Miami Beach, Champlain Towers South apartment building collapse, Part 16 24

[dik]

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

-Dik

 

[zebraso]

Can the deck droop at south wall and the release of tension be separated. Let's say it drooped. Does it necessarily follow that it altered the diaphragm action in significant any way that led to an inevitable collapse. This might seem heretical. But there it is.

 

[Sym P. le]

you missed the last part of the sentence. The tie-in is not intended to anchor a tightrope.


no

 

[SFCharlie]

The tie-in is not intended to anchor a tightrope.

So, where does the tension of the deck catenary supposedly go?

SF Charlie
Eng-Tips.com Forum Policies

 

[Sym P. le]

This is not a tightrope, at least if its functioning as intended. A stiff slab will sit on its support and sag slightly, imparting a slight bending moment to the support if tied in, or toeing up slightly and pushing out on the support if not tied in. It's only when interior column supports fail that the functional aspect changes to the extent that it acts like a tightrope requiring tensile forces to be resolved with further design implications.

As far as my no answer, there is no such thing as drooping at the south support so it's a nonstarter.

 

[zebraso]

Well then my question is overly convoluted to begin with. I thought it might be. There is such a thing as a bad question.

Add: incorrect premise. The assumption has to be the tie-ins broke after the collapse initiated. I am struggling to see a way around that.

Add more: It might help me in my mind to say there is not tightrope the spans the length of multiple columns. I mean I think at this point that is as ridiculous as can be. And then to say the deck between two columns is like a tightrope in two way flat slab? Seriously. What planet are we on?

 

[Sym P. le]

By my account anyway but I've been wrong before.

 

[zebraso]

It seems to me that if you throw out the principle of how two way flat slab works to explain how it failed then the explanation has already failed before it begins. And I imagine how that goes is: well it's in such a state that it no longer resembles flat slab and let's start from there. Well then the part about what caused it has been skipped over in order to explain it. I don't know though. It's just what it seems like to me. Somehow the long standing state of gradual decay supposedly changes the rules and it has morphed into a 7 headed beast? I feel like maybe Occum is knocking.

I'm not trying to put a damper on anything. Carry on.

 

[FJBnomics]

And area that appeared to drop into sink hole was a low spot, based upon drain locations and survey, and over loaded more.

The cropped image below, IMO shows movement towards the sink hole.

Edit: Actually rotation of planter wall may be more of the opposite effect, or indication of movement West at South wall end.

 

[zebraso]

I'm thinking about attempts at remediation. Clearly it was established there were multiple problems with the pool deck for a long time prior to the collapse. There were stalactites from secondary efflorescence. There were catch pans under the deck. There was spalling and cracks. The basement flooded. They injected epoxy, and tried to water proof the deck with a membrane and slope it to manage water better. These things failed. I just think that focusing on why and how they failed might be instructive. Was there a problem with the conception or implementation of the remediation? Conceivably if these things had succeeded in addressing the problems they actually saw, they would not have still needed catch pans under the deck in july 2020 and had water streaming down 76 in Nov 2020. Finally did the remediation actually make things worse?

 

[FJBnomics]

Designed and built to fail in 15 years, and bondo’d to hide the defects

 

[zebraso]

Both aspects of that statements are worth evaluating. Maybe they were not outright intentions. Standards change, and things were done in error also. Bondo vs epoxy. Yeah you are probably right in some sense. If it was really 15 years in hindsight they did one hell of a job. I don't want to believe that though. IMHO if they would have fixed the deck it should have made it another 40+. Assuming no one set a sail boat on the roof . What is the most evident difference between the construction of the North Towers pool deck and the South?

 

[FJBnomics]

Reminds me of lead acid batteries designed to fail sooner than warranty period, to hook you into taking your $3 credit towards a new battery from same mfg/retailer, rather than punting them and buying another brand.

 

[zebraso]

Well that's a scheme on something that's more or less a consumable. I don't know if that is cheating per se. Designed obsolescence is a real thing. But I can't think that anything in the construction of a mid-rise applies quite that way. When you cheat there it is a major crime. Radio Shack batteries were crap too and they got you back with the battery of the month club. But you accepted they were crap.

 

[IanCA]

Perhaps there is way more than 5% BOTS in what is published?

