Miami Beach, Champlain Towers South apartment building collapse, Part 07 90

[Seppe]

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Previous thread (Part 06)
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https://www.eng-tips.com/viewthread.cfm?qid=485223

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[spinspecdrt]

[quote
From the photos of the garage provided by a prospective buyer,][/quote]

I can imagine the conversation.

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

 

[Vance Wiley]

Thank you. Not such a great beam -
And thank you, Mike.

 

[SFCharlie]

Senator Jason Pizzo's Twitter

Thanks!

SF Charlie
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[Colostruct]

SFCharlie

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

 

[rodface]

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

 

[SFCharlie]

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

Here are two higher quality outtakes from that video

SF Charlie
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[SFCharlie]

Screen shot #2

SF Charlie
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[AutisticBez]

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

 

[Murph 9000]

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

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

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

 

[Cool_Controls]

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

 

[AusG]

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

 

[Sym P. le]

This

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

 

[Penagwin]

There was a release of permits for their repairs [URL unfurl="true"]https://surfside.one/public-records-search/[/url]

 

[gonefishing2]

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

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

 

[Eufalconimorph]

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

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

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

 

[Demented]

@thermopile
Going to give it a listen now.

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

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

Very common practice here.

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

 

[microwizard]

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

Exponential means a doubling in a fixed time period, the period could be a second, a year, or a decade. Since the report does not specify a time period, nothing can be inferred from that statement about any timing involved.

Now if the engineer had said "the building will catastrophically collapse within 5 years" then that might be different, but there was no way he could know that, and I don't think he would even predict.

We need to be beware of Outcome bias. The interesting thing is that symptoms shown at CTS were not particularly severe, nor showing imminent collapse - *assuming* that the building was built to spec.

It makes me wonder, how often does it happen that a building inspection determines that a collapse is imminent (i.e. within a month), and the building subsequently collapses of it's own accord?

 

[gonefishing2]

Still many factors in play, just the layer theory sure provides some good rationale to sudden collapse after a number of years.... and just needing a nudge at the right moment to set progressive things in motion. It would appear the interior slabs at exterior balcony slabs in area of IKLM 9.1 could have been weaken from moisture intrusion or now perhaps layering of those slabs too??

Layering could explain the shaking of building too.....

 

[gonefishing2]

So I would argue the signs were there, but perhaps training and codes have not caught up with this risk? Actual construction methods is on the Contractors. But sure would be interesting to know who gave approval to layering of structural slab and how often that occurs?

 

[Demented]

@Thermipile

I really need to give a watch not a listen it seems.


However my take on water accumulation leading to it? In my honest opinion, it only enforces it, but in no considerable way. It only raises more questions and possibilities that need to be investigated. From the beginning I stated how I feared water may have been pooling and collecting in between the layers, and upon failure, thats what we saw leaking in the tiktok video.


I might not have mentioned it as I felt it were not likely or possible, but water hydraulicing between the slabs could have led to shifting.

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