. When the rest of the planters in the pool deck fall, everything else in that area has already been weakened including the area where the fitness center is as indicated by the Miami Herald article. As the pool deck starts to collapse down there's that beam that runs the whole length of the southern end of the building that begins to rotate and as it rotates it tears away from the other three or four columns along the southern edge of the building so they will begin to collapse.

So there was likely no waterproofing to obstruct horizontal travel of water from the adjacent property. Was this a common practice at the time? Is it still? If it is/was not, it implies it was an accepted practice.

Of course, if the water that caused the damage came from the other property, it arrived at the southernmost part of the rebar first, and the bend in the rebar would likely be the most corroded, being more impacted by the encroaching water.

In his video from August 13 of last year, Josh Porter noted that the concrete deck was heavily overloaded in the area where some beams were removed during a redesign. This would be where the surface level parking met the pool deck. With that, I believe he thought it likely that the failure started there.

If it did, the fail would have had to proceed eastward, towards the pool. The weight of the falling slab would have hit the rebar connecting the south underground wall with the pool deck unevenly, in that the greatest load on all the rebar would have been on the first one to the east. If the weight was enough, it perhaps could have sheared. Then the next rebar would be heavily loaded, and it would shear. And the next, in a zipper fashion, all the way to the expansion joint.

So perhaps the rebar wasn't particularly weakened by water in this area; perhaps it was overloaded in shear.


spsalso

The "Building Integrity" guy is a complete idiot! The slab is irrelevant, the load rests on columns and the beams that distribute that load. I have never really cared what happens to subgrade walls or slabs once a building is constructed in this region simply because after dewatering and construction the weight of the building results in a hydrostatic environment that prevents water intrusion at subgrade.

The membrane is extremely important to protect the beams and from being weekend, in this case the beams failed, which resulted in very large loads being transferred to single points that were so overloaded that the building failed.

I stated a few posts back that the sheet piles were nothing more than a means to an end, which was to excavate, dewater and pour non-load bearing walls, and trust me that zero load is exactly what the perimeter wall carries.

The "Membrane" is simply to protect the beams and columns, the slab is merely there to provide a nice flat surface to walk or drive upon.

What will really screw with you is in post-tension construction, it is 100% forbidden to have any load transfer on a wall.

Quote (Keith_1 "Structural")

Well, I have to admit, I had never considered "a hydrostatic environment" preventing water intrusion to be a factor in this building. Learn something new every day.

Enjoy your weekend.

I would think the slab falling down would be relevant. If nothing else, it squashed a lot of cars.

According to the complete idiot, the beams you refer to as distributing the load were removed from the plans without doing structural correction for the removal.

If the perimeter wall carries zero load, why even connect to it? If it carries zero load, you could stop the slab an inch short. And save a couple of bucks.


spsalso

The southern perimeter wall where the upper parking was, that would have needed to bear some weight I would think.
The columns were larger there, but some weight would have needed to be distributed along the wall as well...and that did collapse.

Those beams that were in the plans but left out along that area, that was a huge mistake with both the weight of the vehicles and the planters there.

My thought, which I may have not expressed well, is that the points of failure of the rebars between the south wall and the slab might have been caused by the vehicle/planter slab falling, and unzipping/shearing those pieces of rebar as it took down the adjacent pool deck slab.


spsalso

The "south" wall or any other similar subgrade wall has no direct compressive load from the building, nor is there anything that transfers that compressive load to said members, therefore it is irrelevant.

In terms of hydrostatic pressure, yes it can be a concern because sometimes buildings can sctually float until such time there is enough weight to surpass equilibrium, and the soil becomes dense and compacted enough that it becomes impermeable

Keith, the discussion of the video was regarding the deck slab failure, which ties into the south perimeter wall.

With my bad hearing this is the best I could do for the spanish audio tracks on the Dec 30 Miami Herald article (https://www.miamiherald.com/news/special-reports/s...):

Vázquez story:

Entonces en el auto, como siempre en la cochera, ya escuchamos un ruido muy, muy ... muy fuerte. Pero no seamos(?) a ... a entender que pasaba.
Y en diferencia de seis, de segundos, de segundos, el ascensor ... se movió el ascensor, parando en el lobby como siempre
Y umm arrancó una ... una polvareda muy fuerte, un estruendo muy fuerte como si fuera ... no sabía - no entendía que pasaba.

Then (we were) in the car, as usual in the parking garage, we heard a noise, very, very ... very loud. But we didn't get(?) to ... to understand what was happening.
And after six, after seconds, after seconds, the elevator ... the elevator moved, stopping at the lobby, as usual. And ummm a ... a very strong cloud of dust started, a very loud noise started as it it were ... I don't know - I didn't understand what was happening.

Sarmiento's story:

Cuando salímos (???) como a las una y cuarto de la mañana a la piscina, eh yo siento, como es un campo abierto, la zona de la piscina, yo siento un ... un colapso. Boom. eh Sale aire y un viento después de que colapsa el techo del estacionamiento. Sale un viento por el garage y empiezan a sonar las alarmas de los carros. Empieza a sonar los chorros de agua y de (???) a mirar para todo lado a mirar de donde salió ese sonido porque era algo extraño. Sabía que algo estaba pasando. Cuando yo veo el techo del estacionamiento prácticamente todo ese pedazo en el piso y los tubos rotos botando agua, yo le digo a la gente que está ahí que es mi esposo y (???) le digo: Eso se va a caer.

When we were going (???) about 1:15 AM to the pool, uh I felt, since it is open, around the pool, I felt a ... a collapse. Boom. uh Air comes out and a wind after the collapse of the roof of the parking garage. A wind comes out of the garage and the car alarms start going off. You can start hearing the water coming out and (???) I start to look everywhere to see where that noise came from because it was somewhat odd. I knew that something was happening. When I saw the ceiling of the parking garage practically all that piece on the floor and the broken pipes with water pouring out, I said to those around me that was my husband and (???) I say: That is going to fall.

Monteagudo's story:

Yo siento dos crujidos eh seguro muy fuerte. Cuando miré a mi costado derecho, ví que estaba bajando una una raja... una grieta del techo hacia el suelo por la pared y esa grieta, a medida que avanzaba, separaba a la pared en dos.

Eso se fue un decimiento(?) que empezó a hablar y a decirme: tiene que irse de aquí porque eso se va a ... a caer.

I heard two cracking sounds uh for sure very loud. When I looked to my right side, I saw coming down the wall a a crack.. a large crack from the ceiling to the floor along the wall and that large crack, as it grew, cleaved the wall in two.

It was something(?) talking to me and saying to me: You have to leave because this is going to ... to fall down.

I think I may have solved the mystery of the crack in 611 (Monteagudo). The Miami Herald article shows the crack on the east wall of 611, which would be along the Row M of columns. Based on another look at her testimony, it would appear that the crack is on the opposite wall. The Miami Herald shows the following illustration:



Based on a study of the transcript (corrected) of her testimony, which is referenced in the Timeline, she was apparently facing her balcony door, which wouldn't close, when the crack appeared to her right. Accordingly, the crack would be on the wall between the living room and the bedroom as shown as follows:



As you can see, this is much closer to Row L. Thus the crack would be consistent with the theory by Mike Bell, which theorizes that the building collapse begun with columns K9.1, L9.1 and M9.1 and not near the weight room. It would appear from the transcript that Mrs. Monteagudo woke up when the pool desk collapsed and barely made it to the western staircase before the building collapsed, which took about 7 minutes. The collapse sequence then may have been as follows:

A. Pool Deck collapses. I still favor the collapse at the edge of the parking deck due to fatigue failure and not at the southern wall.
B. The pool deck collapse damages columns K9.1, L9.1 and M9.1, so that they are no longer able to support the facade. A small displacement would suffice. The building immediately begins to find new load paths. Unfortunately, the step beam along Row 9.1 was apparently NOT anchored to the shear wall at the elevators. I have not been able to find a structural detail for how the step beam was supposed to be anchored to the shear wall. Unfortunately, I have not been able to find any pictures which show that detail. However, it appears that the entire building was not anchored to the shear wall very well if at all.

Here is an animation of Mike Bell's theory:

https://res.cloudinary.com/engineering-com/image/upload/v1642399134/tips/Mike_Bell_animation_8AXsK1D_p1ffhn.webp
https://res.cloudinary.com/engineering-com/image/upload/v1642399167/tips/Mike_Bell_animation_qsfZCKn_mxs50h.webp

The English translation of Mrs. Monteagudo's testimony from the above referenced you tube clip is as follows:

I was sleeping and a higher power woke me up that there was an unusual atmosphere in the apartment and I heard some strange sounds. I thought that I had left the balcony door open and when I went to the living room, indeed the door was open from the living room to the ocean, to the water, to the balcony. I tried to close it and I couldn't. It seemed as if the door track was no longer level. And then I heard another crack (at about 00:45 she turns to her right) and when I heard this crack I look at the wall and I see a large crack going down from the ceiling that was two fingers wide. Something told me: this is going to fall. I ran to the bedroom. I took off my bed clothes. I put on a dress, some flip-flops or whatever you call them and I got to the dining room. I took my purse that had my ID and my credit cards, a pill box, the key and these things that I had taken off that I still had I put them in. I put out the candle to the virgin Mary and just in case I closed the door. I didn't know where the exit stairs were. I went to the elevator that was much further away. I did not know that I had two exit stairs next to my apartment. If I had know that there were two exit doors next to my apartment, I would have thought to take the quickest one. And I wouldn't have gone to the one further away. Anyway when I was in the furthest staircase, when I got to about the fourth (sixth - fourth) floor, I heard an infernal noise, but an infernal noise that I knew that part of the building had fallen down. I saw the security very thin like a little boy that said there had been an earthquake that there had been an earthquake and I said it wasn't an earthquake. This had fallen: the building - this one and suddenly the legs failed me, I don't know, but I got the top that I needed to get to. Then there was an enormous space that I had to jump - another obstacle to reach the street but I couldn't. Then God found me a piece of rubble that served as a step. I put my foot on the step - the right foot - the left foot that was enough so that I could get to solid ground.

The corrected and punctuated Spanish transcription is as follows (I have only transcribed Mrs. Monteagudo's testimony):

Yo estaba dormida y una fuerza superior me despertó que había un ambiente enrarecido en el apartamento y yo sentí unos ruidos extraños. Yo pensé que había dejado la puerta del balcón abierta y cuando voy a la sala, efectivamente estaba abierta la puerta de la sala al mar, al agua, al balcón. Traté de cerrarla y no pude. Parece que se había desnivelado ya el riel de la puerta. Y siento otro crack y cuando siento este crack que miro la pared veo que viene bajando una grieta del techo para abajo de dos dedos de ancho. Algo me dijo: esto se va a caer. Salí corriendo al cuarto. Me quité la ropa de dormir. Me puse un vestido, unas chancleticas de meter el dedo y cómo se llama y llegué al comedor. Agarré una cartera que tenía con mi ID y mis tarjetas de crédito, un pastillero la llave y estas cosas que me las había quitado las tenía encima las metí. Apagué la vela de la virgen y por si las moscas cerré la puerta. Yo no sabía donde estaban la escaleras de escape. Me fuí al ascensor que me quedaba mucho más lejos. Yo que yo no sabía que yo tenía dos escaleras de escape al lado de mi apartamento. Si yo sé que hay dos puertas de escape al lado de mi apartamento, me hubiera ido pensando que la rapidez. Y no me voy a la lejos. Bueno pues en la lejos cuando llegó por el piso 4 y 6-4 yo siento un ruido infernal, pero un estruendo infernal que yo sabía que se había caído parte del edificio. Ví al security flaquito asi (como) un niño que decía tuvo un terremoto tuvo un terremoto y yo dije no es un terremoto. Esto que se derrumbó: el edificio - este y de repente las piernas (me fallaron) que se yo pero llegué al tope que tenía que llegar. Después estaba un espacio enorme que tenía que saltar otro obstáculo más para llegar a la calle pero no podía. Pero Diós me puso un escombro que me sirvió de escalón. Puse el pié en ese escalón en la pierna izquierda la pierna derecha me dió para llegar a tierra firme.

The corrected Spanish transcription retaining the you tube timing is as follows:

00:21 ...... (START) yo estaba dormida y una
00:24 fuerza superior me despertó que había un
00:27 ambiente enrarecido en el apartamento y
00:29 yo sentí unos ruidos extraños yo pensé
00:31 que había dejado la puerta del balcón
00:32 abierta y cuando voy a la sala
00:35 efectivamente estaba abierta la puerta
00:36 de la sala al mar al agua al balcón
00:39 traté de cerrarla y no pude parece que
00:41 se había de nivelado ya al riel de la
00:43 puerta
00:44 y siento otro crack y cuando siento
00:47 este crack que miro la pared veo que
00:49 viene bajando una grieta del techo para
00:51 abajo de dos dedos de anchos algo me
00:54 dijo esto se va a caer
00:56 salí corriendo al cuarto me quité la
00:58 ropa de dormir me puse un vestido unas
01:00 chancleticas de meter el dedo
01:03 y cómo se llama y llegué al comedor agarré
01:07 una cartera que tenía con mi ID y
01:10 mis tarjetas de crédito un pastillero
01:12 la llave y estas cosas que me las había
01:15 quitado las tenía encima las metí apague
01:18 la vela de la virgen y por si las moscas
01:20 cerré la puerta yo no sabía donde estaban
01:22 la escaleras de escape me fui al ascensor
01:25 que me quedaba mucho más lejos yo que yo
01:27 no sabía que yo tenía dos escaleras de
01:28 escape al lado de mi apartamento si yo
01:31 sé que hay dos puertas de escape al lado de
01:33 mi apartamento me hubiera ido pensando
01:35 que la rapidez y no me voy a la lejos
01:38 bueno pues en la lejos cuando llegó por
01:41 el piso 4 y 6-4
01:44 yo siento un ruido infernal pero un
01:46 estruendo infernal que yo sabía que se
01:50 había caído parte del edificio ví al
01:52 security flaquito asi un niño que decía tuvo un terremoto
01:56 tuvo y yo dije no es un terremoto esto que se
01:58 derrumbó el edificio este y de repente las
02:01 piernas que se yo pero llegué al tope
02:03 que tenía que llegar después estaba
02:05 y un espacio enorme que tenían saltar
02:08 otro obstáculo más para llegar a la calle pero no podía
02:12 pero Diós me puso un escombro que me sirvió de escalón puse el pié en ese escalón en
02:18 la pierna izquierda la pierna derecha me
02:20 dio para llegar a tierra firme (STOP) ...

Hat tip to clouditguy:

Matterport (3D walkthrough) supposedly of 611:

https://my.matterport.com/show/?m=4USu8mRgGim&...

Great work, IEGeezer. I have always theorized, based on the interview you translated, that it was the west wall that cracked. After I saw the latest infographic showing the crack in the east wall, I searched for new interviews with Ms. Monteagudo that might support the infographic and found nothing. If it is correct, the 3D rendering showing her furnishings makes it clear that the most unobscured living room wall was on the west.

Ok, ENG 101

This is a pile foundation which means that all compressive loads (weight of the building) are transferred directly into the ground. The Beams in the garage simply distribute the load from the top floor down to the piles. The video clearly shows that there was no tie in to the deck at the perimeter wall.

If there was a structural load bearing /transferring connection between the perimeter wall and deck, it would be tied into the piles, and there would be a transfer beam. This makes no sense, because you would be taking a tension load and trying to put it in tension. This is just stupid.

I don't care about Ms. X experience, the beams failed due to failure to protect the membrane and the compressive loads were no longer transferred, that is it.

Decks are just to stand on, and yes there is a limit on the static and live load of the deck in terms of span length, but unless you are going to put up some serious analysis regarding the capacity of the span in this instance, you look like idiots.

Quote (Keith_1 (Structural)19 Jan 22 11:1)

If there was a structural load bearing /transferring connection between the perimeter wall and deck, it would be tied into the piles, and there would be a transfer beam. This makes no sense, because you would be taking a tension load and trying to put it in tension. This is just stupid.

I don't care about Ms. X experience, the beams failed due to failure to protect the membrane and the compressive loads were no longer transferred, that is it.

Decks are just to stand on, and yes there is a limit on the static and live load of the deck in terms of span length, but unless you are going to put up some serious analysis regarding the capacity of the span in this instance, you look like idiots.

Dear Keith,
I just looked at the plans.
There are NO columns at the south side of the VALET parking slab.
What holds up the cars and planters?
If you don't care about the occupants of the building, I would hate to be in one of your buildings!
Maybe it was someone like you that designed this just stupid building.

(OK OK, I'll climb back in my teapot now...)

What are the intentions of the #5 90* hooks?

Edited to fix pre-coffee grammar.

I would think that the cars parked on the southern side of the parking area would provide a load for that wall, through the deck edge.

If not, wouldn't they then be supported by a cantilevered deck?


spsalso


And it also would appear that re-bar in this building wasn't always installed where it should have been, so the lack thereof does not mean it wasn't necessary and/or planned.

Keith 1

No one here disagrees that the membrane and it's maintenance was a big concern. But a few of us disagree with you that the perimeter wall was built to hold zero load.

I also believe you mentioned it was a post-tension build and that Josh from Building Integrity researched this and said it was NOT a post-tension build.

You keep mentioning the beams, some beams on the plans were not actually installed...which beams and "their condition" are you referring to?

Please stop with the name calling, it does nothing to further our comprehension of your conceptions.

@Optical,
I don't believe Keith said it was post or pre-tensioned. Possibly in an old edited/deleted post, but I see no mention of that; anymore at least.


However,

Quote (Keith_1)

There are simply no defects in the construction of this structure, it was entirely a lack of maintenance

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

Demented

On the 15th he ended his post with -
"What will really screw with you is in post-tension construction, it is 100% forbidden to have any load transfer on a wall."

I took that to mean he was talking about this build.

Even if that wall was supposed to have no tensile load applied to it, the contention in the BI video is that the failure of the slab at the pool deck column heads was giving it one.

And yeah it must have been supporting a compressive vertical load of the southernmost span (south of the last column) even at design time.

@IEGeezer I think you have an error on your floorplan drawing of the Monteagudo condo unit. Your red lettering shows K9.1, L9.1, M9.1. I believe that should be K10, L10, M10.

As there is no row nine of columns anywhere on the 11th stack units or any of the other units on that part of the condo building. The number 9 row of columns is over on Collins Ave side, the “06” stack of condo units for example.
Also interesting that Mike bell pointed to those three columns because he has commented on my video and chastised me for focusing on M11.1, he told me to give it up already and move on, LOL.

When in fact I think M11.1 is a strong candidate for where the deck may have originally collapsed in the first place. I don't think that the deck collapsed at the south wall is because if it had collapsed there that part would be down on the ground first and everything else probably sticking up higher but instead it looks like everything else collapsed first while the part of the pool deck that attached to that south wall was sort of hanging and leaning up against the wall.

That's why I don't think that's where the pool deck collapse began. I think the weakened, waterlogged area over M11.1, combined with exploration work done there that was not repaired per Morabito’s instructions led to the pool deck dropping.

Quote (Jeff Ostroff)

@IEGeezer I think you have an error on your floorplan drawing of the Monteagudo condo unit. Your red lettering shows K9.1, L9.1, M9.1. I believe that should be K10, L10, M10.

Actually, they are both correct. There is no number 9 row there, but there is a number 9.1 row.

The #9.1 location marker on the drawings indicates the center-line of those columns and the #10 indicates the outside surface of those same columns but it is a hard dimension because it defines that outside face of the building. For another example, the North East corner is P-1 on it's outside surface but O.1-1.1 for the center-line.

This was a common practice with some architects because if there was ever a revision to the drawings that called for a different size column on the #9.1 line for example, it would be required to shift it over accordingly to keep the #10 line straight.

@Jeff Ostroff

Quote (I think you have an error on your floorplan drawing of the Monteagudo condo unit. Your red lettering shows K9.1, L9.1, M9.1. I believe that should be K10, L10, M10.)

On the Morabito blueprints there does not appear to be a gridline 10. I am referring to Sheet D2C-1.0 dated 04/26/2021.

Quote (Also interesting that Mike bell pointed to those three columns because he has commented on my video and chastised me for focusing on M11.1, he told me to give it up already and move on, LOL.)

I don't think there is a conflict between focusing on M11.1 and K9.1, L9.1 and M9.1. I think M11.1 did NOT fail in punching shear and its failure led directly to the failure of the KLM9.1 columns. The failure of the KLM9.1 columns is difficult to explain without what happened to KLM11.1. Had KLM11.1 NOT failed, the building might still be standing or it would have stood long enough for more lives to be saved.

Quote (When in fact I think M11.1 is a strong candidate for where the deck may have originally collapsed in the first place.)

M11.1, K13.1 and K14.1 are all overloaded by the planters. Regardless of which failed first, the others failed within seconds.

Quote (I don't think that the deck collapsed at the south wall)

Agreed.

This is not a post tensioned building. What I was saying is that is that there is no hard connection between the wall and the deck in that type of construction In PT there is a at least 5/8th of an inch between the block or curtain and the deck. When you pull tendons you actually lift the deck up,and a hard connection between the deck and wall would be an extremely bad idea.

I was making an analogy as to why the perimeter wall is nothing more than a retaining wall, snd is not load bearing.

But not answering the question about what is supporting the load of the cars parked above that wall.

spsalso

It's pretty clearly the perimeter wall, whether that violates the content of Keith's ENG 101 rubric or not.

Quote (spsalso)

...what is supporting the load of the cars parked above that wall?

Ok, ENG 101.one,

Obviously, the hydro-static pressure induced by the membrane maintenance oscillator allows the slab to float on a cushion of highly viscus load bearings that prevents water intrusion at subgrade. The redundant mystery beam mount provides the stability needed for the eye beam housing attachment and retrograde decompression at the perimeter circumference.