On the subject of action figures, I do apologize to everyone who has contributed to this thread for my Feb 13 attempt at transformer humor and I very much appreciated the correct and humorous response from Nukeman948. I had searched for hours to find that product image (with the knockouts in the correct position) without success. I eventually became embarrassed about seeing the associated image I had posted so I flagged it myself and it was quickly removed.

Suggestions welcome.​

 

[IanCA]

It appears to be in this photo.

Absolutely. The elevation survey shows a change of 3.36 inches (10.22-9.94) between two adjacent points close to the jacuzzi and the wall.

Suggestions welcome.​

 

[IanCA]

Morabito's idea of an edge beam would seem to be wishful thinking.

Agreed, and it doesn't acknowledge the presence of the sheet pile, which introduces discontinuities. The concrete is not bonded to the sheet pile in any way. Is it?

 

[IanCA]

Actually, it is better to throw out their model. MH can update their model to help folks understand how this building fell down and why theirs won't.

Structural Madness's model, though also imperfect, lends better insight to this collapse.

It appears to me that both models have significant deficiencies.

For me the most important criteria for both the Miami Herald and Structural Madness models are:
1) Are they based on reasonably accurate initial conditions?
2) Can they be developed in time, as the collapse of the deck progresses, to produce a similar arrangement of debris at the end?

The problems I see are:
a) Neither model appears to make provision for the construction joints that we know played a critical role in limiting the area of deck collapse and also played an important role in the geometry of the deck after the collapse. For example, the linear depression that runs East-West through the pool deck gate.
b) Neither model appears to include the 19"x19" penetration through the deck that was formed to allow exhaust from the pool equipment room to be vented at the corner of the pool deck.
c) The Structural madness model does not make any allowance for corrosion of the steel or degradation of the concrete and we know they are both critical factors in the collapse.
d) Neither model appears to include any provision for as-built, or as-repaired, conditions of the deck at the Southern edge, as shown below:

Credit to Construction Engineering and Failure Analysis for originally posting that clip.

e) Neither model explains why there would be a dramatic discontinuity in the deck between the pool equipment room exhaust vent and the gate. The area identified by thermobaric in the image above.

area that appeared to drop into sink hole

 

[MaudSTL]

@IanCA, I recently re-watched Jinal’s video of early August, 2021, and IIRC he verbally albeit briefly touches most of the contributing factors on your list, including some construction joints, corrosion, concrete, and maintenance failures…but not the deck penetration. It would be great to see a follow-up from Jinal to look in greater depth at contributing factors.

The MH model is, in my view, more take-it-or-leave-it. Having a background in theatre (rigging) and outside-plant telephone engineering (pole setting and guying,) I am skeptical of the tightrope and compression theories for the south wall and don’t put Jinal’s failure model in the same class as the Miami Herald’s. Plus Occam’s Razor.

 

[FJBnomics]

IanCA, In no way was my >5% BOT analogy in published information related to your transformer post. Since you took it that way, I deleted that post.

When I duck go’d - ‘BOTS’, the Green BOT was 2nd imagine displayed, so I used it.

Edit: Rather my post was referring to disinformation, destruction of evidence and cover up of evidence.

Since IanCA, posted the image of the exposed top of sheet piles in area of interest, I have gone and watched some of Construction Engineering & Failure Analysis’s latest videos.

First a warning , prepare a stiff drink to assist in the painful experience of listening to this guy think out loud in real time, and ramble and ramble to drag things out.

The reward is, you will see images I have not seen before, and receive data you have not seen or heard before.

Filtering thru the noise, is a lot of information not being released by ‘The Ministry of Truth’.

Like evidence of control joint E-W along I14, and crack pictures, and discussion of problem with columns being offset from straight line and the possible effects of that.

We are missing so much information that is being shared to this guy, that leads you down a better understanding of what may have happened.

Edit: No Pain - No Gain

Edit: Have run into some of his videos that say they are private, so I login to youtube and then it tells me they are unavailable. So information is being concealed, by youtube, for some reason, as author claims it is not him doing it.

 

[IanCA]

It would be great to see a follow-up from Jinal to look in greater depth at contributing factors.

I completely agree.

What I would also like to see is his analysis developed past the point where the column which he identifies as the weakest, punches through the deck. In which sequence do the remaining deck support columns punch through? Does the collapse progress to the Southern wall? Does it result in the dramatically different final conditions we see at the wall East and West of column line K? If not, modify the initial conditions and repeat the analysis from the beginning.