The equilibrium vortex created by the youtube monetary distribution algorithm is counter propagated with an elaborate system of sonic spectrum drivers and valet moonbeams to keep the anti-frequency audio drivers in alignment on the perimeter tie-in bracket from interfering with the bull sheet piles.

If this should ever fail, the palm tree removal process would begin displacing the axial bilateral forklift extractor. Having the tar-kettle core orientated in such a way as to provide buoyancy compensation to lift the bucket-o-nonsense from the anti-gravity well, increasing the likelihood of pre-tensionary tendon reduction with the added benefit of providing pressure wave delta phase reciprocation. (You know that's a good thing, right?)

@keith I always wondered could they have done better with the load bearing of the pool deck up against that South wall simply by placing a second wall in front of that existing South wall and up against the south wall that that now the pool deck can rest on top of that 2nd wall like a roof truss does on a regular brick house. Then they could tie in the pool deck to the South wall whatever method they were going to do and it still has its load bearing Underneath it by the secondary wall of bricks in front of the South wall. So the differences between the 2 walls would be the South wall connects head on into tge poldeck slab, where is the 2nd wall sits underneath the pool deck giving it the load support. Alternatively they could have just built that South wall so the edge of the pool deck rests on top of it rather than tie into it.

NukeDude948,

When someone explains things as clearly and logically as you did, it is very embarrassing to find that one didn't think of it on one's own.

Talk about missing the obvious!

I hesitate to bring this up, but are you perhaps a student of Ron Hamburger? There's a familiar ring,.......


spsalso

*raises hand*
Teacher, I has question.

If the southern wall was just a retaining wall and not a load bearing wall, why would a reinforced concrete wall need be built? Couldn't you just leave it at the steel sheet piles? Why have 2 retaining walls butting up together?

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

@keith I always wondered could they have done better with the load bearing of the pool deck up against that South wall simply by placing a second wall in front of that existing South wall and up agaianst the south wall that that now the pool deck can rest on top of that 2nd wall like a roof truss does on a regular brick house. Then they could tie in the pool deck to the South wall whatever method they were going to do and it still has its load bearing Underneath it by the secondary wall of bricks in front of the South wall. So the differences between the 2 walls would be the South wall connects head on into tge poldeck slab, where is the 2nd wall sits underneath the pool deck giving it the load support. Alternatively they could have just built that South wall so the edge of the pool deck rests on top of it rather than tie into it.

A simple beam supported between two columns will end up with a force profile where the 1/3 on the ends will be in compression and the 1/3 of the center will be in tension. This is why the wall is irrelevant as there is no load being transferred to it, for the simple reason there is nothing above it.
Loads in a building basically go straight down, A few kips of live load on the driveway is nothing, the issue is the weight of the building and balancing them and transferring to the foundation.

If Hydrostatic issues were not a major problem, houses in Florida would have basements, subgrade work is extremely difficult. I have used t-55 turbine powered pumps to dewater a site via point well for underground parking, and it is nothing I will ever do again, it was a total nightmare.

For the keyboard warriors, what supports that wall? I'am talking foundation what carries the load? It there was a grade beam over piles piers or even a footers then that would be one thing, but there is nothing under that wall.

OK.

Keith is ignoring me, but I see that he is saying that only the weight of the building is worth bothering about. The weight of some cars, "A few kips of live load on the driveway", "is nothing".

And that would be the live load transferred to the top of the "retaining wall".

Yes. It is certainly true that the south wall of the garage was not heavily loaded by the building.

But it would appear that he is still in error by saying it "is not load bearing". He, unfortunately, did not say "only lightly loaded". He made an absolute statement, which still appears to be wrong.


spsalso

Quote (spsalso)

I hesitate to bring this up, but are you perhaps a student of Ron Hamburger? There's a familiar ring,......

No, not a student of his or his work.
Of course you realize that, somewhere, someone must have been Ron Hamburger's "mentor".
Sorry, that wasn't me either.

Keith will continue to ignore anyone that brings up hard questions. He can't explain his ideas clearly enough for anyone to understand what concept he is trying to convey, and obviously can't back up any of his nonsense with documentation, facts, pictures, or any other types of evidence. You could either ignore him or poke fun at him. Life is too short to actually try to engage in debate with him.

Thank you, NukeDude948.

spsalso

Maybe that's why stuff in Florida, south FL in particular gets messed up so much down here.

Got your degree with straight c's?
Have at least some "experience" on your resume?

HERE'S YOUR PE LICENSE GOOD SIR. BETTER CARRY GOOD INSURANCE.

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

I'm puzzled as to why the vertical load capacity - or otherwise - of the south wall is suddenly a thing. The point, and I have been paying attention down the back here, is the sag of the deck and heavy planters creating a catenary force on the load-bearing columns and/or load-transferring beams in that critical KLM area of the building, with the collapse of the deck imparting a rotation and loss of support to those structural elements and pulling the rug out from under. If the deck letting go laterally from the south wall can be shown to contribute meaningfully to that story so be it. If it would make little difference, ok, bang goes that component. But in no case does anything in the working hypothesis depend on building load appearing at the south wall. That would be ridiculous and no-one is promoting it.

AusG,

It started with the concept that the construction to the south could have been at least contributory to the collapse. And if it did, the "entry" would have been at the south wall.

The discussion entered into the area where the deck and the vertical wall of the garage meet, and the purpose and type of the connection. And the failure in this area. This included such things as the scrapes on the wall caused by the broken rebar as it fell.

My contribution was speculating that that area failed from west to east as the parking area/planter went down, falling first.

I think others might have speculated that the fail DID start at the pool deck garage wall interface, caused by damage by the southern construction. I believe there is a lawsuit that asserts something like that.


spsalso

I find the discussion of the wall being load bearing or not interesting. It may have had something to do with the pool deck collapsing.

However, the pool deck collapse did not bring down that building.

From the sequence of events it has been made clear that the Nirs and Security heard sounds from above, the Nirs hearing this for at least an hour prior to the collapse and unit 1211 hearing sounds the night prior.

Mrs Nir heard what sounded like a wall falling into hers Before the pool deck and the parking deck fell.

We have to look closer at the Above sounds and the shear wall.

Spalso, the west to east fracturing also goes along with what Nir's son said about it feeling like a collapsing card table. The rebar pulling from the shear wall, I'd say may have started several floors above which coin sides with the blocks falling into the elevator shaft.

Hello,
I have been closely watching the information being released about this collapse since it occurred, and also working to understand and communicate some of the potential risk factors, but I only started paying attention to the information being posted here a couple of weeks ago. It has taken me that long to read all of the previous posts and take notes on the information I found to be most credible. I am very grateful to everyone who has contributed their time, knowledge, imagination, creativity and dedication to understanding the causes.

Quote (Keith_1)

what supports that wall? I'm talking foundation what carries the load? It there was a grade beam over piles piers or even a footers then that would be one thing, but there is nothing under that wall.

Keith, please refer to the section detail of the perimeter wall posted by structuralex in part 02 on 30 Jun 21 14:22 it clearly shows the structural support.

Quote (AusG)

If the deck letting go laterally from the south wall can be shown to contribute meaningfully to that story so be it

If the vertical support provided by the southern wall is removed, the guest parking deck area is essentially supported in cantilever only by a single column, I14.1, with partial support by column 14.1 G.1 and column 15 J.1 (actually located between J and K but not explicitly identified on S4 of14). I'm quite confident that calculations will show that even under optimal construction and maintenance conditions, the design strength of the column slab detail at I14.1 would insufficient to support that load and the associated bending moment. The problem is that the column is only 2 feet square and the load is effectively being applied more than 20 feet away.

Quote (Optical98)

However, the pool deck collapsed did not bring down that building. From the sequence of events it has been made clear that the Nirs and Security sounds heard from above,

That is only part of the story and relies on their perception of the direction of the sound source being correct. The sequence (thanks very much for the timeline MaudSTL) includes descriptions of "cars jutting out" at ~1:15, reports of the pool deck collapse at >1:17, both events before the building collapses. The problem with accurately understanding the direction of the sound is that people are very accustomed to hearing noise from above due to occupants in the appartment above, but much less frequently from below (requiring someone to be banging on the ceiling of the garage). Also with structure bourne noise the sound is propagating from surfaces of the room so the surface finishes have a strong influence over the relative levels, carpet will reduce the apparent level from below. Direct sound propagating through the front windows is likely to bounce off the ceiling.

Quote (Jeff Ostroff)

Alternatively they could have just built that South wall so the edge of the pool deck rests on top of it rather than tie into it.

Jeff, The parking deck was resting on top of the South wall after rebar failed. The single row of vertical rebar at the wall slab connection was forced to work as a hinge to accomodate the thermal expansion and contraction of the deck and was alo exposed to the highest level of salt and chloride concentration. The constraint of the deck was far more stiff at the north side where the building was.

I just don't have time to check this every day.

I do agree that if the Beams were weekend of course the slab was, but they serve two totally different purposes. If this were a localized point of failure that was not at grade or subgrade, and resulted in this type of failure it would raise questions, but not very difficult ones, in the context of a 40 year old building.

The biggest issue that that has ever occured in terms of decks occured with post-tensioned system widely used in the 1970's that was a trifecta of really poor metallurgy, design and installation detail, especially with the bonded tendons. This was a real and 100% defect in a construction product, and trust me not a single architect, engineer or contractor would have ever intentionally used such a product in construction. I would like to say that there was no failure that. like chapman resulted in the loss of life, but there were, especially in Northern Parking structures. Once the problem was known and understood, the building professions remediated alot structures, that to this day, and for many decades into the future, will be strutrualy sound and safe.
I just don't have time to check this every day.

I do agree that if the Beams were weekend of course the slab was, but they serve two totally different purposes. If this was a localized point of failure that was not at grade or subgrade, and resulted in this type of failure it would be a real head scratcher.

The biggest issue that that has ever occurred in terms of decks occurred with post-tensioned system widely used in the 1970's that was a trifecta of really poor metallurgy, design and installation detail, especially with the bonded tendons. This was a real and 100% defect in a construction product, and trust me not a single architect, engineer or contractor would have ever intentionally used such a product in construction. I would like to say that there was no failure that. like chapman resulted in the loss of life, but there were, especially in Northern Parking structures. Once the problem was known and understood, the building professions remediated a lot structures, that to this day, and for many decades into the future, will be structurally sound and safe.

The above is actually a real long term defect in construction that took years to be understood, there was no nefarious intent and I think every engineer that was involved in designing that system was haunted by their mistakes.

The Miami bridge collapse is different, in that instance I actually place the blame on everyone involved -- especially the field engineer that tensioned or de-tensioned those cables. Hell, I blame the super and project manager for not vacating the deck, stopping traffic and not calling the fire department. They actually should have known better, so put them all in jail. I would never work on a tendon with anyone standing over it, under it, or within a hundred feet in front of it. If you are stressing a tendon and someone gets injured or killed it is your fault, and in my opinion should be criminally responsible. Side, note -- I had one fail in my life, it tore up 8 feet of concrete and embedded itself halfway into an 8" concrete wall that was 80' feet away, no one got hurt because I controlled the environment around me.

Chapman, failed because unfortunately professionals are simply not involved post construction, because frankly we find dealing with a bunch of idiots taxing and not worth the time. If Chapman would have called me, I would have told them I need a check for $200,000, and would have started shoring immediately, it would not have fallen.

They ignored advice, did not heed the warnings, and did everything they could not to get good advice, it is on the management company, the property manager and the Board, not on qualified construction professionals.

Quote (Keith_1)

I have a rather large resume, you do not, so where do you think you stand on this side of the equation.

*eye roll*

No one cares about, or is impressed by, the alleged size or alleged voracity of your resume, dude.

What people DO care about, in this context, is clear presentation of facts with at least some minimum level of clear forethought backing them up.

Every single person in this thread is speculating; we all know that. Blanket statements about the facts, especially in concert with blanket statements about your alleged intellectual superiority, are the real waste of time here.

Quote (Keith_1)

I know for as a 100% fact this was not a design issue

No you don't. The fact that you keep trumpeting that you know everything is not helping your case. You must be a real peach to work with in the real world.

Quote (Keith_1)

If you think a property management company is qualified to understand these types of issue, you are the problem.

Huh? I never said anything of the kind. Some property managements companies may have the staff to understand a scenario like this, where a building in their charge is damaged and in need of extensive repair. But I never said (nor do I believe, nor do I believe anyone else in this thread has said or believes) that this particular property management group had the right expertise or made any good decisions.

Quote (Keith_1)

The last time I checked, a mechanical engineer sits in a cubicle and speaks to no one, except when I call them and tell them that I need to change the size of a duct, so I really can not imagine a more unqualified professional other than a "computer engineer" to assert authority in this matter.

Ha! Once again... no one in this thread is truly aware of the 'resume' of anyone else in this thread. Funny how the only one spouting off about how strong their resume is, while denigrating the experience of others they know only by a handle in a forum in the backwaters of the internet, is YOU.

All you're doing is making yourself look like a clueless dick.

If you have nothing constructive to add to the discussion, go somewhere else. If you want to explain why you're so confident in the blanket statements you keep making, have at it. But at the moment you're 100% wasting everyone's time.

There are alot of design issues that exists, especially with lap lengths and coverage with balconies, but they don't result in the collapse of abuilding. There is a huge difference between some bad temperature steel, or a few bad bars on a balcony going bad, and the total failure of the entire foundational system. Yes, slabs do spall, but for a total failure is alot more than a #7 bar, it is cascading failure due to sure neglect and stupidity.

There is so much redundancy that the failure of a beam or column is not going to result in the total failure of a completed building, especially at 40 years. This thing was so neglected I would charge the property management company, the engineer and everyone else that did not file a report that it was a life saftey issue with at least aggravated manslaughter. This was 100% preventable, and even a basic understanding of structures would have prevented the loss of life that occured with Chapman.

Just accept that if the membrane was protected this would never have happened, and that even days before the failure, that if someone would have shored up the beams and de-compressed the columns that it never would have not of failed until it was repaired. Shoring can do alot more than you think, especially when it is a deflected load that so many think is the major cause of failure.

Chapman or Champlain? You may be thinking of a compmetely different building, which would explain a lot.

I hope your grip is good Keith 'cause I'm passing the crazy torch off to you.

I have a question. If you know the construction to the south is damaging your property, why didn't you do anything about it?

Quote (IanCA)

Keith, please refer to the section detail of the perimeter wall posted by structuralex in part 02 on 30 Jun 21 14:22 it clearly shows the structural support.

Here is the section detail dug up by IanCA. This sure looks like a turned down slab at grade supporting the South Retaining Wall, via direct load transfer to the hydrostatic soil below and thus the retaining wall supports the patio deck.

Quote (thermopile)

This sure looks like a turned down slab at grade supporting the South Retaining Wall, via direct load transfer to the hydrostatic soil below??

That is correct. Also the drawings show piles on 12 foot centers supporting that slab around the entire perimeter to handle the load. Page 307 of 336 from the big set of drawings or page S1.

thermopile,

There is no such thing as a "down turned slab" if it where it would be a footer or a grade beam. Slabs are on the ground, decks are suspended.

There is an 8" wall running from the West corner of the building to the East corner with #5 bars horizontal and vertical @ 12", and a section of wall from the East corner that is a 12" wall for 10' with #5 bars hortizontal and vertical at 16' centers. The corner is just what a corner is, because you always reinforce them to account for wind loading. Even in a single story CBS house you will have more steel and fill cells in the corners.

NuleDuke, so you have pile 12' on center, that shows nothing in relation to the perimeter wall. I actually know the order of construction, so I know that the sheet piles were installed before the piles, and I also know that there is not a pile under that wall.

Kweef_1, You are looking at the drawings wrong. What you are calling a 12" wall for 10' is the section view of the slab. It is thickened, or turned down as some people say, around the perimeter of the building. The wall is 8" thick and its height varies. At the top of that drawing is the 9.5" pool deck. Those piles are under the thickened portion or footer of the slab. Please take a few minutes to look at the drawings that we are showing you. You can download the full set of drawings from the city of Surfside.

thermopile, the one thing that you missed was that 12" section is called out at an elevation of 2' 2" which above whatever the slab elevation is. It really does not matter what the purpose of that 12" section because it does not transfer to the foundation. 2 is not 0,learn how to read a plan. I would be nicer if you people actually accepted reality.

Quote (Keith_1)

the one thing that you missed was that 12" section is called out at an elevation of 2' 2" which above whatever the slab elevation is.

Dude, the slab elevation is at 2' 2" above sea level. That is the reference point that they used here. Look at page S14 of the drawings. It is page 35 of 336. It shows elevation of each floor. It would be nice if YOU accepted reality.

Quote (NukeDude948 (Electrical))

2' 2" above sea level

That might be a kweef too far.

Quote (Keith_1)

Long winded personal attack

You're, as is becoming typically for you in this thread, woefully incorrect. Not that it matters very much. I don't claim to know you, and at this point I don't care to. So how about we just stick to the facts. Maybe that will get you to understand why you're not correct.

Quote (Keith_1)

what supports that wall? I'm talking foundation what carries the load? It there was a grade beam over piles piers or even a footers then that would be one thing, but there is nothing under that wall.

Quote (Keith_1)

NuleDuke, so you have pile 12' on center, that shows nothing in relation to the perimeter wall. I actually know the order of construction, so I know that the sheet piles were installed before the piles, and I also know that there is not a pile under that wall.

When you look at the entire sheet, the pile layout is crystal clear. It's simple, really. Piles are spaced 5'0" or 6'0" from the slab edge. The slab had a thickened edge per the detail shown earlier in the thread, 8' wide. There are no columns above this ring of perimeter piles; the thickened edge of the slab is carrying load which has been transferred down from the grade level slab, through the retaining wall which bears on the thickened slab edge.

Say it over and over again all you want, but that perimeter wall carried a non-zero load. Period. End of story. To continue to say what you're saying is ignoring facts. If you want to modify your position and say that the perimeter thickened edge/pile placement/retaining wall/grade level slab detail is a bad design, say that all you want and I don't think anyone is going to really disagree with you.

Put your ego away and LOOK at the detail thermopile posted above. That vertical block drawn at 5' OC from the edge of the slab, with a twin another 12" further in? Those are the piles dude. Note that there's not a column above in the section; note the hook bar tying the grade-level slab to the retaining wall.

None of this is that hard to figure out if you stop rambling about how smart you are and actually read the drawings.

Quote (Keith_1)

Nuke, you don't know where the ground is, there is an entire floor below that 2'2" elevation, you talk about being an idiot, you define it. Bottom of E-4 is 125' 8" to the top, learn how to add, it is a easy as 1+1=2

Again, seems like you're talking specifics without looking at drawings, or if you are actually looking at drawings, you can't read them. It's very clear what the basement TOS elevation is, and that there most certainly is not a secret hidden floor underneath it.



Just stop, man. You're embarrassing yourself.

Quote (Keith_1)

Demented, what is an Industrial Engineer? I honestly, don't know. It seems like a fancy title for someone that has a really vague job description, with absolutely no responsibility. IN terms of construction, waste water treatment is chemical, motors are electrical, air is mechanical, and structural is kind of self explanatory, so what do you actually have real word practical experience in?

One who integrates processes, equipment, streamlines processes, so on and so forth. So yes, it's a fancy title for a clipboard warrior/consultant. However that's not what I am and don't know why it displays as that for me when under my profile it states Manufacturing - Metal Fabrication/Welding, Fabricated Metals, Technician.

I never finished my Mechanical or MSE degree. I learned I'd rather build and play with the things I could engineer, rather than engineer them and learn to hate them.
What I have experience in? Mostly trolling while inebriated, Fabricated steel structures, Aerospace machining/welding/design, Bridges, and taking offense to being called dangerous. I do my very best in the field to check the work of guys like you so I can raise any red flag I can to prevent an issue. But eh, you can just call me a dumb welder. Nearly 23 years now of avoiding the stupid accidents/failures on sites that plague South Florida because straight C PE's think they're hot shit. Not a damn thing wrong with admitting fault or admitting you're wrong. We're all humans.

Take your damn blinders off man.

Quote (Keith_1)

...there is an entire floor below that 2'2" elevation, you talk about being an idiot, you define it. Bottom of E-4 is 125' 8" to the top, learn how to add, it is a easy as 1+1=2

Holy cow! You got something right! One whole thing right all by yourself! E-4 does go up to 125' 8"! Congratulations dude! Maybe we all owe you an apology! ... or something.

But wait! There's more!

Not only does E-4 go to 125' 8" like you said, but so does E-2, H-2, and H-4! And those four columns just happen to be where that big old air handling unit was located, 1' 6" above the roof! What a coincidunce!

Well it seems you taught this old retired electrician how to add and subtract and to read these old drawings perty good. Why don't you grab a shovel and measuring tool and show us that secret hidden floor below the parking level.

And through all of this, only one guy thought it was appropriate to call others names like dangerous or idiot and denigrate their job description. Up your game or go home.
I'm a little slow before my morning coffee, please, define "idiot" one more time for me.

I am from the land of clay soils and a monolithic concrete slab poured with reinforced thicker edges is common place here to support residential wall loads. I agree a 'Grade Beam' would have been a better solution to transfer the wall loads to the piles, but Champlain Towers was not designed by the Straight A over achiever PE, Architect and Developer Team.

IMO, the torsion load seems like it would be excessive where the wall keys into the thicken/reinforced monolithic slab on grade, from the patio deck loads. Along Building Integrity's Theory the thermal cycling would transfer stress to the edge joint of the slab and retaining / pool deck structural wall.

A good case for the retaining / pool deck structural wall should have been centered on a grade beam IMO, to transfer loads to piles. Then the Garage Floor Slab at grade should have been poured on top of that.

But then what do I know, I am too busy trying to outrun inflation currently...... Current Administration

Edit2.0: Perhaps someone could help with the difficult Math. The image below, is a Note on the S1 Structural Drawing. It states the Elevation of the Top of Pile Caps is EL. + 1'5", thus implying the top of the pile caps is 1'5" above the Reference Elevation. The Section View says top of garage slab is EL. + 2'2". Therefore if I performed the Laplace Transformation Correctly, then the top of the finished garage slab on grade is 9" above the top of the pile caps. Thus if the Edge of the Monolithic Slab Pour is 12", then the turn down portion of the monolithic slab is 3" deeper or lower in elevation than the top of the pile caps under the monolithic thickened slab edge.

Quote (Demented)

don't know why it displays as that for me when under my profile it states Manufacturing - Metal Fabrication/Welding, Fabricated Metals, Technician

When you join Eng-Tips you answer the questions shown on the screen shot below. The User Type Field is the field input that gets pasted by your Display Name, rather than your job, industry or job role.

@MaudSTL (Computer) 19 Jan 22 03:32:

Thanks for your kind words. I did a quick and dirty time and motion study of Mrs. Monteagudo's movements:



As you can see, there isn't much time for Mrs. Monteagudo do anything else. I think that the seven minutes between the pool deck collapse and the building collapse is not exact. I think that that there is some uncertainty and that time may be between 5.5 to 7 minutes, with 7 being a maximum. The time may actually be closer to between 6 and 6.5 minutes. I think the crack was close to the outside wall and may have been caused by column L9.1, as can be seen in the picture below of the second bedroom. The wall to the left of the column is the wall between the living room where Mrs. Monteagudo was standing and the second bedroom. As can be seen from the time and motion study, the crack reached her at about halfway between the pool deck collapse and the building collapse. Her apartment (611) is also about halfway from the top to the bottom. If the pool deck collapse caused the base of column L9.1 to no longer be supported, then the crack may have started at the top as the column separated from the floor slabs. The step beam at the lobby level also had a smaller section at column L9.1: it only had a vertical section of 16.5 inches between gridlines K and M. West of K and east of M, the step beam had a vertical section of 27.5 inches, so it stands to reason that of the three KLM9.1 columns, it was the weakest at the step beam.

I am from the land of clay soils and a monolithic concrete slab poured with reinforced thicker edges is common place here to support residential wall loads. I agree a 'Grade Beam' would have been a better solution to transfer the wall loads to the piles, but Champlain Towers was not designed by the Straight A over achiever PE, Architect and Developer Team.

I really do not understand why you would undertake the extra work for a ground slab, either the soil supports the load or it does'nt. If it is a span over a basement, then you would you just pour a few footings and place a grade beam across them,

I think your question is more about span lengths. In general, the max values of unsupported spans are (1) wood truss 14' (2) voided slab = 20' and post tension 30'.

It is not hard it is about distributing a load evenly onto a foundation.


I did a two thousand yard floating matt foundation one time, I started around 10:00pm and had 3 pumps with 2 trucks each until 6:00am, I got stressed because when the sun was about to rise and still had concrete on the way. This is not a thing you can key and do a cold joint.

IEGeezer,

Quote:

If the pool deck collapse caused the base of column L9.1 to no longer be supported, then the crack may have started at the top as the column separated from the floor slabs.

If the column failed at the bottom, would you not expect the first signs of detachment to appear at the bottom first? I would expect that as the column tore itself away from the floor slabs, they would fail progressively upwards.

cheers
tony

Quote (IEGeezer)

I think that the seven minutes between the pool deck collapse and the building collapse is not exact. I think that that there is some uncertainty and that time may be between 5.5 to 7 minutes, with 7 being a maximum. The time may actually be closer to between 6 and 6.5 minutes.

There’s no doubt that the Timeline estimates the time of key events, as the only true time stamps we have that are accurate to the second are the 911 calls. We do have several times that are credible, but not accurate to the second:

• 1:10 AM The Nirs heard what they called the first collapse. Sara Nir was WhatsApping and has a time stamp that she repeated in multiple early interviews.
• 1:14 AM Sara Nir went to the lobby to complain about the banging and so-called first collapse. She was still WhatsApping and it gave her a time stamp. Sara repeated that time in multiple early interviews.
• 1:18 AM The reported time stamp of the Adriana Sarmiento’s video of the garage.

You can calculate a fairly accurate time the building collapsed from Gabe Nir’s 911 call of 1:21:57 AM…and that’s assuming that the recording we have of that has not been edited. I calculated it once, but can’t recall what I came up with…if memory serves me it was something like 1:22:20-something.

We have no way to calculate an accurate time for any of the other main events. That’s why the Timeline uses ~, <, and > to indicate approximately, earlier than, and later than, just so we can derive a plausible sequence without claiming that we actually know exactly what time an event occurred.

Quote (Demented (Industrial)25 Jan 22 10:20)

you can just call me a dumb welder.

Demented, there is no such thing as a dumb welder, anymore than there are any "old, bold pilots"!

SF Charlie
Eng-Tips.com Forum Policies

Here is the timeline, 10 years ago there was a problem that everyone new about but were told it would be 10 million to fix it, which the Board thought would result in a few hundred dollars in increased fees, and that little sum posed a threat to their little fiefdom, so instead of loosing the only power that they have ever known in their entire lives, decided it was better pay a property management company $200,000 per year to tell everyone "it is all good we got an expert", because we paid a few hundred dollars and go PE stamp.

In my opinion, that PR, or any licensed person need to be criminally liable when something like this happens. You put your signature and a stamp and knowingly lie, your ass should go to the worst prison for the rest of your life.

It really pisses me off that so many "professionals" looked at this structure and knew that it was a structurally, and did nothing, simply because they made money to do so.

The pictures of those beams pre-failure, drive me f* crazy, that building official should be in the worst prison cell, and share a cell with a huge dude named tiny (play Berry white for effect)

There is a point where professionals need to be held accountable, I hate that the "stamp" actually provides no protection to people.

I'am not a troll, I just think you are misguided in where you are trying to assign blame, it is not with the architect, strutcrual or GC, it is the "professionals" after words that are at fault.

All they had to do was remove some pavers and reapply the membrane every 12 years, it is just like painting -- it prevents most problems, and is ultimately the cheapest thing you can do. It is not fancy like, new wallpaper, pool furniture which boards have no problem spending homeowners money on, but basic maintence is way out of the budget.

The "stamp" should be something that the general public can rely upon, and unfortunately they can't.

This thread should be a discussion amongst professionals, as to how we should self regulate and formulate a clear set of codes and regulations that punishes people that allow something this to happen.

Keith,

Which report from 10 years ago are you referring to? I'm assuming that'd be 2011? The Morabito report was 2018, so only 3 years prior to the collapse.

Also the membrane was repaired/replaced, twice. Once in the 1990's, once in the mid 2000's. As far as how well of a job the crews did, that was discussed previously and the quality of work was questionable at best, but still given the stamp of approval by the same firm both times.

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

Quote (keith_1)

It really pisses me off that so many "professionals" looked at this structure and knew that it was a structurally, and did nothing, simply because they made money to do so.

...

I'am not a troll, I just think you are misguided in where you are trying to assign blame, it is not with the architect, strutcrual or GC, it is the "professionals" after words that are at fault.

I'm having a hard time understanding why you're so insistent that:

1) Both the design and construction of this building were perfectly executed

2) The professional engineers who evaluated the building over the last decade somehow bear blame for the collapse

To the first point - I think it's relatively clear from first principles (and from the published opinions of consultants after construction, ie Morabito) that the entire design approach of the pool deck - horizontal suspended slab with horizontal waterproofing topped with topping slab/pavers/planters/etc while not making any provision whatsoever for drainage - was a huge design error. That's on the original architect and structural EOR, and is not the fault of consultants who evaluated the building later.

To the second point, the Morabito report released in 2018 is relatively clear, in my opinion, that rapid deterioration of the pool deck due to failed waterproofing (due primarily to an original design which was not sloped and included no drainage provisions of any kind, and secondarily to less-than-stellar maintenance after substantial completion of the building) was in progress, and needed to be addressed promptly if the progressive degradation of the slab was to be corrected. That report was also relatively clear that the previous attempts to repair structural concrete elements in the parking garage had failed, and that major repair to many garage columns, beams, and areas of the first floor deck were also urgently needed.

I don't think it's reasonable to expect that a consulting engineer who performs a building evaluation and provides his report promptly is also expected to be responsible for the execution of the recommendations in that report.

Bad design, half-ass maintenance, and terrible decision making by property management are the main factors in this disaster. It's possible that badly executed construction is a factor as well, although that is harder to know; when a final report is released we may know more on that front.

IEGeezer Great analysis on her steps and timeline inside her unit after awakening to the noises. But you left out 10 minutes to do the hair! LOL

AusTony2046,you asked:
"'If the column failed at the bottom, would you not expect the first signs of detachment to appear at the bottom first? I would expect that as the column tore itself away from the floor slabs, they would fail progressively upwards."

Construction materials do very strange things under stress. And the first column that I think failed was M11.1 outside the Nirs’ unit 111 patio, under the planter, and as shown in the tourist video, M11.1 was the missing column in the garage. Once that M11.1 fails you have the most added load stress on the columns L10 and M10, or as some people refer to them L 9.1 and M 9.1 above.

So at this point, the building isn't really collapsing but it is stressing and moving, likely shifting a little bit to the side, maybe sagging an inch or two, and so the crack Ileana Monteagudo saw on her Unit 611 living room wall was the result of this movement manifested in the drywall which is very weak, to begin with. The drywall is not strong, but the paper and under stress will crack easily.

So Ileana Monteagudo’s living room drywall likely just snapped a little bit and tore due to the movement of the building even though the building had not crashed yet. Maybe the building started to drop an inch and most unit drywalls are intact, but 611 is where the stress manifested itself. Look at the Ring video from 711, there were no cracks on the wall until it was collapsing as the camera cut out. Yet Ileana Monteagudo saw cracks 7 minutes prior, one floor down in 611.

One thing we can all agree on is most of the noise cracks and damage that people heard and survived happened in the "11 stack" of condo units.

I still believe that the first three columns to go were K, L, and M right under the 11 stack. Of units. So this aligns with everything that we have so far on this.
And remember AusTony2046, that we don't know that there weren't other cracks in other units not reported. There may very well have been cracks in Sarah Nirs unit we just don't know maybe the kids didn't see it maybe they heard the noise and just got out or didn't notice it. But we can't discount the fact that there must have been cracks in a few other units as well.

Quote (MaudSTL (Computer) 26 Jan 22 03:08)

I did not mean to question your timeline. I was focused on the "Seven Minutes" that the Miami Herald has published as the time between the pool deck collapse and the building collapse. I read but did not comprehend your previous comments about the 1:10 AM vs the 1:14 AM timing. Thanks to your comment, it is now clear to me that the time between the pool deck collapse and the building collapse may be as much as 12 minutes (i.e. from 1:10 AM to 1:22 AM). I was trying to come up with an estimate on when the crack formed in Apt. 611, based on Mrs. Monteagudo's testimony. However, I have a hard time expanding my time and motion study of her movements to 12 minutes. If you look at the video of the visit to Unit 611 on 17 July 2020, they walk the long hallway from the elevator hallway to Apt. 611 from 0:42 to 1:05, a time of about 23 seconds. I measured that hallway at about 83 feet in length, which at 2.2 ft/sec would take about 38 seconds (the elevator hallway is another 52 feet in length for a total of about 135 feet). That is the only independent measurement I could find of my time estimates.

I don't question the timestamps. However, there are 3 different computer clocks: Whatsapp, Tik-tok and the 911 computer. Nevertheless, I wouldn't think that they would have differed by more than a minute or so - not 4 minutes.

Quote (AusTony2046 (Electrical) 26 Jan 22 01:51 If the column failed at the bottom, would you not expect the first signs of detachment to appear at the bottom first? I would expect that as the column tore itself away from the floor slabs, they would fail progressively upwards.)

I can't disagree with you. Nevertheless, Mrs. Monteagudo's testimony is very credible that the crack formed from the ceiling to the floor and not the other way around. I was just trying to find some structural explanation of the witness testimony. It is devilishly difficult to try to reconcile the witness testimony to what was likely to have happened structurally.

Quote (IEGeezer)

I don't question the timestamps. However, there are 3 different computer clocks: Whatsapp, Tik-tok and the 911 computer. Nevertheless, I wouldn't think that they would have differed by more than a minute or so - not 4 minutes.

No worries. I didn’t think you were questioning time stamps. I just wanted to clarify what standards I used in assembling the Timeline from reported accounts. There are very few time stamps, but the good news is that they are in nearly perfect sync with UTC and with each other.

Computer systems use Network Time Protocol (NTP) to sync their clocks with UTC. So any variation among the WhatsApp, TikTok, and 911 systems would be in milliseconds (as a result of packet latency) rather than seconds or minutes.

>>>>>Edit:

Quote (IEGeezer)

…it is now clear to me that the time between the pool deck collapse and the building collapse may be as much as 12 minutes (i.e. from 1:10 AM to 1:22 AM).

Please have a look at the Detailed Data tab in the Timeline to avoid going down a rabbit hole. Based on witness statements, the crashing sound that the Nirs heard in 111 and Shamoka Furman heard in the lobby at 1:10 AM (which they called the first collapse) was not the same as the pool deck collapse at ~1:15 AM (which they called the second collapse).

Also…were you thinking about doing a time and motion study of Sara Nir’s movement from 111 to the lobby at 1:14 AM? There are links in the Detailed Data tab that can help you with what Sara stated she did. It might help estimate the time of the pool collapse better than ~1:15 AM. The Miami Herald House of Cards infographic shows their version of where Sara was WhatsApping in 111 before she left to go to the lobby.

Tonight’s Town of Surfside meeting will decide how much money the Town is willing to spend on their investigation. They seem to be moving away from “we want our own study ASAP” to “nah, we’re willing to wait for NIST.” From the Miami Herald, “Surfside shouldn’t cut ‘blank check’ for court-ordered collapse inspection, mayor says” https://www.miamiherald.com/news/local/community/m...

IEGeezer Yeah that drywall in Ileana Monteagudo’s living room failing from the ceiling down to the floor I think makes perfect sense in this scenario, because the southern edge of her living room where the sliders are or the windows is the location toward where many people theorized that the three columns that dropped initially in the collapse from the security video from 87 Park next door. That security video shows that the southern edge of the condo likely fell first.

if this is indeed the case in the southern end of the living room falls first, it likely was collapsing only an inch or two by the time Ileana Monteagudo saw the crack in her living room, and so the crack would start at the ceiling and work its way down to the floor, because the southern end of her condo is falling first.

@Jeff Ostroff (Electrical) 26 Jan 22 18:08

Quote (Great analysis on her steps and timeline inside her unit after awakening to the noises. But you left out 10 minutes to do the hair! LOL)

There is a difference between when the pool deck collapse happened and when the building collapsed. There is a consensus that the building collapsed about 1:22 AM, based on a 911 call. The difference arises based on whether the pool deck collapsed at 1:10 AM or 1:15 AM.

According to

Quote (MaudSTL (Computer) 13 Oct 21 13:37

We know that something fell loudly at 1:10 AM, and was heard from 111 and the lobby. We don’t know what fell or where it fell.

We know that Nico Vazquez and his wife Gimena Accardi were in the garage elevator vestibule just before the deck fell at about 1:15 AM, and they heard odd loud cracking sounds a few seconds before they got on the elevator. They were actually in the elevator when the deck collapsed. The Vazquezes did not state that they saw any debris in the garage before they got on the elevator. That’s not to say that a piece of ceiling couldn’t have collapsed in an area that they didn’t look toward. However, we don’t know what space they parked in or what path they walked to the elevator.

We know that the only witnesses (Sarah Nir and Shamoka Furman) who saw the deck collapse at about 1:15 AM saw it from the lobby, so they were looking at the parking deck near the lobby. Neither of them reported having looked past the parking deck at that time.

We know that Adriana Sarmiento and Roberto Castillero were in the pool area at the Bluegreen Resort, and heard the deck collapse at about 1:15 AM. They made their way over to the street and videoed the debris within the garage viewed down the garage ramp at 1:18 AM.)

According to the Miami Herald

Quote (Around 1:14 a.m., when witnesses were already hearing the first booms indicating the building was beginning to fail, a couple drove through the area where debris was later documented by Sarmiento. The rubble wasn't there at the time, nor did they report anything falling on their car. Although they reported hearing loud sounds, they saw nothing at all to explain the noise.)

The wonderful timeline that MaudSTL has put together is in agreement that the Nico Vazquez and Gimena Accardi drove through the garage before 1:15 AM.

If the collapse happened at about 1:15 AM, then Mrs. Monteagudo would not have had time to do her hair. If you have any suggestions how the time and motion study could be improved, I would be most appreciative.

EDIT: I am assuming that the pool deck collapsed at 1:15 AM or so and that the pool deck collapse and NOT the first collapse is what woke Mrs. Monteagudo up. The time and motion study is necessarily speculative, because it cannot be determined when Mrs. Monteagudo woke up. The rest of it is estimated, but not speculative.

Quote (MaudSTL (Computer) 26 Jan 22 21:42
Also…were you thinking about doing a time and motion study of Sara Nir’s movement from 111 to the lobby at 1:14 AM?)

There isn't enough detail in her testimony, but the distances to the lobby are the same. It would have taken her about 30 seconds to go to the lobby from Apt. 111. And about 30 seconds back to Apt. 111 from the lobby.

Quote (IEGeezer)

If you have any suggestions how the time and motion study could be improved, I would be most appreciative.

Your time and motion study exactly matches my understanding of Ileana Monteagudo’s movements, based on her statements. In her original interview, she said that she was awakened by a “supernatural force.” I think that was the deck collapse at about 1:15 rather than the big crash heard on the first floor at 1:10.

Correct me if I am wrong, but I find several things interesting in the design of the perimeter structural wall along the property line of Champlain Towers South, and some can not be maintained due to defective design. As BI said "Designed To Fail".

1 The bulkhead (sheet piles) at the property line is the backside formwork for the 8" perimeter wall. The bulkhead is corrugated, therefore you end up with part of the concrete wall filling this void when pouring the perimeter wall. I assume you have your nominal 8" wall plus concrete filling the corrugations in bulkhead.

2 From the pictures I have seen and the drawings it is not clear whether the patio deck slab pour is capping off the perimeter wall and the bulkhead or did the deck slab stop short of capping off the concreted filled corrugations between the bulkhead and 8" wall shown on plans?

3 Point being, if the deck slab does NOT cap off the bulkhead corrugated area, it leaves a lot of area for water infiltration directly into the concrete corrugate area fill and between the concrete wall and the steel bulkhead.

4 Next you have a concrete block privacy wall sitting on edge of deck slab which does not look to be water proofed, thus it lets water in on top of edge of deck slab, and traps that water inside the voids. It does not appear any water proofing was initially placed under block retaining wall on top of edge of deck slab.

5 Could the Voids were are seeing on the 97 Park side of wall be the gap between the edge of concrete block privacy wall and the corrugate concrete fill area of the sheet piles stopping at top of concrete perimeter wall below, but not serving as the formwork for the edge of deck slab when it was poured after the wall?

6 If so, then when 87 Park excavated up to their newly acquired properly line or the edge of the concrete block wall they replaced the sand that was on top of bulk head corrugated area with gravel fill? Was the bulkhead at the property line or was the 87 Park side of the Concrete block privacy wall the property line? Or was the concrete block wall sitting on mortar fill by mason on top of bulkhead corrugations such that half the block wall was on the deck slab and the other half was covering the bulkhead corrugated fill area? Either way looks like that area was getting lots of water infiltration, and garage pictures reflect that in the rusty pictures taken by one of the owners at her parking spot against that wall.

7 Enter 87 Park Construction and the thermal cycles of the patio deck, I would expect that the gap between the bulkhead and the concrete perimeter garage wall would enlarge at night, and shrink in the day, thus creating more and more opportunities for water entry and stress on the wall structure.

8 Moving down to the Thickened Turned Down Slab Edge Perimeter of the Monolithic Garage Slab Pour. The piles supporting the thickened area of slab at grade are spaced 12' apart, and 5' to 6' in from the edge of the thickened slab. Assuming soil bearing would not support perimeter wall loads directly, the tie into of the thickened slab, footer if you will, is distributing the load of the concrete perimeter wall to the slab. That means the perimeter wall is resting on a thickened slab that is cantilevered 5-6 feet from the piles. Thus seems like any vibrations next door would induce lots of movement along the South perimeter wall foundations? With all the water entry, would it be safe to assume there was soil erosion or displacement under thickened slab?

9 Sorry for the rambling thoughts, but I do not remember seeing any discussion of these issues, and find these issues very interesting. If not interesting to y'all then just punt these ideas.

Quote (thermopile)

Correct me if I am wrong... "Designed To Fail".

You seem to be asking the right questions but, without as-builts or other information on how these details were dealt with I don't think we can come up with the answers you are looking for.
I would like to add that the concrete block privacy wall was blown down at least once by a hurricane which may point to some initial flaws in the design or construction of this area, was well as the potential for insufficient repair methods contributing to water infiltration and structural degradation long before 87 Park came on the scene.

Nukeman, Thanks for the feedback.

Along the lines of thermal cycles and vibrational movement, the area of the patio deck that failed is the longest lightly braced span as others have pointed out. The pool braced one end of South wall, and the building that did not fall braced the other end. The deck that failed was between those two braced ends, which supports lots of movement, deflections, corrosion effects, and of course the pool curb had been raised and rebuilt, so newer concrete in that area of South Wall too.

New Video

Building Integrity

Surfside Condo Claims Engineer Failed to Warn Residents - Lawsuit Analysis Part 5 of 5
https://www.youtube.com/watch?v=FEwQAdSWBsE

The image of the Street between Champlain South and 87 Park, prior to Construction of 87 Park, clearly shows there was a concrete walk/curb, on the 87 Park side, up to the privacy wall of Champlain Towers South. It appears Champlain's South perimeter garage wall definitely had better water protection prior to construction of 87 Park than after concrete sidewalk removed and replaced with loose gravel fill.

So removal of that concrete walk/slab would have been very hard to do without damaging the privacy wall.

One would assume the concrete sidewalk sloped away from privacy wall and drained into street.

This clearly supports why there should be building set backs from the property line. Basically both property owners have that right to build right up to the property line it appears.

So where was the actual property line? Was it South side of corrugated sheet pile bulkhead, the middle of bulkhead, or the North side of bulk head?

Then where was privacy wall in relation to property line? Was is South side of wall, or was wall centered on property line?

In my state, private entities can not adverse possess land from a municipality, thus any encroachment by CTS probably did not entitle them to ownership of encroachment. However, in my state such a situation that had stood for years would be grandfathered in, and allowed to remain as long as it was never removed.

In addition, our state does not allow neighbors to shed their runoff on their neighbors. Properties typically have U&D set backs that are allowed drainage paths.

It appears 87 Park clearly was dumping water on their neighbor.

Quote (thermopile (Military)28 Jan 22 15:59)

... removal of that concrete walk/slab would have been very hard to do without damaging the privacy wall.

No, its not difficult to remove a sidewalk from an adjacent structure.

The gravel strip/boardwalk was a straight forward exchange for the sidewalk/asphalt pavement that it replaced. The gravel free drains through the substrate and has no impact on the adjacent property which hugs the property line.

I am working on a video now on the Forbes Ave Frick Park bridge collapse this morning in Pittsburg, not sure if you folks heard about that collapse.

Quote (Sym P. le)

No, its not difficult to remove a sidewalk from an adjacent structure.

The gravel strip/boardwalk was a straight forward exchange for the sidewalk/asphalt pavement that it replaced. The gravel free drains through the substrate and has no impact on the adjacent property which hugs the property line.

For skilled crews, it's easy. For the lowest bidder, not so easy. Pages 62 top 64 of the class action suite do appear to show damage caused by removal of that sidewalk. Water would definitely penetrate CTS from these points. This area of the building wasn't in good condition going back to the late 80's/early 90's, so definitely not the cause of the collapse, but without a doubt provided another hand in pushing the building past it's limits sooner.
https://ctsreceivership.com/wp-content/uploads/202...

Potato images for those who don't want to look through the PDF.

Thanks Demented, I've considered the damage shown by those images to be superficial. The construction detail as I understand it is that the sheet piles are driven, then the basement wall is poured to the inside of the sheets and capped by the slab. This concrete work is easy to finish and will be solid. The privacy wall then slightly overhangs the prior construction to create a finished line against the property and the lower overhanging portion is trimmed with block sections. This is not structural and can be (and was) refinished. When the slab fell away to the inside of the property, it broke away but left the privacy wall standing. Where the site was later stripped and the remaining portion of slab removed, the gravel sluffed in.

I have no reason to believe that the sidewalk removal might have damaged the slab or even remotely disturbed the sheet piles or foundation wall. Although Building Integrity made a pitch for slab tension compensating for failed column supports, and thus reason for perimeter damage to cause the collapse, I cannot agree with that extended reasoning.

A more damning image from the litigation is found on page 71:



Consider the following (green circle is 29/30):



Also, from page 60, if the east end of the property was settling, the vibration from 87 Park could be contributory.



EDIT X: Also, while I'm at it, all of the cracks that were readily apparent on the underside of the pool deck/parking slab would indicate significant topside cracks centered around each of the columns but hidden by the topping/tile work.

Battle lines being drawn. From the Miami Herald, Feds try to block victims of Surfside condo collapse from accessing crucial evidence.

Seems the Feds and the Miami Dade Police Dept suspect there's more to this event and they're wanting NIST to find that "needle" in the proverbial haystack.

NIST has known since they were first given their task that people were going to want to examine the evidence. They have had months to work out a protocol, and one can only suppose they were successful in this endeavor, given the amount of time they had.

Therefore, they should be ready to provide that protocol to interested parties. And, in fact, to any US citizen who wishes to see it.

They very well may feel that they should restrict/control access to this evidence. They by now should be able to articulate the level of that control. And where their interests are not damaged, provide access.

If they can't/won't do this, it appears they are stonewalling. I think I would even remove the "appears".


spsalso

NIST could take the samples for everyone, why can't they do that? Then it's still under their control, while they satisfy the pleas of the plaintiffs and defendants.

There's a few more details in this article -

Showdown in Surfside collapse saga, involving federal agency, could delay trial for years
Judge gave the parties 1 week to figure out evidence sharing

https://therealdeal.com/miami/2022/01/28/showdown-...

"NIST claimed exclusive control of the materials, citing a federal act, according to Goldberg, who also read the letter in court. But Goldberg countered that he “ripped through” the act and it does not give NIST exclusivity over evidence but mandates cooperation with others."

"Technically, the property belongs to the condo association, but the county’s police department has stored it, as it is doing its own investigation as well, Goldberg said."

"Miami-Dade argued in a court filing that if others are allowed to test the evidence, the county’s death investigation will be “compromised.” Hanzman denied the county’s pushback on the subpoena, mandating it to make all of the evidence accessible to the receiver and litigants."

Quote (Sym P. le)

Looking at your failure mode overlay area showing construction joints, and the fact that rebar is missing in pictures of construction joint near pool, and BI’s jump rope theory;

it would seem jump ropes in failure mode area between building and south patio deck wall, may have be carrying much of the deck load.

The construction joints allow failure mode area to contract and expand east to west with less restraint than the North-South expansion and contraction of failure mode area, thus contributing to deck sag and allowing vibrations to create movement in deck.

Thus the Vibrations and thermal cycles would appear to stress the overstressed areas even more till rebar starts popping from sagging slabs and stress relief at tops of skinny columns.

I won’t waste any more time trying to explain why removal of slopped concrete pad allowed more water into garage, as that may have been very small contributing factor to collapse.

Thanks thermopile, the explanation is elusive so once again I found myself thinking outloud. I find it peculiar that the only documented evidence of impending punch out was at the top of a column that didn't punch out. Moreover, although the approx. 30 foot span north to south may present an easy static calculation indicating weakness, the two way slab may have been facing its doom from forces playing the system at the east west margins.

Quote (Sym P. le)

…..the explanation is elusive so once again I found myself thinking outloud.

Keep thinking out loud, as your logic is ‘Spot On’, especially in lite of the information black out to the public!

Whoa just came across this lil gem -

Engineering Catastrophes: Miami Condo Calamity

Released January 26, 2022
Season 5 Episode 10

I just started watching it on Discovery+

Edit - 15 minute segment, nothing new... they only interviewed one former tenant from the West side of the building.

I recently learned that Discovery Channel had an 84-minute special on Dec. 4, 2021 (prior to the Miami Herald infographic) called When Buildings Collapse: Disaster in Surfside. I just watched it, and found that it features new animations, including a new animation of Mike Bell’s lever theory (without attribution,) and images from other building failures that are used to illustrate theories about the CTS collapse. They don’t get the timeline right. But they do have new interviews with Gabe Nir of 111 and Ileana Monteagudo of 611, which unfortunately provide no new information, Fiorella Terenzi (who provided the garage video tour,) and a host of various types of engineers and TV presenters.

Some more on cracked columns from the litigation and garage video:



The unknown location may be south face Column 76 (across the lane from 28) given the faded paint stripe on the floor (and carefully watching the garage video).

Edit: I've changed my mind about Column 76 but what looks like a faded paint stripe on the floor to the right of the column may be a clue:

Quote (Sym P. le )

I wonder if some of the horizontal cracks in columns are areas where columns were previously repaired?

The aux deck drain line to garage floor is classic of the lack of a designed in or maintained drainage system for patio deck, and what appears to be lack of storm water run off drainage system all together.

The aux drain serves only to keep caustic liquid from draining onto people or parked autos.

Thanks thermopile, NukeDude948, SwinnyGG.

Quote (thermopile)

From the pictures I have seen and the drawings it is not clear whether the patio deck slab pour is capping off the perimeter wall and the bulkhead or did the deck slab stop short of capping off the concreted filled corrugations between the bulkhead and 8" wall shown on plans?

Quote (NukeDude948)

That is correct. Also the drawings show piles on 12 foot centers supporting that slab around the entire perimeter to handle the load. Page 307 of 336 from the big set of drawings or page S1.

Quote (SwinnyGG)

When you look at the entire sheet, the pile layout is crystal clear. It's simple, really. Piles are spaced 5'0" or 6'0" from the slab edge. The slab had a thickened edge per the detail shown earlier in the thread, 8' wide. There are no columns above this ring of perimeter piles; the thickened edge of the slab is carrying load which has been transferred down from the grade level slab, through the retaining wall which bears on the thickened slab edge.

There is a good image by Robert Lisman in the Miami Herald Article "Did drilling next door damage Surfside tower? Newly surfaced vibration data offer clues" here:
https://amp.miamiherald.com/article255411881.html
archived here: https://archive.fo/22xyO

Using that image and others, it is possible to estimate the dimensions of the deck at the wall as shown below:
Yes, there is clearly concrete on both sides of the sheet pile in the areas where it is exposed.
But, even though the sheet pile was capped off the protection against salt water ingress would be lost as soon as the slab cracked horizontally.

The following are cropped from that image:
Notice in this section the deck has shared off:

This image shows the deck concrete between the sheet pile and the privacy wall above:

Here the deck has been fully retracted from between the top of the perimeter wall (basement garage wall) and the 4 foot exterior wall of the planter.

Clearly there was a horizontal crack between the top of the wall and the bottom of the deck.

I believe it is possible to show that the collapse of the deck started along this connection between the parking deck and the southern wall and I can explain why the concrete in that area was in such bad condition.

Quote (IanCA)

Wow IanCA you nailed it! You put together the as-built issues with the way they capped the sheet pile and that structural wall, and how water easily gets into space between sheet piles and concrete wall and via the corrugate fill.

This was the questions I had about southern wall and water intrusion and this clearly shows water intrusion was NOT a trivial issue at southern wall.

Edit: Last picture shows directly under planter at wall. It will take some time to fully absorb all the information presented.

@IanCA great post.

Raises some questions for me.

My own private working assumption had been that the initiator for the building failure was failure of the pool deck slab near the building, which put a horizontal load into the columns and 1st floor building deck (the garage ceiling/lobby floor) which they could not handle. I've also been operating on the assumption that the pool deck itself was not structurally critical to the stability of the building; in other words, I've been assuming this whole time that if you sawcut the pool deck level slab out and removed it right up to the edge of the building, without damaging anything of course, that the building itself would remain structurally stable. That may not be the case.

From IanCA's post, it's clear there was relatively severe degradation of the slab connection to the perimeter retaining wall. Is the failure of that connection enough to create a cascade all the way from the perimeter wall to the columns which ring the first floor deck of the building, in which case the catenary action of the pool deck slab created a horizontal load on the perimeter columns and 'ripped' them down? Or did the removal of the pool deck itself from the foundation system reduce the stability of the first floor lab below a safe level, even if that slab failed without putting significant horizontal load into the columns at the building side?

If there was severe water damage at the intersection exposed in the photo, would it be evident in the exposed concrete? How--is it something visible, or perhaps "tactile"?

I assume the rebar would show evidence of extreme corrosion right around the break. A close examination of those would be interesting. Would there be rust staining around the rebar?



spsalso

Quote (IanCA (Mechanical) 1 Feb 22 09:04)

The images posted by Ian were not in the immediate aftermath of the collapse. I agree that the lobby car park is a candidate for the trigger location but I would not read much into those photos as evidence (EDIT: of slab edge condition).

Note the screen erected along the walkway:



Various stills from two body cam vids (posted in no particular order) indicate a significant gap under the privacy wall where the slab pulled away.









Further west where the slab did not pull away and is not fractured. The slab edge is formed closer to the property line than I previously considered and the finish level of the sidewalk was likely several inches higher than the gravel strip.

Quote (thermopile (Military) 1 Feb 22 17:33)

Thermopile, what you indicate as a cold joint is not. It is a joint line in the form work.

Quote (Sym P. le (Mechanical)1 Feb 22 20:32)

Sym P. le, I can agree that cold joint looking horizontal line is just a formwork line. Since it has been painted it makes it even harder to tell.

I am posting 2 images below. Can you tell if these unpainted joints are:

A Cold Joints

B Formwork Joints

C All of the above.

Both look like form lines to me. The bottom is a form line 100%. The top one is less certain, but only slightly so.

Cold joints are never laser-straight. When you pour a joint with a cold joint in it on purpose, the cold joint is not tooled and finished, so the resulting bond line is not perfectly straight. It will be roughly straight, but there will be obvious jogs in it approximately the size of the aggregate, because the joint has not been tooled to drive the cream to the top surface and hide the ag.

When you pour something and there's an unintentional cold joint in it, the result is very, very obvious. Neither of those are an 'accidental' cold joint.

Quote (thermopile (Military) 1 Feb 22 21:29)

I am posting 2 images below. Can you tell if these unpainted joints are:

A Cold Joints

B Formwork Joints

C All of the above.

Context would be helpful. I see a joint between the two images.

SwinninGG, You are correct bottom joint in second image is only a B.

Now the upper line in the first image is a C.

The joint in the middle is the break point between the way the web site displayed the 2 images.

Sym P. le, My context is it very hard to tell the difference from the images we are analyzing. I know the history of these joints because I was the engineer and builder on this home project. In person, the difference is more obvious to the trained eye 👁

Quote (IanCA (Mechanical))

I believe it is possible to show that the collapse of the deck started along this connection between the parking deck and the southern wall and I can explain why the concrete in that area was in such bad condition.

IanCA, are you saying the roots of the shrubs in the planters had grown into the concrete structural slab below and broken it up into gravel over time?

In your first image showing the sheared of slab area, I can see the step in the driveway slab thickness vs the patio deck thickness.

Edit: I also like your theory that roots would break some of the masonry units below the concrete sideway on 87 Park Side, prior to removal of concrete curb/slab at 87 Terrace. So some of block damage could have been pre-existing condition under concrete cap.

The NYT interviews Surfside Building Inspector Jim McGuiness and others in The Towers and the Ticking Clock, which is focused on the impact of the CTS collapse on the Florida condo market.

Here’s a link to the archived version.

I could see Mayor Burkett being played by Clifton James in the movie, except he's no longer with us

Quote (thermopile)

are you saying the roots of the shrubs in the planters had grown into the concrete structural slab below and broken it up into gravel over time?

No, sorry, I was rather vague there. It is highly likely that the roots of the palm trees, previously located in the planter at the southern wall, caused cracks in the block walls of the planters and we know the waterproofing within the planters had previously failed, been repaired and failed again, in part from the Morabito report. The gravel comes from the beach path that was previously 87 terrace and was placed there during the development of 87 Park.

Here are my arguments for the failure of the slab initiating at the southern wall:

1) Very simplistically, think Ockhams razor, we can clearly see from the CCTV video shot from 87 Park that the collapse of the building progresses from the south to the north, therefore elements of the structure that are further to the south likely collapsed earlier and the location furthest south on the property would be the earliest and would be the connection of the deck at the southern property line wall. This also agrees with the witness statements suggesting the sequence was parking deck, pool deck, building.

Before the next point, let me say first that I very much appreciate Mike Bell's contribution to understanding this event and the skill and determination exhibited by Mike and his team in producing their animated videos. I believe that the rotation of the 1' 6" drop slab at the south of the building he depicts is very close to actual failure dynamics. Mike and I have discussed aspects of the collapse, but we didn't reach an agreement.

2) An initial collapse of a single column punching through, as proposed by many, including Mike Bell, has several geometric characteristics that reduce the probability of a progressive failure. Firstly, ignoring construction joints, an individual column is surrounded by 8 other columns. I suspect this means that the increase in vertical load on the adjacent columns may be as little as 12.5%. The deflection of the deck would require the deck to stretch in two dimensions (even in poor condition that deck was not very stretchy) to form a depression at the point of failure and the increased stress on the adjacent columns would be substantially lateral, horizontal, and each adjacent column would be backed up by several other columns beyond them. Consider a heavy object in the middle of a trampoline, the vertical load is translated predominantly into a lateral load shared by the horizontal springs who's deflection is mostly radial not vertical. Secondly, If a single column punches through, the geometry of the failure progression will tend to be concentric, radiating out from the first column. If that point is close to the building, then only a small region of the front involved in the collapse will initially reach the southern facade of the building and the bending moments or rotational torque on the 1' 6" drop slab will be relatively low and limited in area and in addition the debris from the parking and pool deck do not appear to exhibit signs of concentric failure.

3) If the initial failure begins at the southern wall, by the deck detaching from the wall, and encompasses the area occupied by the 8 vehicles, bounded on the east and west by construction joints or weaknesses running from south to north, then I believe it is possible to consider the approximate loads on the deck and column I14.1 at the south-east corner of the western portion of the building that remained standing as shown in the diagrams below.


4) If column I14.1 punches through the deck the load is transferred to column I14 but at a greater distance from the column and with an additional 23 feet of deck weight added. If column I14 punches through the load is further increased and transferred to column I12.1 The progression is linear towards the building and the progressive increase in weight allows a progressively larger area of the deck to be engulfed.

5) The possibility of a linear progression is reinforced by the deck failure line that runs east west through the parking deck gate.

I'm interested to hear whether that sounds feasible, whether it matches the evidence that was visible in the debris and the sequence of events.

Quote (Sym P. le)

The images posted by Ian were not in the immediate aftermath of the collapse. I agree that the lobby car park is a candidate for the trigger location but I would not read much into those photos as evidence of slab edge condition.

Thank you for your input and the body cam images, they are helpful and clearly show the gap left when the deck detached. I will look for some other examples of the edge condition soon after the collapse, but I don't feel as though the condition of the wall changed much from the time of the collapse to when the photo I referenced was taken. It is still in virtually the same condition now, apart from where the west portion of the building fell during the demolition.

Quote (thermopile)

this clearly shows water intrusion was NOT a trivial issue at southern wall

Thanks for your comments and I agree with your points about the water [chlorine, salt, and organic compound] intrusion.

Quote (Swinny GG)

in which case the catenary action of the pool deck slab created a horizontal load on the perimeter columns

Thanks very much. I believe that is true but the load is not entirely horizontal it is also rotating the drop slab and column connection. As the collapse progresses north the deck is impaled on an increasing number of columns so the required change in length could really only be accommodated by changing the geometry of the 1' 6" drop slab and column connection.

Quote (IanCA (Mechanical)

I'm interested to hear whether that sounds feasible, whether it matches the evidence that was visible in the debris and the sequence of events.

IanCA, Another Excellent post. Early on there were folks talking about parking deck and the many hours, days, months-and years of cyclic loading of that parking deck and how that was a very stressed area. Also there was discussion of cracks and possible damaging repair solutions.

👍

North Tower gets temporary shoring


https://www.kansas.com/news/business/article257966...


EDIT 2: I just watched some of Mike Bell's Animations that IanCA mentioned. Here is link to part 3, which is very interesting to me.

https://youtu.be/WdkdIUdJLEk

Quote (IanCA)

…witness statements suggesting the sequence was parking deck, pool deck, building.

There are no witness statements supporting a deck collapse sequence. No surviving witness actually saw the deck collapse. All the surviving witnesses who saw the deck after it collapsed only saw the parking deck, either from inside the lobby or from the porte cochere as they escaped and ran to the street.

The first survivor to see the deck after it collapsed was Sara Nir of 111, who was in the lobby at the time, talking to Shamoka Furman the security guard about the loud crash they had heard at 1:10 AM. When they heard and felt the deck collapse at about 1:15 AM, Sara ran over to the lobby window next to the parking deck and saw that it had collapsed. The MH House of Cards infographic does a good job of depicting the view from the lobby window. It shows that that in the dust and darkness there was no way to see beyond the parking deck from the lobby.

Sara assumed there had been an earthquake, and ran from the lobby down the hallway to 111 to evacuate her kids. Gabe Nir of 111 was in the kitchen cooking salmon when the deck collapsed and dust started rolling in through the open patio doors. As the building rumbled and swayed, he ran to the bathroom door to roust his sister Chani, who had just taken a shower. They both made it to the apartment door by the time Sara got back to them, and all three ran back to the lobby.

While Sara was coaching Shamoka on what to say to 911, the Vazquezes exited the elevator (where they had experienced the collapse) and were met with panic and clouds of dust. They had no idea what had happened until they ran outside and saw the collapsed parking deck as they escaped. Gabe ran outside to the porte cochere and only then saw that the deck had collapsed. He ran back inside to roust his mother and sister, and then they ran across the street and up the block before the building collapsed.

Shamoka remained at the security desk, calling 911, fielding calls from residents, and telling them to get out.

According to her husband, the late Cassie Stratton of 410 was awakened by the building shaking rather than by the deck collapse. When she got up and went to the balcony, she saw that the pool deck had collapsed and water was pouring out of pipes. Mike Stratton says she called him at 1:20 AM, fully five minutes after the deck had collapsed.

>>>>>Edit: None of the surviving witnesses, including the Nirs, Vazquezes, and Shamoka Furman, talk about hearing or feeling a multi-stage deck collapse sequence. Ileana Monteagudo of 611 said she was awoken by a “supernatural force.” Adriana Sarmiento, who shot the garage ramp video at 1:18 AM, said they heard a loud crash and felt the air pressure forced out of the garage.

I agree with the failure starting at the south wall. I mean, it makes sense. It also occurred with a car parked above it right? To me it makes sense that the weakest point on the south wall is where the planters and car are. And moving to the north from there we have the design flaw caused by the change made in deck height and elimination of the beams that would have been under the planters. This progresses towards the building to the north and failure occurring at planters outside 111.

Cantilever of the beams / drop slab at planters. Enough damage has been done.

So then what was the solution? Expansion joints dividing building from outside deck? Those parking garages are a real problem. Nobody ever considers a parking deck to be a structural risk. Why on earth would you run a beam from a building column to hold up a planter box? Nobody ever thought this would be a problem?

Quote (IanCA (Mechanical) 2 Feb 22 07:55)

If the initial failure begins at the southern wall, by the deck detaching from the wall...

There has to be a mechanism that allows for the slab to be pulled off of the wall. Either the slab edge moves north or the wall moves south. The wall does not move south so the slab has to move north and the only way for that to happen is for the collapse to initiate further north in the parking area around the columns.

As I've further considered your previous images, I've realized that there are three failure modes along the southern edge and I propose the following:






Note the diagonal scratches in zone B:

My understanding from IanCA’s posts was punch shear at I14.1 could have started the deck ride?

He also proposed the slab detaching from the perimeter wall as the initiation point, which is what I was responding to.

Sym P.le,

Ok, understand. I think I14.1 punch shear more likely, in agreement with your post.

Hopefully I've helped to clarify what was happening at the south perimeter. If so, it was a useful exercise.

Sym P. le, Yes your excellent posts explained why we have 3 different zones of slab failure, and the pulling diagonally of middle section clearly supports first movement being parking deck, and it cascading from there. I think you and IanCA explain the linear progression of failure from somewhere around I14.1.

To correlate the deck collapse sequence under discussion to the witness statement timeline, after over two hours of banging sounds heard in 111, the first big crash was heard at 1:10 AM by the Nirs in 111 and by Security Guard Shamoka Furman in the lobby. Is it conceivable that what they heard at 1:10 AM was the the rebar failing as I14.1 began to punch through the slab? If so, could this occur without visible collapse in the garage?

The reason I ask is because the Vazquezes have said nothing looked out of the ordinary in the garage when they parked in the garage and walked to the elevator just before 1:15 AM. Unfortunately, we don’t know what space they parked in, so we don’t whether a small local collapse of a delaminated ceiling layer, if one occurred, would have been within their line of sight.

We do know the Vazquezes heard unusual, loud cracking sounds in the seconds before they got into the elevator. To relate to the theory under discussion, could this have been the failure of the Zone A connection as the deck collapse began?

The Vazquezes were ascending to the first floor when the deck collapse occurred at about 1:15 AM. So the deck collapse occurred within a few seconds of the loud cracking sounds they heard just before they entered the elevator.

Quote (Sym P. le)

There has to be a mechanism that allows for the slab to be pulled off of the wall

Thanks very much for taking the time to add additional notes.

I agree, and I have attached an image below showing what I believe to be one possible explanation for how the deck detached:
This is a sectional elevation through parking space 45 looking west.



I believe this satisfies all of the available evidence.

Quote (MaudSTL)

To correlate the deck collapse sequence under discussion to the witness statement timeline

Thank you very much MaudSTL for taking the time to summarize the sequence of events in your post at 20:34 and for relating events to the sequence under discussion at 03:11. It is going to take me some time to think through your comments and to try and line things up in time. As you can see in my post at 06:07 there are several places where rebar and concrete could have been slowly failing and causing the banging sounds heard for two hours before 1:10am.

Quote (Sym P. le)

Zone A: Slab is pulled north off the south perimeter wall

Yes, correct, but there is one slight adjustment required to your plan view, please. Zone A should also encompass parking spaces 46 and 47, and is centered on column I14.1, along with the blue ellipse being centered on column line I.
Thanks again.

Here is the article from the Miami Herald yesterday https://amp.miamiherald.com/news/local/community/m...

The Herald article is showing actual photos of the just-added shoring poles that Champlain Towers North Condo, the sister building to the collapsed condo had installed last week. I will be doing a video on this in the next couple of days, I'm still working on the 2nd Pittsburgh bridge collapse video. This to me is a major shift in thinking about the current safety of the surviving sister condo. As you know engineer Allyn Kilsheimer had mentioned back in July that he thought the building was safe enough that he would allow his kids to be in it. So now here they are putting up shoring poles around the columns in the garage so they must know something you don't just add a dozen shoring poless around a column for no reason.

So CTS felt they needed to relocate the majority of their parking and thus applied for a permit... as far as I remember there wasn't a number of spaces listed on the permit application. If it was only a limited number of spaces like CTN, they should have just bypassed the permitting process and had Morobito shore up parts of the garage?

This is of course guess work as neither party is speaking atm. But just from the paperwork we've viewed.

Quote (IanCA)

It is going to take me some time to think through your comments and to try and line things up in time.

I greatly admire your thorough, logical approach. To simplify the correlation of your detailed theory with the timeline, here is a screengrab of the key perceptions for your convenient reference. I understand that we cannot truly know how to correlate all structural failure details with the witness statements, but there does need to be some logical connection between the events proposed in the structural theory and what witnesses say they perceived.

Thank you so much for your efforts.

Quote (MaudSTL (Computer))

I greatly admire your thorough, logical approach.

Ditto, Ditto, Ditto........

That shoring in CTN clearly indicates that someone (presumably having seen the survey of the concrete/rebar condition there) is worried about punching shear. Not in the place that you are now suggesting was the trigger though (near the southern perimeter wall).

But iirc (from one of the BI videos I think) the plans of the way the columns support the deck and ground floor parking area are different and that part of the CTN deck is not as poorly supported as it was in CTS.

Along Sym P. le's Diagonal movement of deck, would this portion of broken slab also indicate the diagonal movement?

It would seem it takes punch shear of a column further from South wall than planters, to pull the slab totally away from South wall?

I can see how a break under inner planter lifts the end of slab, but I would expect to see a horizontal crack in the step part of the edge of slab where the deck slab caps off the sheet pile. See IanCA's 1 Feb 9:04 post diagram of as built conditions.

Back to image, does the stamped concrete area indicate we have back and forth lateral movement like the card table situation, prior to punch shear or as columns are punching and creating load transfers?

Or was stamped concrete pushed up in accordance with IanCA's planter fail diagram?

Or is raised circled stamped concrete support IanCA’s planter failure even more. Being slab in circle ⭕️ is pulled North first by drop at planter near South wall?

That piece was pushed up by the column that punched through. Trying to apply more meaning to that seems like a fruitless endeavor.

Quote (LionelHutz (Electrical))

Here is a view that shows the the entire part of the deck that detached from the wall.

The wall behind the parking area showed damage on the opposite side as well.

As fruitless as this may be, if you zoom in on the passenger rear tire of the black pickup truck, from the image Reverse_Bias posted above, it sure looks like the deck is broken under planter wall in this area, and it appears passenger rear tire is in a deeper depression of the deck. Almost like the truck is loaded with bags of Sakcrete in the truck bed or something very heavy?

Truck also appears to be parked much closer to wall than surrounding autos? It was mentioned early on, that perhaps truck hit planter wall???

I remember asking that early on, I think even before we had the garage video.
I think at the time I thought the wall was continuous, from the bottom and that the planter being pushed back or backed into could have dislodged the slab from the wall.

Closer images, actually that looks to be a hard cover for the truck bed that's been dented in.
But you can see the chaos of the planter box.



[img

A better zoom into that back tire
https://res.cloudinary.com/engineering-com/image/u...]

My guess for the truck is a 2018 2500HD High Country Duramax. If so, they don't get much heavier than that. Someone else posted about the truck but I lost track of the post.

Look at the top tension crack in Optical98's post...

Sym P. le

There were some posts about a Duramax possibly hitting a column, and I always thought they meant in the garage...but yeah, it could have hit that column from above as well. I'll look thru my pics to see if there's any that show the front right fender area of it.

Zoom in>

Quote (thermopile (Military)4 Feb 22 01:01)

I was wondering if that slab wrapped over the vehicle below. The stalls underneath are very deep and from the garage video you can see that sometimes the vehicles are parked all the way in and sometimes not.

It's all good new input to the overall question, but we don't know what that the deck has fallen onto. Cracks in it now may be due to landing on uneven stuff (cars, etc) under it.

Quote (Optical98 (Computer)4 Feb 22 01:27)

The poster I was referring to was trying to approximate the weight of the vehicles.

I edited my post, check the pic and zoom in...there actually is a mark on it's fender. Can't say for certain what and when.... but it's there.

The more I stare at the photos around the Duramax, the more I see IanCA’s slab failure in this area, and the fact that it looks like that is sufficient to pull slab down and away from wall. It was a 2-way slab, and I think that could explain tension failures in top and bottom in same area. Planters are a lot of weight, and provide great water source. I also see failure moving South to North explaining unzipping of rebar as failure progressed North. Failure likely progressing from Duramax area traveling North and East together, like a Wave 🌊 for lack of coming up with better term.

I think this fits timeline and witness statements well. Any sound in this area is close to elevator shaft, would seem to be a conduit for sound to travel to every floor.

A wave traveling South to North would create high pressure to vent thru openings like North like Parking gate.

Quote (thermopile (Military) 4 Feb 22 15:26)

I have to agree. The evidence seems to make a sound case for the lobby parking area, if not the truck itself, to be the trigger for the collapse.

Note: the line indicated as a construction joint at the west side of my drawing is an error. The topping layer broke in a straight line but the slab beneath has not.

Quote (IanCA (Mechanical) 3 Feb 22 07:08)

Zone A should also encompass parking spaces 46 and 47, and is centered on column I14.1, along with the blue ellipse being centered on column line I.

I would include space 46 in zone A and shift the ellipse to the west while also making it broader. Space 47 would likely be akin to zone B. Thanks

You need to be careful about looking at the positioning of that truck in these photos - that's after the deck has already settled and it looks like the car on the W side of the truck has fallen into it, it could have pushed it into the column as they both fell. Nudging into that column (which we know didn't collapse) wouldn't have caused anything to happen anyway.

I think slab was already about to, and Duramax just happens to be double weight of midsize to smaller cars, so like parking two cars on top of each other. A little more weight or the last straw on camel’ 🐫 back.

I feel may have been construction joint near where Duramax parked

I was thinking more along the lines of the weight and live load aspects working on an inherently weak slab/column connection. That little car would be a mere fly splat on that truck.

The damage seen on the outside of the wall at the planter is proud to the plane of the wall. What could cause that aside from a lateral (normal) force pushing south from the other side? Am I missing something?

I think it is falling down under inner planter wall in IanCA’s (c) diagram above. The downward fall creates horizontal and vertical force vector components on slab.

Say rebar has failed East to West under inner planter wall, but North South has not. But under stamped concrete East West rebar has not failed.

Further I would expect a lot of stamped concrete water ends up in joint between stamped concrete and inner planter wall and keeps structural slab under planter soaked and if already sagging deck with low spot at planter wall, them gravity does the rest

Quote (thermopile (Military))

Say rebar has failed East to West...

That makes sense. Thanks.

I’ve attempted to map the Parking Deck Failure Theory onto the Witness Observations from the Timeline. Please review and provide corrections to this draft.

Maud, I am thinking first cracking noises may be slab under inner planter wall failing. I think that area drops creating punch shear at I14.1 next while tearing East as well. Clearly later rebar shears at South wall could be gun fire type noise.

There is so much reflected sound in a concrete structure, and shifts in sound as it reflects.

In general though, I think current evidence supports the spirit of witness statements, but very hard to tie exact events to specific statements. Perhaps more thought needed?

It’s a theory. We can project logical options that will not pin anybody down.

It's a decent theory, it holds more merit than the pool deck just collapsing on it's own one night.

Are we certain all 3 of the 10.1 columns failed? I thought we'd found some of them (the bases) still upright in later analysis. Just something to double check on.

I agree we need to tie it to the statements as best we can, without suggesting they "didn't know what they heard" etc.

I wonder if this new joint protocol will include the Town of Surfside. From the Miami Herald, Parties in the Surfside condo collapse lawsuit could soon gain access to evidence from site.

>>>>>Edit: Here’s an archived version.

Quote (Thermophile)

…thinking first cracking noises may be slab under inner planter wall failing. I think that area drops creating punch shear at I14.1 next while tearing East as well. Clearly later rebar shears at South wall could be gun fire type noise.

Can there be a five minute gap between the planter area dropping and the punching shear that brought down the deck?

We have to think about the loud crash at 1:10 that was followed by rumbling and the deck collapse at 1:15. The tricky part is that whatever happened at 1:10 was not noticeable to the Vazquezes down in the garage right before 1:15. So if it broke through into the garage, it would have to be of limited size.

This level of detail is why I think it’s a good idea to talk about all the logical narratives that could make sense within the context of the theory.

Maud, I wish other folks would chime in too. I think it is possible the slab broke under inner planter wall and fell or sagged some distance, prior to progressing further. Perhaps a little time delay?

I do too. I come from a field where there’s no penalty for brainstorming solutions. I have the impression that structural engineers don’t feel comfortable doing this.

I was imagining that if the rebar under the inner edge of the planter started failing earlier in the evening, the pull on the slab that ultimately tore it off the south wall could be gradual. At 1:10, some of the the Zone A connections to the south wall could have failed and made that loud crashing sound. The edge of the Zone A slab section could have balanced on the top of the garage wall for five minutes until enough load was transferred that the slab punched through I14.1 at 1:15…and then it all went down fast in the paths we’ve theorized.

Maybe someone else can imagine a different narrative that would make more sense.

Maud, I think you have a good narrative, based upon evidence we have. I have a feeling that slab was source of noise heard a day or two earlier as it sagged and cracked.

Why Radio Silence from IanCA?

Thanks. I’ve mapped the narrative onto IanCA’s annotated drawing for the sake of discussion.

==> IanCA, I’ll delete this if you like.

Quote (thermopile)

Why Radio Silence from IanCA?

Sorry about that thermopile, I really appreciate all the feedback and ideas. I had other commitments I had to deal with. I am keen to get back to this and will provide specific responses and additional information later this evening. I think all of the additional diagrams and markup add value.

Elena Blasser in 1211 heard those cracking sounds between 3 am and 4 am the night before, and remember, what seemed loud and local to her could have been anywhere, as sound travels readily through solid materials.

The sound Elena heard could have originated from the pool deck planter right outside Sara's Unit #111, or it could have been from a few floors below Elena, or because of the solid slabs, it could have been a few units over and down.

Have you ever been in a multi-story building near a railroad track when the train passes by? You can feel the vibration, it travels up the columns of the building and across the slabs.

2500HD Duramax. Where's the zoomed in pictures of the fender badges that prove that one? At least post the picture of the amber roof lights that truck would have.

If the collapse and knocking sounds did start near the back planters on the parking deck it's hard to believe none of these people went out on their balconies to look what was going on until after the collapse. Those planters are at least partially visible from every balcony in this picture and a lot of them are closer to it than the Nirs who reported the knocking sounds.

@MaudSTL @thermopile, thank you for your kind comments.

Quote (MaudSTL)

To simplify the correlation of your detailed theory with the timeline, here is a screengrab of the key perceptions for your convenient reference.

Thanks, MaudSTL, much appreciated. This is helpful and I agree with your later post:

Quote (MaudSTL)

I’ve attempted to map the Parking Deck Failure Theory onto the Witness Observations from the Timeline. Please review and provide corrections to this draft.

I would like to share another observation related to the dust which is mentioned several times in the witness statements.

In several photos, including the one posted by thermopile on 3 Feb at 22 23:35, the column at the transition from the 8-foot wall along the pool deck, to the 4-foot wall by the planter is much lighter in color than its neighboring column to the east, as shown in the cropped images below. Notice the East side of both columns is brown in the first image.




Credit JoeRaedle Getty Images
I first noticed this back on October 30th and it took me until Nov 3rd to come up with a good explanation. I think it is simply dust causing the lighter color, both columns are the same color again in later photos after it has rained. But the dust didn't come from the collapse of the building, because both columns would be equally exposed to that dust. I believe it most likely came from the pile of rubble below the column and was blown vertically by the air being exhausted from the garage as a large section of the pool deck collapsed, coinciding with the air pressure described by Adriana and Roberto at ~1:15. I believe that the air pressure was caused by the rapid reduction in the volume of the parking garage. I don't think there would be as much dust on that column if the failure had progressed from north to south. I suspect the dust adhered to the column because surfaces were wet following the rain the afternoon before. If the failure had happened first near the building then later to the south, dust in the parking garage near the building would have been blown north towards Adriana and Roberto. But they didn't mention dust and it doesn't look dusty in their video. For me, the dust is another big topic in itself. Why was there so much dust? I think it was caused by the chemical action of acids produced by salt and pool chemicals (exhausted in that area) leaching calcium compounds from the concrete (seen forming what appear to be stalactites in the garage tour video - not the cylindrical injection ports with flanges) leaving a very weak powdery concrete behind.

I hope that helps.

I will try to catch up on responses to other posts tomorrow.

@Reverse Bias:

Well, it was dark, and looking straight down on a scene where not much horizontal shift had occurred, it might not be obvious from above that anything had happened directly below.

Having said that, I think it likely that at least some of the occupants of the west part of the building were out on their balcony/ies looking for the cause of the "first" crash when the building came down. Perhaps they have been told not to talk to the press?

OT, what is "stamped" concrete and how does it differ from the concrete under the pool deck?

Quote (AusTony2046)

I think it likely that at least some of the occupants of the west part of the building were out on their balcony/ies looking for the cause of the "first" crash when the building came down.

The Nirs in 111 were saved by the fact that they were all awake. I think what saved Ileana Monteagudo in 611 is that her balcony door was open when she went to bed. She was awakened by the sound of the deck collapsing.

Many people in Florida sleep with their hurricane-reinforced windows closed and sealing out the sound. The fire department employee watching TV on the 12th floor didn’t hear the deck collapse or feel the building shake…he heard the building collapse and compared it to a jet. The Gonzalezes watching TV in 904 lived by being awake and having incredible luck, not having heard the deck collapse nor having felt the building shake…they started running to the hallway from the bedroom as the building actually collapsed beneath them. What woke Cassie Stratton up in 410 was the building shaking after the deck collapsed, not the the sound of the deck collapse. This may also have been true of others. Adriana Sarmiento says that there were people on the east end of the building who came out onto their balconies as she videoed at 1:18 to see what was going on. She told them to get out, but they couldn’t hear her and were out of time.

Quote (LionelHutz (Electrical))

At least post the picture of the amber roof lights that truck would have.

Lionel

Apparently you have never spec'd and ordered a custom 2500 truck. Those amber roof lights are an option, and not on ever 2500. My son's build to order 2500, does NOT have amber roof lights. Perhaps some states require them, but they are not required by any of the states in our area.

Edit: A quick Duck Duck Go, yields clearance lights are DOT requirement on commercial vehicles 80" wide or wider. It appears single rear axle 2500's are slightly narrower than 80", whereas all dually trucks exceed 80", therefore have cab roof lights.

Except California has rules against cab lights on some 2500's..... Therefore state by state rules under 80".

Quote (Reverse_Bias)

If the collapse and knocking sounds did start near the back planters on the parking deck it's hard to believe none of these people went out on their balconies to look what was going on until after the collapse. Those planters are at least partially visible from every balcony in this picture and a lot of them are closer to it than the Nirs who reported the knocking sounds.

The person I would like to ask is the security guard. No one has ever asked Shamoka Furman if she was able to hear the banging sounds in the lobby. We do know that she heard the loud crash at 1:10. It is my understanding that the sound of rebar breaking travels through the structure more than the air. If that is so, then it makes sense that people on the first floor would be more aware of it. Various early interviews did say that people were used to hearing all kinds of banging from the roof work that was going on. But that would have been in the daytime.What made Sara Nir go to the lobby to complain is because the loud crash occurred at night.

IanCA, your concrete deterioration along South wall due to pool chemicals is interesting as to why concrete at south wall perhaps failed from chemical reactions, and perhaps just let go of rebar at first. The pool curb and top edge was rebuilt in the past. Perhaps partly due to pool chemical failure or the fact that they were raising the patio deck height by decking over the old pavers. Lots of poor operational and maintenance decisions going on. BTW, I wish I had worded my radio silence better, as I was trying to thing out loud to brainstorm what I think your complete theory is, and I really looked forward to you either confirming some of my thoughts or pointing us to your complete logic.

I am not an expert in anything, but I have been exposed at a broad band of technical disciplines. Master of nothing, jack of trades sort.

I would like to add that frequency of sound determines transmission thru building materials, and that at lower frequencies standing waves can form that reinforce some frequencies and cancel some frequencies.

Lower frequencies transmit thru concrete type building materials better than higher frequencies.

Edit: IanCA, I believe I am following your logic on initial event under planters at transition between slabs and privacy wall transition.

I am seeing tension reinforcement in bottom of 13” slab not lining up with tension rebar in bottom of 9-1/2” slab, and possibly a construction joint at slab transition.

I will just wait for your complete logic and evidence to flow.

Missed my point completely. But why expect any reality to be followed at this point?

Lionel,

What is your reality? Whether that truck is a 1500 or 2500, it is still significantly heavier than the average small auto, so a lot more load capacity next to I14.1. If Diesel Engine next to column then definitely more weight than a gas engine....

2500's are typically longer than 1500's by foot or so. That truck looks very long to me, and if someone took dimensions from that column to planter wall, and looked up spec on GM trucks, they could determine if 1500 or 2500.

I reference the 'Fly splat' the auto next to the truck made on it, when it slid into the truck during the collapse. Sorry Sym P. le for reusing, but I loved that analogy!

Quote (AusTony2046 (Electrical))

OT, what is "stamped" concrete and how does it differ from the concrete under the pool deck?

AusTony, both the stamped concrete topping slab and the patio deck pavers are finish floor materials and NOT structural members, like the 9.5" or 10-1/4” structural slabs below patio deck and parking deck.

We know waterproofing was not in original build under either topping material, but we know it was added under patio deck over pavers.

The poured stamped concrete slab was most likely poured directly on top of structural slab without any water proofing layer at all.

The reality is that there was a diagram which illustrated how the deck could have pulled away from the wall. Parlaying that into a complete theory that explains how the building must have collapsed starting at a pickup truck has no basis in reality. But, as I already posted there has been enough wild theory chasing already that has been claimed to be provable that I wouldn't expect it to stop now.

From what I see in the pictures, all I would conclude is that there is probably something under the collapsed deck holding up the deck under the middle of the truck. The pictures show nothing that could prove where the collapse started. It could have just as easily ended up like that with the collapse starting from the right side of the diagram.

Lionel,

I agree something under slab could be holding partial areas up, however I have not seen any other pictures where structural slab had the break features that IanCA has pointed out in this area. In other words I don't think deck falling on car, broke the deck.

We are talking a weakened slab ready to go at any minute with the slightest nude. The truck is just double the live load in that parking spot than the average small car would be, so a little more load on the camel's back.

As far as truck, what we need to know is if that truck was parked there the day before or was that the first time it was parked there. I don't see IanCA saying truck is the cause, clearly it is one of the point or distributed loads in his diagram of loads in that area. He was just trying to estimate the total load on the structural slab in a static condition.

What is your theory for the collapse?

Quote (LionelHutz (Electrical)5 Feb 22 05:25)

The hood scoop indicates Duramax, the width of the rear passenger door indicates crew cab and the front grill indicates High Country trim, at least to the best of my Googling ability. That is to say, a 6000lb vehicle or two modest vehicles parked atop each other sans bug splat.

I agree that all should be mindful not to extrapolate extraordinary theories from generalized photographic evidence.

P.S. Googling is a term covered by spellcheck.

Quote (AusTony2046)

OT, what is "stamped" concrete and how does it differ from the concrete under the pool deck?

Hello @AusTony2046,

Following on from thermopile's post above, there are good images in the 2020-10-14 Board of Directors minutes approved, uploaded here by SFCharlie (Computer)(OP)7 Sep 21 16:29

Link

It is worth looking at the original document, specifically page 43 of 83, because the images embedded are high resolution and you can copy and paste into any image processing application then zoom in.


The image of Core B, and notes below it, confirm there was no waterproofing on the parking deck. Something doesn't seem right to me about the last piece on the right labeled B5, it appears to be tapered, the top surface looks smooth and the color appears different than the section above. But the fact that the deck had delaminated meant that the yield strength of the connection of the rebar to the concrete was substantially reduced below its design value, right?

Quote (AusTony2046)

Well, it was dark, and looking straight down on a scene where not much horizontal shift had occurred, it might not be obvious from above that anything had happened directly below.

Good point, I completely agree.

Quote (thermopile)

Or was stamped concrete pushed up in accordance with IanCA's planter fail diagram?

@thermopile I believe that the displacement of the stamped concrete you mention agrees with the idea of the initial failure occurring at the connection of the parking deck to the southern wall.

Quote (LionelHutz)

That piece was pushed up by the column that punched through. Trying to apply more meaning to that seems like a fruitless endeavor.

@LionelHutz Please refer back to the post by Sym P. le (Mechanical) on 2 Feb 22 21:07 and the annotated image of the southern wall. If zone A begins to fail before zone B then at some point in time zone A will be lower than zone B, but they are somewhat connected, certainly through the pool deck gate, and columns in zone C have not yet punched through. The surface of the deck is retained in the East and inclined down in the East West direction (lower in the West) as well as being lower in the south. This would likely pull the deck (and stampcrete) on West side of the deck closer to the column as the deck rotates down. But the size of the section lifted really depends on where the stampcrete cracked.

In conclusion, I believe there is information there and it agrees with the failure modes being proposed.

Quote (LionelHutz)

The pictures show nothing that could prove where the collapse started. It could have just as easily ended up like that with the collapse starting from the right side of the diagram.

@LionelHutz
Let's try to reach an agreement by considering the information presented so far. We can select two candidates for the initial point of failure and compare the likelihood that the selected region or point would lead to progressive failure and eventual collapse of the North-East portion of the tower. Let's compare the theory I am advocating, that the initial point of failure was the connection of the parking deck (zone A) to the southern perimeter wall, with the theory that the initial point of failure was column K13.1 punching through. I have attached a document with the comparison of the details as I understand them. Please feel free to correct any errors or add additional information I have missed.

@LionelHutz
Here is the link to the file:
Link

Quote (thermopile)

IanCA, your concrete deterioration along South wall due to pool chemicals is interesting as to why concrete at south wall perhaps failed from chemical reactions, and perhaps just let go of rebar at first.

I'm pleased to hear that. I will provide further information as time permits.

Quote (thermopile)

BTW, I wish I had worded my radio silence better,

Your comment was completely reasonable and resonated with me. Over.

Quote (thermopile)

I am not an expert in anything,

I think it helps to have a range of experience and exposure to different engineering and science disciplines. So you can be proud of that.

Quote (thermopile)

I would like to add that frequency of sound determines transmission thru building materials, and that at lower frequencies standing waves can form that reinforce some frequencies and cancel some frequencies.

Lower frequencies transmit thru concrete type building materials better than higher frequencies.

Thanks for this input. This will come into play more when considering the effect of vibration caused by driving sheet pile.

Quote (thermopile)

I am seeing tension reinforcement in bottom of 13” slab not lining up with tension rebar in bottom of 9-1/2” slab, and possibly a construction joint at slab transition.

I am not sure where the transition you are referring to is located, can you provide an image or drawing, please?

Quote (thermopile)

I will just wait for your complete logic and evidence to flow.

I hope that the document I posted in response to LionelHutz will help to explain more of my thinking on this aspect. It was also written with you in mind.
CTS Initial Failure Compare Link

Quote (Reverse_Bias)

Here is a view that shows the the entire part of the deck that detached from the wall.

@Reverse_Bias, Thanks for adding that image. It is very similar to the one by Chandan Khanna first published by the NY Times on 7/3/2021 archived here but the version you posted has a slightly better angle on the wall.

Quote (thermopile)

if you zoom in on the passenger rear tire of the black pickup truck, from the image Reverse_Bias posted above, it sure looks like the deck is broken under planter wall in this area, and it appears passenger rear tire is in a deeper depression of the deck. Almost like the truck is loaded with bags of Sakcrete in the truck bed or something very heavy?

I agree, the rear wheel has dropped far enough to allow the deck to come into contact with the underside of the sill. I don't think there is additional weight, just that there was insufficient strength in the concrete deck, to the south, to support it.

Quote (thermopile)

Truck also appears to be parked much closer to wall than surrounding autos? It was mentioned early on, that perhaps truck hit planter wall???

Agreed, more to follow.

In trying to guess where the initial failure of the pool/parking deck happened, I like to consider which columns were most heavily loaded. Because of the spans, column K-13.1 appears to be the most heavily loaded by a long shot. It is almost 38% more loaded than I-14.1, about 36% more loaded than I-14 and about 17% more loaded than K-15. If we assume deterioration was roughly equal everywhere and barring meteorites, any theory about the initial point of collapse would have to explain why a more lightly loaded column would fail/punch through first. Not only is K-13.1 more heavily loaded than I-14 and I-14.1, but I-14&14.1 are bigger columns. Thus, I would think that gridline K was more likely as an initial point of failure than gridline I. Following is a diagram showing the tributary areas for each of the four columns:



Here are my rough calculations of the dead loads:

https://res.cloudinary.com/engineering-com/image/upload/v1644099527/tips/Load_Calculations_ianneg.pdf

EDIT: There is an offset towards the west of 3.5 feet as you go south from column K13.1 to the one I have labeled as K15. So K15 is not on gridline K. This offset is labeled on Sheet S2 of 14 with the 1-17-80 revision of the original Breiterman drawings. These are the "Basement Level Dimensions." It should also be noted that gridline 15 is 8 inches south of gridline 14.1. There are a lot of offsets in the column spacing that are interesting and make calculations difficult.

The parking slab thickness of 10.25 inches that I used in the calculations is taken from a Morabito core. The change in dimension of the slab from the pool deck to the parking deck I haven't found in the original drawings. For calculations purposes, I have assumed that the slab changed from 10.25 inches to 9.5 inches along the north south gridline defined by the column I labeled as K 15, which is not on gridline K. It's a guess.

Consideration for weight of vehicles?

Following is a quick and dirty of the loads in the areas between the tributary areas for columns I-14.1 and K15 and the wall. The planter weight is included in the overall dead load. Most of the planter weight would be on the wall and thus not loading the slabs. I still don't see how the failure could have started at the wall.

Rough calculations:

Quote (Sym P. le)

Consideration for weight of vehicles?

That would be in the live load of 60 lbs per ft². I didn't include it in the diagram, since the live load would be even everywhere but it can be seen in the calculations. The factored load uses 20% for the dead loads and 60% for the live loads.

IanCA,

Thanks for your responses to my questions/thoughts out loud. I just got back to read your white paper comparing two theories. The longer lever/moment arm tugging at 1’6” step down in building slab is interesting concept. I am having hard time visualizing how the slab punch shears progress. The long lever arm indicates at some point in time, the deck has punched thru all deck columns prior to hitting garage floor, such that at some moment in time, the whole deck is tugging at I/K/l/M 9.1 at same time. That implies deck failure at South Wall progresses East-West prior to the wave going South to North.

Perhaps I am not following your logic correctly?

@thermopile - I don't see any reason the deck would be high in that area unless something is holding it up. Skyhook I suppose?

@IanCA - It seems pretty clear to me that the piece circled was lifted in the corner by that column which punched through.

Lionel, I am not disagreeing with you about something being under the slab on North side of break. Per IanCA’s drawing there are two tension breaks in slab in that area. One on top and one on bottom. Question is did those breaks occur before slab landing on garage floor, or after part of slab landed on say an auto below, with the breaks occurring from a cantilever situation?

Quote (IEGeezer)

If we assume deterioration was roughly equal everywhere...any theory about the initial point of collapse would have to explain why a more lightly loaded column would fail/punch through first....Here are my rough calculations of the dead loads:

@IEGeezer, Thanks very much for contributing to the discussion on this topic. It is important to study all viable objections or alternatives to their conclusion. There are several ways in which I can predict, and show, that the deterioration was dramatically worse at the connection of the deck to the southern perimeter wall. Thank you for taking the time to compile the data and share your calculations. The figures look reasonable to me.

Quote (IEGeezer)

I still don't see how the failure could have started at the wall.

Thanks for the additional details extending to the wall that is helpful. Please can you describe or sketch how the deck wall connection will fail if you increase the dead load to the point of failure? Or the condition after collapse of the deck at the wall if K13.1 is the initial point of failure?

Quote (thermopile)

Question is did those breaks occur before slab landing on garage floor, or after part of slab landed on say an auto below, with the breaks occurring from a cantilever situation?

Yes, thanks thermopile, that is the critical point. My perspective is that it is not possible to achieve the conditions we see unless the deck cracks first in two places and detaches from the wall as a result.

Quote (IanCA (Mechanical) 3 Feb 22 06:07)

Quote (IEGeezer (Industrial) 5 Feb 22 23:23)

There is simply no reasonable means by which the planters along the south perimeter can cause this collapse.

Ian, I appreciate your enthusiasm but this is a non starter.

Geezer, thanks for the calcs but they really weren't necessary.

Quote (IEGeezer (Industrial) 5 Feb 22 22:23)

It's good to see some numbers but I struggle with design calcs used to evaluate failures. We have here a specific case where the load is not spread evenly so for evaluative purposes, wouldn't it be better to run some numbers that recognize the known warts such as the uneven weight distribution of in situ vehicles. Even if the numbers still indicate that the building should have remained standing, we might start to appreciate where things deviated from norms. In this case, there was no mythical live load, only static loads.

Quote (IanCA)

Please can you describe or sketch how the deck wall connection will fail if you increase the dead load to the point of failure? Or the condition after collapse of the deck at the wall if K13.1 is the initial point of failure?

Professor Lehman assumed a 9.5 inch slab everywhere. Morabito apparently made 5 cores: A, B, C, D, E and F. A, E and F show a 9½ inch slab. B and D show a 10¼ slab. C shows a 10½ slab. If the slab under the parking deck was intentionally built thicker, then that may or may not invalidate professor Lehman's model. I don't know. I have not found a specification for anything thicker than 9½ inches in the original drawings. For the deck to fail at the southern wall first (i.e. without any punching shear in the interior columns), I would think that the only way that could happen is if the deck failed in shear at the wall. A thicker slab for the parking deck would make that less likely. There would also have been a much smaller actual live load on the pool deck.

For the wall to pull out like it apparently did would be difficult to explain unless the interior columns failed in punching shear first, causing a catenary that would clearly have pulled the deck away from the southern wall, like so:

It is difficult when looking at something forensically whether it is cause or effect. Is the deck pulling out from between the southern privacy wall and the supporting wall cause or effect? I'm leaning towards effect.

I don't necessarily think that a shear failure at the southern edge would propagate so easily to the north. A shear failure at the southern wall would I think reduce the load on the columns immediately to the north, thus maybe arresting a progressive collapse (or leading to a different kind of collapse where the interior columns fail due to an unbalanced moment rather than in punching shear). Punching shear failure of the interior columns, on the other hand, would, as the diagram above shows, make the steel reinforcement act as a weighted cable that will tug at the extremities (slab doesn't disintegrate, but stays relatively intact). Thus, the deck pulls out of and off of the southern wall and away from the building, perhaps damaging certain building columns when it pulls out. For that reason, I favor punching shear failure of the interior columns and K 13.1 seems to be the most highly loaded one.

I agree with you on K13.1, especially since the small column footprint would concentrate the impact of shearing forces. I hesitate though in that a known decrepit slab may have been vulnerable to a special case scenario such as an excessive point load from a heavy truck. A punch out at K13.1 could propagate through the parking area sooner than the pool deck.

Quote (Sym P. le)

Geezer, thanks for the calcs but they really weren't necessary.

The calculations have helped identify column K-13.1 as the most severely loaded column in the vicinity of the collapse.

Quote (Sym P. le )

It's good to see some numbers but I struggle with design calcs used to evaluate failures. We have here a specific case the load is not spread evenly so for evaluative purposes, wouldn't it be better to run some numbers that recognize the known warts such as the uneven weight distribution of in situ vehicles. Even if the numbers still indicate that the building should have remained standing, we might start to appreciate where things deviated from norms. In this case, there was no mythical live load, only static loads.

According to Morabito's Sheet A2C-1.0, the parking spaces in the area that we have been focusing on are approximately 10 feet wide by about 18⅓ feet long. Column I-14.1 would only have had 2 parking spaces in its tributary area. If you assume that you have a heavy vehicle and a sedan, the actual load for those two parking spaces would have been about 10 Kips in the tributary area for column I-14.1. Because of where the axles would have been (due, in part, to the planters), I don't think the weight of vehicles would have been attributed to the wall tributary area. So the vehicles would not have, theoretically, contributed greatly to the loads at the wall, but I would have to double check that. The thicker slab and that Column I-14.1 is bigger than K-13.1 should have helped.



One of the reasons I have focused on the pool deck is that the dead load for it is about 168 lbs per ft², whereas the parking deck's dead load is about 171 lbs per ft² or almost the same. Yet, the parking deck is thicker and has bigger columns. Columns K-13.1 and K-15 should have been the same size as the parking deck columns.

Quote (Sym P. le )

A punch out at K13.1 could propagate through the parking area sooner than the pool deck.

I wish I could have stated it so clearly. That is exactly the point.

Thanks Geezer, I was referring to the planter area calcs as not being necessary. The others I find useful. My concern about the weight of the vehicles is their potential impact at the slab/column connections to which they are adjacent in addition to any slab deflections to which they contribute.

I agree with you that columns K13.1 and K15 should have been considered as supporting the parking area in the original design.

Quote (IEGeezer)

For the deck to fail at the southern wall first (i.e. without any punching shear in the interior columns), I would think that the only way that could happen is if the deck failed in shear at the wall.

Please can you try to explain to me why you would think it would not be possible for the deck to fail in the way I depicted in the image shown below:

Quote (IEGeezer)

For the wall to pull out like it apparently did would be difficult to explain unless the interior columns failed in punching shear first, causing a catenary that would clearly have pulled the deck away from the southern wall, like so.

Thanks very much for the diagrams I find it helps the discussion. The columns we are talking about are 24"x24" columns, aligned on I, that supported the southern portion of the building that remained standing. The columns absolutely did experience some lateral deflection as witnessed by the cracks in the stucco at the south and north corners, but I have not seen any evidence to suggest that the deck was displaced somewhere between 8 and 16 inches to the north as it would need to be to allow the deck to detach from the wall.

Here are my thoughts about the three cases you illustrated:

Quote (IEGeezer)

Is the deck pulling out from between the southern privacy wall and the supporting wall cause or effect? I'm leaning towards effect.

I don't see enough room or flexibility to allow the deck to retract at least 8" without there being at least two cracks (and I mean lines of structural failure) in the deck. We can see one of those cracks in the photos and the debris matches the presence of the other.

Quote (IEGeezer)

A shear failure at the southern wall would I think reduce the load on the columns immediately to the north

Surely if the deck detaches from the southern wall the load previously carried by the southern wall would then be carried by column I14.1, increasing its load.

Quote (IEGeezer)

will tug at the extremities (slab doesn't disintegrate, but stays relatively intact)

Can you estimate the lateral displacement at the southern wall, please? I think it is probably fair to say that reinforced concrete slab or deck doesn't usually disintegrate. But we can see that the conditions in this case are unusual and the concrete did disintegrate. Please see the area of the image highlighted below:

Quote (IEGeezer)

Column I-14.1 would only have had 2 parking spaces in its tributary area.

Unfortunately, the parking area encompassing spaces 44, 45, 46, and 47 had weaknesses on both sides. Certainly a construction joint to the west and probably one also to the east beneath the planter running south to north to the pool deck gate. Is there a way to explain the rotation of the planter wall and fence in the foreground of the image below, if the initial failure is column K-13.1?

That condition can be explained by failure initiating at the southern wall because there are multiple cracks in the parking deck (a large diagonal crack is visible behind the silver Honda) and the southeast corner is able to rotate down, lifting the north end of the wall up and right, before the column below punches through.

I completely agree that the columns on K should have been 24"x24" to support the parking deck loads, but I would also include K-11.1.

Quote (Sym P. le)

There is simply no reasonable means by which the planters along the south perimeter can cause this collapse.

Please can you tell me where was the weakest region of concrete in the structure prior to the collapse and why?

Remember, none of the professional and experienced individuals who visited this property in the past 4 or 5 years felt there was any imminent danger, including the city inspector who visited the day before the collapse. So we are actually looking for something that would not conventionally be considered reasonable or expected.

Quote (Optical98)

Closer images, actually that looks to be a hard cover for the truck bed that's been dented in

Thanks very much for those images, much appreciated. I hadn't noticed the apparent hole in the wall in the channel 7 screen shot.

The explanation I have for the hard cover being dented in is perhaps that Ileana Monteagudo and/or Shamoka Furman stepped on that surface, and fell, while trying to reach the street. They are seen/heard standing right there in one of the police bodycam videos and Shamoka says the lady is injured.

In one of the previous threads there was a linked document where someone was trying to pin blame on 87 Park (before the whole lawsuit set of videos in this thread). One of the points made in there was suggesting that the series of images you're talking about again suggested the collapse initiated in that surface parking area - iirc either K13.1 or K15 was implied. I don't remember exactly when but if that rings a bell for one of you and you can find it quickly it's worth revisiting.

I think any rotation in the final orientation can probably be explained by falling onto an uneven surface underneath i.e. the part on the right of that image landed on a car and the part to the left didn't so it is lower and rotates the fence. Those tension cracks could be due to the loss of support after a column punches through rather than the cause as well, couldn't they?

I'm struggling to see how the slab could be pulled off the deck if it was sitting on top of it (which seems to be the case from the diagrams earlier). Even in @IanCA's diagram, it is far from pulling off entirely. Only after it punches through the 14.1/15 line would the geometry for that work for me.

If we're looking at this area of the building it seems more likely to me that the slab was starting to punch through, that was being restrained by the horizontal rebar at the wall/slab connection (providing catenary tension), and when that rebar failed it meant the punching shear was high enough to completely fail. Probably at K13.1 because all the calculations (@IEGeezer's the other day and those summarised in a BI video a few months back) indicate that is the most highly loaded and also one of the small section columns. That would then put a lateral load on the slab/wall joint and could pull it off, and the redistributed load would immediately cause a punching failure at the other columns under the deck (which were all highly loaded already).

What I'm not sure about with this idea (any of the "collapse started near the south of the deck" variants) is how it lines up with the Vazquezes not seeing anything in the garage when they drove in, or most of the reported "I heard noises" coming from the x11 stack. Yes, sounds are moved around in a concrete structure, but surely the people in the SW part of the building would have heard those noises more loudly if the initial failure was at the wall or even K13.1.

It would appear the relationship between location of pool chemicals, the ventilation fans in garage, and robust water source, would point to direction of weakest slab areas due to chemical reaction. Then there are natural designed in weakness like construction joint locations along this path, as well as other inherit weaknesses.

Is the box identified by the speech bubble, a potential exhaust point for ventilation fan?

EDIT: To clarify my Sakcrete comment in bed of Duramax truck. The reason the passenger rear side suspension is fully compressed is most likely just axle articulation from drivers rear tire dropping and hanging free.

A Diesel engine means that front axle is a lot heavier tire point loads than the rear axle tires. Assuming no live loads under bed cover.

Edit2: Just like roof flashing at parapet walls, any water proofing membrane under patio blocks, has to be turned up flashed and counter flashed at planters to prevent joints between finished toppings and planter walls allowing water entry. I see no evidence of that flashing system, and sagging deck due to planters drains water to this area.

Quote (thermopile)

Is the box identified by the speech bubble, a potential exhaust point for ventilation fan?

Yes, that is exactly what that is. The ductwork is shown on sheet 22 of 336 in the 1979 plans.
There is a 30x10 duct from the pool equipment room to EF-23 via a 19x19 opening on the pool deck as shown below:



But the detail for the opening on sheet 33 of 336 (S2 of 14) was inaccurate because there was a dimension missing for the distance of the opening from the wall:


Which would make the framing detail shown on sheet 38 of 336 (S11 of 14) difficult to follow


We already know that the atmosphere in the pool equipment room was detrimental to the concrete from the photos taken by the pool service guy a day or two before the collapse. I acknowledge that the loose concrete in the pool equipment room had been removed in preparation for repair, so it looked somewhat worse than it would have otherwise. But the effects of the chemicals are still significant.

Quote (Red Corona)

Even in @IanCA's diagram, it is far from pulling off entirely.

@ Red Corona, thanks for your input. That diagram was at a time fairly early in the sequence of events I am proposing. I will create another showing the positions later in the sequence.

IanCA, So we have interrupted rebar at opening, that could be in a line under inner planter wall and great location for chemical reaction to concrete

Quote (thermopile)

So we have interrupted rebar at opening.

@thermopile Yes, but as far as can see on sheet 31 of 336 (S5 of 14) the bars in the deck along the wall were on 12" centers, so it would be one or two bars, top, and bottom.

IanCA, Understand not many bars but if also a N-S or E-W construction joint in area, coupled with chemical reaction in area, things get very interesting in this area.

And missing beam from design change

Quote (Red Corona)

I don't remember exactly when but if that rings a bell for one of you and you can find it quickly it's worth revisiting.

@Red Corona, Thanks for the suggestion. I suspect you are thinking about the post by IEGeezer (Industrial) on 20 Aug 21 04:34 in Part 11.
The linked document is here:
Link

I will review that information again in detail.

I don’t see how we avoid considering the effect of South Planter distributing loading on slab that translate to an increased load on slab connection at I14.1 of K?

Quote (thermopile)

IanCA, Understand not many bars but if also a N-S or E-W construction joint in area, coupled with chemical reaction in area, things get very interesting in this area.

And missing beam from design change

@thermopile, I completely agree, that's why I removed the word "only" from my post. It is all too easy to neglect, or downplay, this part of the structure because it wasn't taking the building loads, "there was nothing under that wall", "the wall wasn't taking any load", all it has to support is 4-foot high CMU wall, it is easy to understand why people think this area is insignificant. Plus that area was damaged when the 8 foot high pool deck privacy wall collapsed during hurricane Wilma

Quote (Penagwin)

Penagwin (Computer)14 Jul 21 18:29
Just found another video I haven't seen mentioned, it's from a video of a Hurricane Wilma in 2005.

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

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

@IEGeezer,
Looking at that image I'm not sure what material strengths to put in for my calculations. Any suggestions, please? I see one piece of bar that pulled out, it looks as though the rest, were missing, already failed or sheared off due to embrittlement.

It was back on August 20 (in Thread 11) that IEGeezer (Industrial) theorized that the initial failure point was Column K13.1

Quote (IEGeezer (Industrial))

Based on the measurement of the weight of the planters I think that the probable point where punching shear first developed was column K13.1, followed by K12.1 as shown on the attached Sheet titled Level 1 Demo Plan and identified as Sheet D2C-1.0 from the Morabito bid documents referenced in my prior post.

Quote (sgw1009)

sgw1009 (Computer)6 Feb 22 18:36
It was back on August 20 (in Thread 11) that IEGeezer (Industrial) theorized that the initial failure point was Column K13.1

I am having a hard time seeing the deck slab failing in punch shear first at an internal column, due to Building Integrity’s tight jump rope grid analogy of rebar grid in slab.

Unless there is a shear of rebar on all sides of column at same time.

Quote (thermopile (Military) 6 Feb 22 18:15)

I don’t see how we avoid considering the effect of South Planter distributing loading on slab ...

Because the planter is continually supported by the wall and has no ability to impart significant bending moments to the slab.

Quote (thermopile (Military) 6 Feb 22 15:25)

... the box identified by the speech bubble ...

Nice catch!

If I can draw an analogy to wood framing, a piece of lumber is not wasted because of a knot provided that certain limitations are met. Similarly, holes can be drilled through floor joists provided that certain limitations are met. Also, an opening for stairs in the floor diaphragm of a house is typically provisioned with double joists on either side and a double header on each end. Likewise, the duct opening in the slab is provisioned with additional rebar to accommodate the loss of continuity. Thus it is an interesting anomaly, given its location, but not a smoking gun. It does help to isolate the two failure regimes, zones A and C, but note Geezer's identifying that the concrete in zone A would be thicker than the concrete in zone C which would also isolate the two regimes.

I need a lot more help before I believe the corrosion driving the collapse theory. (Edit: along the south perimeter wall)

Quote (IEGeezer (Industrial) 6 Feb 22 02:56)

What if 3 tons were applied to a single quadrant or 4 tons to half the surface?

Quote (Sym P. le (Mechanical)6 Feb 22 22:18)

Because the planter is continually supported by the wall and has no ability to impart significant bending moments to the slab.

Sym P.le, thanks for feedback. I can see that loads near the south wall do not contribute to increasing bending moment on say I or K columns as much, and mostly add shear load on wall. However, at the Zone A and B transition area there does appear to be a change of state if your will in the concrete. The Core Sample also indicates this 'peculiarity' at bottom of deck slab.

I did some reading up on pool chemicals, and how they control the pH and the chemical effects on concrete from the Portland Cement Association.

I will attach that pdf, if anyone else wants to read it.

Even a Blind Squirrel gets an acorn every now and then.........

https://res.cloudinary.com/engineering-com/image/upload/v1644187678/tips/is536-types-and-causes-of-concrete-deterioration_umzezc.pdf

Concrete and rebar can suffer a lot of abuse by chemical action but deterioration does not dictate complete failure.

A quick calculation shows that for a 25 foot span to pull 8" off a support, the far end would have to drop almost 6 feet. To borrow Geezer's catenary sketch, this would be easier to accomplish if a line of multiple columns punched through as opposed to only the closest one and suggests that a broad area of punch out was required to pull the slab in zone A off the south perimeter wall. The lowering of the lobby parking into the garage level may have been graduated by a succession of failures rather than all in one go.



Edit: In keeping with this, we do not know if witness accounts reflect one or more, or which event in a sequence.

a rough and ready stereo 3D garage image with one frame from the USA today video and one from the TikTok video. Hint: concentrate on the far items, not the gate.



I'm reupping the video's in case anyone can improve on this. Attached USA Today video:

• https://files.engineering.com/getfile.aspx?folder=6bb8ec48-cd79-41f8-8a5d-c

Tiktok video

• https://files.engineering.com/getfile.aspx?folder=31182d6a-e65e-498b-9927-8

Sym P. le, I confirm your 6 foot drop at far column. I came up with 5.74'. But then I decided what if break in slab is at 10 feet from wall. When I did this, it only took 3.16 to 3.6' range drop at break to pull slab off wall. If slab has two opposite breaks, seems the drop would be even less to retract slab from wall. A V-shaped Fold if you will as seen on after collapse damage around rear of DuraMax

Quote (Sym P. le)

…we do not know if witness accounts reflect one or more, or which event in a sequence.

Although there is a gap of about five minutes between the first crash heard on the first floor at 1:10 (which apparently did not cause noticeable debris in the garage) and the deck collapse at ~1:15, the witness statements we have in the Timeline do not describe seeing or hearing a deck collapse sequence. They all describe hearing a single, very loud crash when the deck collapsed at ~1:15, rather than a multi-stage deck collapse.

Quote (Sym P. le (Mechanical))

a rough and ready stereo 3D garage

And don't forget to look cross-eyed until you see three images with the one in the middle being 3D. There is a deleted post which I missed. I will say there are some planters there but that's about it as far as recognizable items. Albeit the parking deck would not be that far east. right? Is the point what can't be seen? At one point it was claimed by someone that car(s) are visible along the perimeter south wall. I think I felt that was true at the time. But that's a lot of staring cross-eyed, and it hurts after a while.

I threw it up in case it triggers some creative brainstorming.

Got it. I am thinking single seminal loud crash heard by pool attendees across the street from garage entrance. After that thought, I don't know in light of the south wall failure theory. It probably put things into focus but it's not coming to me. This theoretical wave progression could have happened so very quickly. That's a problem.

Could be something reflective bifurcated by the gate. Another thought I had which probably isn't worth much is that if 13.1 punched first before the section along the wall then you would not be able to see any cars along the back wall. And there was a general feeling that I recall when these images were being looked at ad nauseum, that the back wall and car or cars were visible. Of course this suggest that the pool deck area had not completely collapsed yet when the tic toc video was made. Because I can't quite imagine how you could see autos along the back wall if the pool deck was as low as it is in the final collapse. But that's a lot of unconfirmable crap too.

If tail lights, where along back wall is that auto? Was someone in that auto or could initial rubble fell on car and triggered lights to come on due to impact with auto? Does this suggest collapse started from West side of that auto and perhaps North of that auto?

Quote (thermopile (Military) 7 Feb 22 02:28)

M11.1 is already awol in the image from all apparent examination (although some seem to question that). So I tend to lean toward the idea that no cars can be seen along the back wall and that any claim of such is spurious. It's just to tempting to imagine what one wants to see. Useless exercise beating a dead horse IMHO. Depending on how you adjust the levels of contrast and brightness you can get to the point where there appears to be a pile of concrete back there and probably just the deck sloping down from back to the wall. I see that in one of Ostroff's videos. 3D depth doesn't help much.

Edit: I will just say I am not certain about anything. If part of a car is actually visible and it could be ascertained that's what it is amidst the concrete I suppose it could have some implications but I just can't imagine it. In the final state after collapse I don't think cars in the garage are visible from above from any photo I have seen (before the controlled demolition). There were cars visible after that so you have to be careful when a photo was taken. This almost seems outside the bounds of reasonable speculation. No shortage of that in the history of this thread.

What I don't see is a full thickness of slab laying on the garage floor. That leads me to wonder if the debris in the lane way came from slab collapsing on either side. The slab above the lane way beyond 27 is stiffened by the BMA's on either side and the slab drop half way into the bay. To the east, there is no slab drop and to the west, the slab drop is closer to the building so not as much stiffening. I find it hard to believe that 11.1 is missing and am still expecting it to appear in the shadows. Concrete columns don't seem to have a history of vaporizing, only exhibiting crush but otherwise still standing and in this case punching clean through the slab.

The shiny object is in the USA Today video and is rather nebulous throughout the video. It only vaguely appears in the Tiktok video.

Has anyone been able to synchronize the videos. The amber flashing light reflecting off the ramp wall on the left cycles approx. 12 frames.

If M11.1 is in fact laying on the floor in pieces (or vaporized - take your pick), I never really can make this comport with the catenary action that is thought to have detached the slab/deck at the building proper and started the load redistribution. You have to accept the idea that the catenary rupture (for lack of a better term) caused it to disintegrate. And this was the column that seems to have only one rebar sticking out of the floor after the sight was cleared. So maybe M11.1 was just for show by the time this progession began at pace. It would have had to been repaired a lot though over time. And that would have been criminal if that were the case.

That, in fact, is a creative theory. Yikes!

I would also call it creative to apply band aid repairs that have been documented to have failed. Failed epoxy injection comes to mind. How far did they go?

I had posted these photos back in September, these were shot during a walkthrough of the collapse site on 9/10/2021. These show pretty close up if you can zoom on them, look at the damage atop the wall and slab connection.

Also, look where the dark brown stripe on the wall meets the slab, you can see very clear detailed damage and the rebar sticking out.

Does the concrete erosion the base of the wall look significantly worse where the generator happens to be sitting? Is water continuing to run in at that spot even after the site was cleaned up?

Well not to say "even after". I think it was a reasonable question to ask how water was entering the basement before the collapse. But I never saw much said about it as they struggled to dewater. Was there a lack of access to observe those details?

Quote (IanCA (Mechanical) 6 Feb 22 17:53)

The linked document is here:

Quote (sgw1009 (Computer) 6 Feb 22 18:36)

...followed by K12.1...

There are two typos in that document. First the depth of soil I used was 18 inches and not 16 inches. Second, column K-12.1 is actually K-11.1. My apologies.

Quote (MaudSTL (Computer) 7 Feb 22 00:50)

...there is a gap of about five minutes between the first crash heard on the first floor at 1:10 (which apparently did not cause noticeable debris in the garage) and the deck collapse at ~1:15...

There is a possible explanation that would not cause noticeable debris in the garage. Suppose that column K-13.1 punched through but the deck but was still suspended between gridlines 12.1/11.1 and 14.1 in the N-S axis and between gridlines I and L in the E-W axis sort of like a circus tent that has lost a pole and the tent is still supported by other poles. It is possible that the deflection may have only been of a foot or two. The garage ceiling was about 12 to 14 feet from the video, but I haven't tried to figure it out from the drawings. If the Vazquezes had parked in the northern part of the garage, they might not have noticed that the ceiling was sagging. That might explain the crash at 1:10 AM followed by the complete collapse of the deck at about 1:15 AM. Just a thought.

EDIT: I ran some numbers based on a one-way slab turning into a catenary cable, which is where I came up with the deflection of 2 feet. It should be calculated as a two-way catenary, but I'm not sure I can do that. I decided not to post my calculations so as not to embarass myself, as I am not a structural engineer.

EDIT 2:

Quote (Sym P. le (Mechanical) 6 Feb 22 23:21)

The lowering of the lobby parking into the garage level may have been graduated by a succession of failures rather than all in one go.

Quote (Sym P. le (Mechanical) 7 Feb 22 03:43)

What I don't see is a full thickness of slab laying on the garage floor.

What happened to the structure in front of KLM-9.1 is a head scratcher. Here are some thoughts. The illustrations may not all fit in one comment, so I may have to post them in follow up comments. First of all, here is the detail for the step beam and "Beam A" (see Figure 1).

Figure 1:


Between K and M along 9.1 the slab drops 7 inches instead of 18 inches. There is a further 11 inch drop between gridline 9.1 and 11.1 between K and M. According to Figure 1, beams type A should have been stair-stepped along KLM between 9.1 and 11.1. However, if you look at Figure 2 (from the garage video), you can see that along M, beam A is NOT stair-stepped. The garage video does not show beam A along K and L very clearly. However, we can surmise that beam A along K was also NOT stair -stepped and that it WAS stair-stepped along L, because the step-beam along gridline 9.1 was shallower between K and M along 9.1. That would have made L-9.1 the weakest column. Apparently not built according to plan. Thus, beam A at column M-9.1 would have had a deeper section that in the drawings and might have been been more resistant to shear. Just a thought.

Figure 2 (three views of column M-9.1):

Here is the detail of the structure in front of KLM-9.1. It is from the original Breiterman drawing s5 of 14 with 1/17/80 revision titled "Lobby Level Framing Plan."

Following the creative juices that just flowed, I will throw this imagination in

How does a 2-way slab become a one way slab, resulting in IEGeezer’s 3-ring Circus Big Top scenario?

If his K column punches first, but grid keeps tent ⛺️ up, that stresses all perimeter connections around the failed interior connection.

We definitely have construction joint N-S on East side of drive, and there is probably another one west of K or at K.

So if a big top center pole punches, then the first sides of tent anchors to move are at the construction joints. Thus creating IEGeezer’s centenary one way slab tension between building and retaining wall???

Some rubble falls from initial load transfer, deck sags but remains up for a while, then drops all at once when each end of remaining perimeter anchor points fail.

This would line up with timeline and explain the lateral movements back and forth prior to collapse.

Like a tug of war, if u will. And of course we now have 4 direction wave action between internal center point punch and perimeter sides??? 🤔

If there is N-S construction joint under K line planters, would that not explain failure spreading east and west between parking and pool decks?

Why not keep digging, while neurons are firing? Ventilation fan exhaust in planter along K-Line, probably not well isolated from planter thus any chemicals dumped in that area spread N-S and E-W from that vent location. Thus we have weak concrete and delamination under large loads and skinny columns.

I am leaning IEGeezer Now! However, thst is subject to change just like the wind. The failure could start at wall under planters and spread quickly North down K line.

Ok let me get this off my mind, since Sym P. le reposted death ☠️ by video processing again. I have always wondered why light shining from South-West side of gate, but dark to East side.

Due to catenary action at building, South wall is actually braced better than IJKl column line or close enough they both loose?

Fresh off the press. 💩

EDIT: Zebraso you are up! 😂

Quote (thermopile)

I have always wondered why light shining from South-West side of gate, but dark to East side.

Sheet E2 shows all parking level driveway lighting is fed from the emergency panel "XA" and normal power for lights in the parking areas come from panel "HA" . Since the lighting panels are located in the North-West corner of the building and the conduits run in the deck that collapsed, resulting in that debris pile, it could have easily taken out all lights on the parking level East and South of the collapse. Because there are some lights still working I would assume the breakers didn't trip but the conduits or wires were pulled apart.

NukeDude,

Thanks for your explanation. I was thinking more along the lines of an opening in the deck allowing light in from SW coupled with your explanation. Or a dangling emergency light from wires pulled out of downstream conduit but still on, as per your explanation.

The angle of light bothers me and other properties about it.

We had a similar discussion about a stereo pair back in https://www.eng-tips.com/viewthread.cfm?qid=485379 part 7 (search for 'stereo').

@Sym P Le - you have posted a slightly different pair but I still don't see anything convincing apart from the concrete box around where M11.1 should be. You can make your eyes see all sorts of things in grainy images but I don't see a car there. As I said back in part 7, the strange thing about this pic is that you can't see M13.1, which we know survived (it was visible after punching through the deck). That means that the fact you also can't see M11.1 isn't conclusive evidence that that column broke or disintegrated.

However I do agree that it doesn't look like there's a full 9' of slab on the floor there. But if that concrete box is a planter from the deck above, there must be, at least behind it. Perhaps there's just more water in the bottom already than we think.

Interesting View of Existing South Perimeter Wall, and what appears to be as-built conditions, contained in the Morabito 40-year certification plans. Note the Deck Slab and a edge beam appear to have been poured on top of wall, thus explaining what looks like a cold joint in the vertical wall.

It appears the capped sheet pile topping was thicker than just the slab thickness.

Here is a PDF file better image of South Wall as-built and repair plan

• https://files.engineering.com/getfile.aspx?folder=b22254a3-6c15-4c76-ae23-8

Morabito plans were replacing 4 exhaust fans in the garage at existing locations. I have noted those locations on linked plan. I don't see anything in 40-Year certification plans about ventilation fan from pool area that exhausted in planter.

• https://files.engineering.com/getfile.aspx?folder=476d6de6-b41c-4ba4-a4eb-1

Quote (thermopile)

I don't see anything in 40-Year certification plans about ventilation fan from pool area that exhausted in planter.

Someplace I read that one parking level exhaust fan had a missing belt and another had a vibration issue. It's nice that Morabito decided to replace them all. The new pool fan is shown on the drawing that you provided and is labeled EF-P1. It is likely fed from the new "pool equipment room panel" as it only feeds one circuit but it isn't labeled at either end. Morabito's electrical drawings are as bad and incomplete as the original 1980 drawings.

Nukedude, Thanks again, I see it now. I totally overlooked the new pool equipment room fan and duct work. Working with these images on a laptop computer is not the best scenario... Yes the mechanical report I read mentioned only replacing belts and bearings on exhaust fans.

Morabito is going to have to fight with his insurer. Engineering Firm Must Face Insurers’ Suit Seeking to Escape Coverage for Surfside Collapse

This reposted picture shows the different failures along South Wall between parking deck and patio deck from a different perspective. K-line being the dividing line between different phases of failure. Coupled with last image in IanCA's 6 Feb 22 06:30 post above:

Here is the deleted post in which the poster has withheld their name.

--------------------------------------------------------------------------------------------------------------------------------------------------------------
Current Post: Edited 08 Feb 22 12:35
Original Post: Posted 08 Feb 22 12:26
Nothing to see here. I just thought I'd check in to see how this thread was progressing. I was curious. I had nothing better to do so I did a quick review of the number of posts for the time period Feb 1-7. I didn't read any of them (who has the patience at this point), just added them up. Here are the results:

0.14 posts/day - NukeDude948, sgw1009, AusTony2046, spsalso, AutisticBez
0.29 posts/day - Reverse_Bias, AusG, SwinnyGG
0.43 posts/day - Jeff Ostroff
0.57 posts/day - Red Corona
0.71 posts/day - Lionel Hutz
1.00 posts/day - Optical98
1.29 posts/day - IEGeezer, Zebraso
1.86 posts/day - MaudSTL
3.71 posts/day - Sym P.Ie
4.00 posts/day - IanCA
5.86 posts/day - Thermopile

For a total of 139 posts/week => Extrapolating out to 7,228 posts/year

It's interesting--well, really not that interesting--but the two most prolific posters are names that are new to me. But are these really new people, or just the same ISP web address, but with a different user name? Who knows what the policy is for engineering.com.

--------------------------------------------------------------------------------------------------------------------------------------------------------------

I for one, who love to sit and listen to a limited invite presentation from IanCA, IEGeezer and others on their theories as they have introduced some interesting thoughts and evidence evaluation, IMO. e.g. The re-posted image below with narrative. I think IanCA and IEGeezer have the most interesting theories going currently, based upon limited public evidence, and Sym P. le is a great rock thrower to force critical thinking and evaluation and discussion. However all theories must be considered at first and then go throw a manageable and creditable amount of rock to narrow candidates down for the SuperBowl Half Time Show.



Nuke.........948, I am editing this post to tell you that your earned a Star for your post directly after this one. I have used my one Post allotment Per Month today, so I will have to edit this post, because we are being watched by the ..............!

Anything you post, can and will be used against you in a court of law...

Ahem...only "prolific" posts. Oh, wait where have I heard that term?

Suddenly, when I click on the lawyer's "member profile", all I get is an error message.
Nice name change.

Quote (mystery)

I didn't read any of them

Yeah, no.

Have we lost our ‘Rock Chucker’ since his name was recognized by ‘Mystery’ Poster, and he was associated with the likes of the folks on ‘Mystery’s’ Black List?

Edit:! Perhaps we need to call in the ‘Nuke’

Seriously, it is sad that the new analysis and piecing together of the long available evidence puzzle pieces 🧩 was making progress, until a ‘Mystery’ poster with an counter agenda, has shut down the collaboration.

Clearly a public forum is great for gathering the pieces to the puzzle, but probably the ‘Worst’ place for intellectual discussions of candidate theories and evidence to take place.

So I guess we wait for the massive coverup to extrude the special interest message so far down the road, average folks don’t realize they been screwed again by the power brokers.

Edit: This is a multi-discipline system problem requiring experts from many broad backgrounds and expertise to get as close as possible to likely trigger initiating event and subsequent order of theoretical progressions.

Thermo

No reason to stop the convo, please proceed. I'm not concerned about the 'mystery' posters, merely amused...
as I'm sure the other 5 posters on this thread are.

Optical, thanks for even suggesting my input matters. What is needed is for IanCA to finish laying out his analysis 🧐, and IEGeezer. I have just been trying to follow their concepts and ask questions, out loud, to help understand their evaluations of available evidence. One problem on a forum like this is, we all bring tools to table but because it takes an understanding of multi-disciplines, we all grasp different concepts at a different pace. That is, say I ask a dumb electrical question, that is just raising the noise floor to the problem at hand, and causing a lot of back and forth for people to understand concepts outside their wheel house.

Which scenario of Sym P.'s case 1,2, or 3, makes it more likely that the inner planter wall in zone A falls substantially below the level of the visible stampcrete along the tension crack line. Is there any case where you would expect to see the planter wall lying over on top of the visible stampcrete or wedged against it?

Zebraso, I am thinking the diagonal movement in Zone 2, and break up of planter between 1 and 2 indicate movement or failure at or west of K-line first. Zone 3 and beyond where deck at south wall is draped, tells me the wall won there and pulled building columns South.

Also, with wall winning Zone 3 and east, would explain missing column early in garage video

Are you saying there was rotational torque on the "missing" column?

Does that explain all rebar sheared of but one?

Sorry typo above. Replaced deck with south wall winning. I think IEGeezer’s one way slab idea makes since. Perhaps some rotational torque on The missing M11.1 deck column from weak deck attachment,at South to North construction joint on East side, letting go to create one way slab with catenary tension tug of war between missing M11.1 column and L11.1 and South wall.

Can anything about the amount of diagonal movement be inferred here:


Ok the idea I'm reaching for is that there could have been a large horizontal moment about a vertical center in the area of the step beam if the large area of the pool deck moves west even slightly. Obviously the columns that punched are more or less vertical but I don't think that means a significant horizontal moment did not exist.

What I find interesting in the red-circled area is that there is so little damage to the column. The pavers tilted up as the deck fell down. You could almost just fold them back, and get back to normal.

Y'all might want to integrate that into your views of horizontal movements of the deck.

How is it that the deck dropped down that column like it was lubricated by KY Jelly?

I am sure NIST will reveal all, at some later time.



spsalso

stampcrete held together better than the deck parking deck? KY? It's the basement parking so maybe. Too much KY. Must be the transients.

Edit: I find it improbable that the folded up stampcrete rolled or fell over the top bar and landed in that position. So I am rejecting any conclusions based on where it appears in these photos. IOW I think it was moved. I'm not drawing anything nefarious but I don't see any other way than someone did not like it where they found it. Maybe the hole there was a safety issue.

Quote (Sym P. le)

6 Feb 22 22:18
Because the planter is continually supported by the wall and has no ability to impart significant bending moments to the slab.

Do you think it is possible that, over time, several of the vertical bars in the wall failed, the concrete failed, sheared, horizontally and zone A was, or portions of it were, resting on the top of the wall without being physically connected?

Quote (Sym P. le)

I need a lot more help before I believe the corrosion driving the collapse theory. (Edit: along the south perimeter wall)

@Sym P. le, thanks for leaving the door open. I'll keep working on it, step by step, with backup.

Quote (spsalso (Electrical))

How is it that the deck dropped down that column like it was lubricated by KY Jelly?

I should have responded directly instead of editing my prior post. That was wrong, sorry.

You are correct. Nothing slid against that column. That's not the nature of the the punch shear the way these punched. That was pointed out. This was abnormal. I have to go back pretty far to find that explanation. But beyond that the stampcrete popped off because the adhesion was not all that great. And that did not scrape the column either because the rebar pushed it away. So that's why it seems inexplicable that it is found in a position as if it did scrape the column as if it slid down. So no KY is needed. It's easy to forget the reason these punched so easily.

Quote (thermopyle2.1)

I did some reading up on pool chemicals, and how they control the pH and the chemical effects on concrete from the Portland Cement Association.

@thermopyle2.1
Sorry that it took me a while to get back to posting here.
Thanks very much for that helpful document. I believe the sections below are particularly relevant and I have added emphasis.

Chlorides dissolved in water can permeate through sound concrete or reach the steel through cracks. Chloride-containing admixtures can also cause corrosion. No other contaminant is documented as extensively in the literature as a cause of corrosion of metals in concrete than chloride ions. The mechanism by which chlorides promote corrosion is not entirely understood, but the most popular theory is that chloride ions penetrate the protective oxide film easier than do other ions, leaving the steel vulnerable to corrosion. The risk of corrosion increases as the chloride content of concrete increases

The important point for me about the cracks is that we know the waterproofing in the planters had failed, we know the parking deck did not have waterproofing, had cracks, had been repaired unsuccessfully in the past and we can see that the wall-deck connection in zone A had cracked horizontally. As a result, there was a path for liquid from the planters into the structure, into the concrete, and into contact with the steel.

ACI 318 chloride limit history

After much debate, a table showing maximum chloride ion contents for different types of concrete members first appeared 15 years ago in ACI 318-83,

When Champlain Towers South was built chloride ion content in concrete was uncontrolled. The cost of aggregate is closely related to haulage distance: aggregate cost. Aggregate from coastal regions has the potential for higher chloride ion levels. The area of the southern wall adjacent to the parking deck at CTS had two additional sources of chloride ions, including the exhaust from the pool equipment room.

The primary rate-controlling factors are the availability of oxygen, the electrical resistivity and relative humidity of the concrete, and the pH and temperature.

We know the garage area was designed with several fans to try and control humidity, that airflow meant the oxygen level was normal, the electrical resistivity would be relatively low, the irrigation runoff from the planters meant that the humidity of the concrete was high, but also variable, which is known to be worse than constantly high humidity, I will come back to pH in the future, and the ambient temperature is high. All bad conditions for increasing the rate of corrosion.

If the deck collapse started at the wall on the southern end of the deck and then progressed northward toward the building, then why don’t we see the collapsed deck in the TikTok photos posted by Sym P. le above? These photos appear to show sprinkler pipes and drainage pipes that were hanging from the garage ceiling underneath the deck, but no trace of the deck itself. Could the deck have not fallen yet in these photos?

"When Champlain Towers South was built chloride ion content in concrete was uncontrolled."

Really?

Then it was accepted to use salt water in concrete mixing in 1980? THAT would be pretty uncontrolled. And provide LOTS of chloride.


spsalso

Quote (MarkBoB2)

…why don’t we see the collapsed deck in the TikTok photos…

Here’s the perspective of the TT video. There wasn’t enough light to see beyond the rubble to the collapsed deck outside of the building. From the Miami Herald House of Cards infographic:

Quote (spsalso)

Feb 22 04:49
"When Champlain Towers South was built chloride ion content in concrete was uncontrolled."

Really?

Okay, I admit I was winging it a bit in that post due to time constraints. Perhaps "unregulated" would be a better phrase. But I have since found more good supporting evidence:
Evaluation-of-Chloride-Limits.pdf

"Chloride ions present in deicing chemicals and seawater are the primary source of external chlorides that can migrate to the reinforcing steel in concrete to cause corrosion of steel in concrete." I believe we need to add a third source.

"The current ACI 318 Building Code chloride limits are based on research in the 1980s with primarily portland cement mixtures."

Literature Review of Chloride Threshold Values for Grouted Post-Tensioned Tendons
This document, on page 6, shows research was being done on chloride concentration in concrete as early as 1975

"The first comprehensive literature review of chloride threshold values was done during efforts to investigate the most accurate way of representing chloride threshold values.(18) Among 20 chloride threshold values reported by Glass and Buenfeld
Glass, G.K. and Buenfeld, N.R. (1997). They concluded that total chloride content relative to weight of cement is best for expressing a chloride threshold value"

"The investigators were able to confirm that tendon failure by strand corrosion can be realized in as little as 7 years"

"If the strands were embedded completely in grout, both unstressed and stressed strands experienced similar capacity reductions. If they were exposed in the voids, the stressed strands experienced much higher capacity losses (more corrosion damage) than the unstressed counterparts. The largest mean capacity reduction was observed when the stressed strands intersected the voids perpendicularly in grout that was exposed to 0.006 and 1.8 percent chloride ions. The researchers concluded that it is important to protect the ducts and strands from water and chlorides and also to eliminate grout voids to prevent or minimize the strand capacity reduction. According to their reliability model, a PT bridge can fail as early as 21 years after construction if the strands are subjected to high-chloride environments. "

Also of interest:
Determination of Chloride Content in Cementitious Materials:

Quote (MarkBoB2)

11 Feb 22 00:54
If the deck collapse started at the wall on the southern end of the deck and then progressed northward toward the building, then why don’t we see the collapsed deck in the TikTok photos posted by Sym P. le above?

@MarkBob2, I think it is possible that the north side of the deck was still supported, attached, or partially attached to the columns and drop slab that ran east-west along the south side of the portion of the building that collapsed (at row 9.1/10). Or even that some columns along 11.1 had not yet punched through. I can imagine parts of the weaker planters breaking away and dropping through the deck while stronger areas, where beams were present, remained intact for a few minutes.

Regardless, I'm sure it got into the 40 year old structure of the pool deck, one way or another.

Quote (Then it was accepted to use salt water in concrete mixing in 1980?)

Chlorides and corrosion have been know to be a problem since the early 70s.

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

-Dik

This article:

Link

says:

"Chloride ions can penetrate into the concrete and cause accelerated corrosion of the reinforcement. The chemical reaction of the cement paste with the high-chloride content of seawater is generally slight and not a primary cause of concern."

This would seem to mean that if chlorides got into the pool deck, it would show up as corrosion of the rebar, and not affect the concrete.

So, while the concrete of the pool deck would not be affected, there should be some nasty looking rebar showing.

Where is it?


spsalso

This makes me question the latest concrete repair. IMHO, both the concrete strength and the concrete cover was way too low.

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

-Dik

Quote (spsalso (Electrical))

The chemical reaction of the cement paste with the high-chloride content of seawater is generally slight

That statement might rely very heavily on the context of time. Or it just might be wrong. Sodium is very reactive with many elements. ferrous metals are not the only thing that are subject to corrosion from what I understand. Acidic reactions will break down the cured concrete paste most assuredly. And I believe (not totally sure) that sodium chloride creates a mildly acidic pH in the concrete pores. I mean how do we expect the chloride to get to the steel if the concrete is impervious aside from the odd crack that forms? That can't be the mechanism that is most worrisome or the only one. Where are the chemical engineers on this website?

Chlorides reduce the passivity of the high pH of concrete and greatly enhances corrosion of the rebar. Check the link:

https://www.engineeringenotes.com/concrete-technol...

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

-Dik

Quote (Sodium is very reactive with many elements.)

It's the high pH that provides the passivity to prevent reinforcing degradation... the chlorides reduce this protection.

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

-Dik

Someone might want to start Part 16...

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

-Dik

sulphates in concrete create acidic compounds also with moisture. aluminum content forms crystals that expand and cause cracks etc. I have to agree with your statement that the original quality and cover of the concrete means a lot. And we have not heard whether they used beach sand or not.

and that's why they have Type 5 or Type 50 or Type HS (in Canada) concrete... two different critters, here and quite unrelated. Our clays in the Winnipeg area are high sulphate, but this can be overcome. They will still suffer from corrosion issues in chloride environments. The fact that the engineer did not address concrete strength and cover leads me to be a little curious about his qualifications.

catch the link:

https://www.understanding-cement.com/sulfate.html

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

-Dik

Well I think we heard the cores were "curious". Amazing.

"curious" and a couple of bucks will get you a cup of coffee, in these environs.

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

-Dik

Yeah, I thought curious is where you start, not finish. So nobody gets cream and sugar with their coffee.

And yet no one has pointed out examples of badly corroded rebar, yet.

I'm not saying it didn't happen. But show me!



spsalso

Quote (spsalso)

And yet no one has pointed out examples of badly corroded rebar, yet.

I'm not saying it didn't happen. But show me!

Also, at 24 seconds in the Fiorella Terenzi CTS garage walk-through video, that looks like iron oxide in the runoff on the ceiling to me.

Garage walkthrough video

And there is zero zippering in that photo. That steel didn't shear so much as crumble. and what accounts for the color of that concrete,err.... what contaminant? Let's conjecture.

Edit: That discoloration could be a long standing crack that had been infiltrated by materials.

What size are those rebars supposed to be? If the pavers below are 4" wide, the broken rebar above them must be no more than .25" diameter.

Quote (dik (Structural)12 Feb 22 03:17)

https://www.understanding-cement.com/sulfate.html

Interesting part of dlk's link to understanding-cement and sulfates and the internal and external attacks, is the following quote from the link: "Alteration of paste composition, with monosulfate phase converting to ettringite and, in later stages, gypsum formation."

The 'curious' concrete in the core samples and showing at the South wall for example sure looks like it has chemically changed and that describing the powdery white mix as gypsum formation sure seems to fit what I am seeing in the pictures.

The link goes on to say this results in loss of strength in concrete and salt water environments can result in this types reactions.

Definitely a good link to read about all concrete changing over time, thus resulting in loss of concrete strength with or without rebar corrosion.

In the walk-through video mentioned above, I see:

a probably rusty thing hanging from the ceiling
several brownish hanging things
all of the above on a diagonal line, which is unlikely to be following the layout of rebar


In the picture with the five red circles, I see holes. Not rebar. I don't see any rusty discoloration around the holes.


Show me the rust-damaged rebar. Not rusty colored, by the way, but damaged enough to have been contributory to the collapse.

I am NOT saying there isn't such rebar. Odd, though, that evidence of it is so minimal.



Regarding the crumbly concrete: I don't doubt it. The explosives guy mentioned seeing it when he placed his charges. One could wonder how that came to be.


spsalso

Quote (spsalso)

several brownish hanging things

calcium deposits leached from the concrete infused with rust from the rebar

Quote (spsalso)

all of the above on a diagonal line, which is unlikely to be following the layout of rebar

following the path of the documented cracks.

Quote (spsalso)

In the picture with the five red circles, I see holes. Not rebar. I don't see any rusty discoloration around the holes.

Please suggest the approximate tensile strength of them holes.

Quote (spsalso)

Show me the rust-damaged rebar. Not rusty colored, by the way, but damaged enough to have been contributory to the collapse.
I am NOT saying there isn't such rebar. Odd, though, that evidence of it is so minimal.

Nope. Not good enough. You'll need to get a LOT closer shot of those 4 bars to show the rust damage.


I do like the graphic on the left in the photo. Gee, did someone "forget" some rebar?


spsalso

So if spalling concrete due to suspected rebar corrosion does not show external stains or exposed rusty rebar then we don't believe there is corroded rebar. Question: does all corroded rebar cause spalling or can it be contained if it is deep enough?

Quote (thermopyle2.1 (Military))

thus resulting in loss of concrete strength with or without rebar corrosion

How do we explain that efflorescence can damage structural concrete elements without rebar in the equation if that were not true?

Quote (spsalso)

You'll need to get a LOT closer shot of those 4 bars to show the rust damage.

I will work on getting that for you. An important point to keep in mind here is that the bars within the slab are critical because if they fail in two different north-south locations (e.g. 4 feet and 9 feet from the wall, as indicated in my post on 3 Feb 22 06:07) that allows the deck to retract from the wall. But those locations were buried under debris and photographic evidence is not readily available, for several reasons.

About the 5 red circles photo. Could the brownish (dare I say orange) stains be the outflux of iron oxide via a long standing crack that would also have left moisture access to steel? The iron oxide has to go somewhere.

@dlk & @thermopyle2.1
Thanks for the link related to sulfates, that's interesting. I see it mentions seawater as a potential source.

Quote (zebraso)

does all corroded rebar cause spalling

I can imagine two conditions where it may not. The first is when the corrosion is occurring on rebar exposed due to a crack in the concrete. Expansion of the rust into the crack may not cause spalling, but if the rebar is highly stressed at that location it would surely increase the chances of stress corrosion cracking. The second is when the rust becomes fluid and can migrate away from the corrosion site.

Quote (AusTony2046)

What size are those rebars supposed to be? If the pavers below are 4" wide, the broken rebar above them must be no more than .25" diameter.

The 9.5" deck measures 97 pixels, the bar/hole measures 6 pixels, making the bar/hole 0.58". The bricks are 4" wide, because the tiles are 12", same as the Home Depot buckets seen in other shots. The bricks measure 35 pixels making the bar 0.69". The bar was intended to be #5 (0.625") so it's pretty close.

Quote (IanCA (Mechanical))

I can imagine two conditions where it may not.

Thank you. By fluid I guess it means suspended on liquid. I guess part of the equation is determining whether the crack has the capacity to carry away the iron oxide and there is enough liquid flow to make that happen. Any reason to believe there was insufficient liquid on top of these decks? It's not that simple. I know.

Looking at core samples we see where concrete appears to have delaminated with minimal looking rebar corrosion, and where outer layer of concrete looks like it has chemically changed to a white powdery substance, while the layer on inner side of delamination still looks more like concrete. From dlk’s links, it sounds like sulfates can migrate into concrete and creating layers as it progresses from external inward.

These two posts are helpful in relation to the discussion on chloride ions and corrosion:

Quote (davefitz)

5 Jul 21 04:36
Reviewed a little history of the use of modern admixtures in concrete to reduce its permeability to chloride ions, and it seems that the modern use of super plasticizer was not common in the USA circa 1980 when this condo was built. Reducing the water/cement ratio to below 0.4 and adding fine pozzalans is used today to reduce the diffusion rate of chloride ions to the rebar, and the plasticizer aids in reducing the water to cement ratio. If the workability was not enhanced by using plasticizer, is it possible they added calcium chloride to improve workability but compromised rebar life?

Quote (dik)

5 Jul 21 04:56
I figured the w/c would be between 0.4 and 0.45. With RJC and the parking garage experience they had, we were typically using 4.5 to 5.0 ksi stuff back then for parkade slabs and 1-1/2" min cover for slabs and 2-1/2" for columns as well as 4" slump was common... substantially higher than most consultants at the time. This was not for a marine salt environment... put typical de-icer salts.

Quote (dik)

12 Feb 22 02:49
This makes me question the latest concrete repair. IMHO, both the concrete strength and the concrete cover was way too low.

I completely agree, the coverage specified for CTS certainly appears less than adequate for the environment and doesn't align with current best practices. For example, Mirabato drawing .C2C-1.1 from 8777-collins-avenue---preliminary-review-plans-for-40-year-re-certification.pdf calls for only "3/4" MINIMUM COVER FOR SLABS"

Which is at odds with these documents:
Link recommends 2.5 inches of cover for marine exposure.
Link recommends 50mm for marine concrete.
ACI 318-14 table 20.6.1.3.1 requires 1 1/2" minimum cover for #5 or smaller bars exposed to the weather in all members.

Even ACI 318-14 seems inadequate to ensure that concrete used in marine environments has sufficient coverage. Corrosion Protection of reinforcement class C2 is defined as concrete exposed to moisture and an external source of chlorides from ... seawater or spray from these sources. Table 19.3.2.1 addresses the requirements for concrete by exposure class and specifies the maximum water to cementitious material ratio (w/cm) of 0.4, minimum compressive strength of 5000 psi, maximum chloride ion content %/wt 0.15 with the additional provision of concrete cover in accordance with 20.6. But section 20.6 does not contain any marine, salt, or chloride ion-related adjustments.
The commentary states: Conditions should be evaluated for structures exposed to chlorides, such as in parking structures where chlorides may be tracked in by vehicles, or in structures near seawater

The collapse of CTS gives us a very good reason to evaluate the conditions in marine environments and to consider increasing and clearly stating, the minimum coverage requirements under those conditions.

Quote (it sounds like sulfates can migrate into concrete and creating layers as it progresses from external inward.)

They are two distinctly different problems. Chloride deterioration can occur in addition to sulphate attack. De-icer salts and a marine environment are similar, but two distinctly different environments. I've had very limited exposure to marine environments, but I'd know where to look...

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

-Dik

Quote (How do we explain that efflorescence can damage structural concrete elements without rebar in the equation if that were not true?)

There's a process called crypto efflorescence, where soluble salt crystals expand and cause distress to the concrete. The expansion causes the concrete to fail. When this fails, it puts stress on the reinforcing. You should start Part 16, this thread is getting too long.

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

-Dik

I see now that the process where the salt is migrated into the pores from external sources is also called "secondary efflorescence".
I also see this interesting quote from the wikipedia article on efflorescence: "Virtual stalactites can be formed in some cases as a result of dissolved cement stone, hanging off cracks in concrete structures. Where this process has taken hold, the structural integrity of a concrete element is at risk. This is a common traffic infrastructure and building maintenance concern. Secondary efflorescence is akin to osteoporosis of the concrete" italics added by me. So what repair or remediation addresses osteoporosis of concrete? Anything short of replacement?

Also to add: were the cores from the parking deck supposed to be tested to destruction with a load cell?

Time to move this on to Part 16

thread815-491934: Miami Beach, Champlain Towers South apartment building collapse, Part 16

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

-Dik

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