Miami Beach, Champlain Towers South apartment building collapse, Part 12 60

[SFCharlie]

A continuation of our discussion of this failure. Best to read the other threads first to avoid rehashing things already discussed.
Miami Beach, Champlain Towers South apartment building collapse
Miami Beach, Champlain Towers South apartment building collapse, Part 02
Miami Beach, Champlain Towers South apartment building collapse, Part 03
Miami Beach, Champlain Towers South apartment building collapse, Part 04
Miami Beach, Champlain Towers South apartment building collapse, Part 05
Miami Beach, Champlain Towers South apartment building collapse, Part 06
Miami Beach, Champlain Towers South apartment building collapse, Part 07
Miami Beach, Champlain Towers South apartment building collapse, Part 08
Miami Beach, Champlain Towers South apartment building collapse, Part 09
Miami Beach, Champlain Towers South apartment building collapse, Part 10
Miami Beach, Champlain Towers South apartment building collapse, Part 11

SF Charlie
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[gonefishing2]

Quote (

https://twitter.com/ICELibrary/status/143297765443...)

Progressive Collapse and #Structural Health Monitoring (SHM) Collection
In response to collapse of Champlain Towers South in Florida, ASCE Library assembled papers highlighting importance of condition assessment of existing buildings. Free until 15 Sept.

https://ascelibrary.org/SHMcollection

The interesting one is about flat slab structures - like CTS.
It has been downloaded over 1800 times. It is either 13 or 18 pages.
@Charlie - It could be a good thing to have all these in the library for this forum - while they are free.
Now there is the beginning of a code to guide(?) the investigation of building disasters.
Kudos to ASCE.

Very Interesting! Attached is the paper "Resistance of Flat-Plate Buildings against Progressive Collapse. I: Modeling of Slab-Column Connections"

I am sure the other papers are equally interesting too. I would say this one is a must read as far as CTS and RC flat slabs prior to 1989 code changes....

 

[Vance Wiley]

Yes - and for the experts performing inspections and recommending repairs.
I aam sure the attack attorneys will ask if the engineer followed these practices should they get involved.

 

[MaudSTL]

The horse-trading begins.

“The fact that Surfside may be culpable and have liability from a negligence standpoint and I hate to say it, even criminal negligence would do anything except try to work with us side by side with us owners to increase the value. Every dollar counts in this situation,” said Oren Cytrynbaum, a self-employed real estate investor, who was a resident of Champlain Towers South.

$49 Million To Be Split Amongst Surfside Victims, Families; Hearing Held To Discuss Future Of Condo Collapse Site

 

[SFCharlie]

At what point does someone need to step in and say that you can't treat a slab like "my grandfather's axe: I've replaced the head twice and the handle three times"?

Your right
After what we know about the structural slab delaminating at the top reinforcement, I think that the only real fix would be to replace the entire slab? But your question about who makes that call, is a valid question.


SF Charlie
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[SFCharlie]

@Charlie - It could be a good thing to have all these in the library for this forum - while they are free.

I have downloaded them all. with only one upload per post, I don't know when I'll get them all uploaded...
In the mean time:
Please find attached below:
Resistance of Flat-Plate Buildings against Progressive
Collapse. I: Modeling of Slab-Column Connections


SF Charlie
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[gonefishing2]

Nice Model and article from NY Times titled "The Surfside Condo Was Flawed and Failing. Here’s a Look Inside."

https://www.nytimes.com/interactive/2021/09/01/us/miami-building-collapse.html

Edit: Warning for some, No mention on Top First.......


Thank you for posting that particular paper! It appears my attempted post of this paper was a failure!

 

[SFCharlie]

Here is the shared code for the article above
The Surfside Condo Was Flawed and Failing. Here’s a Look Inside.

SF Charlie
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[IEGeezer]

According to the excellent timeline from MaudSTL (Computer):

Before 1:10 AM, there were "knocking" noises.

At T minus 12 (1:10 AM):
In 111, Sarah (office), Gabe (kitchen), and Chani Nir (shower) hear a loud crash, as if "a wall collapsed" in the condo above.

In the lobby, Shamoka Furman hears a loud sound that seems to come from the elevator, although the elevator throws no alarms.

At 1:15 AM, the deck collapses:

In the lobby, Sarah Nir and Shamoka Furman hear a "big boom." Sarah runs to the window to see "all the garage has collapsed...:"

In 111, Gabe and Chani, hear a loud crash.

In the elevator between the garage and the lobby, Nicolas Vazquez and Gimena Arcadi hear and fell the collapse.

Other than the Nirs, I believe only Ileana Monteagudo in the x11 stack survive. Ms. Monteagudo wakes up after the deck collapse.

What if, one of the balconies between the red lines below fails and falls, thus collapsing the pool deck. I hate to bring up the "falling object" theory again, but I am struggling to explain the "knocking" noises and the "wall crashing" before the deck collapse. What if the balcony was falling slowly, until it fell against the building, hanging by a thread and then collapsed to the pool deck, collapsing it and precipitating the rest? Just another thought.

 

[Debirlfan]

Expanding on the falling balcony idea - if a balcony collapsed slowly, pieces of it or items falling from it might account for the knocking noises?

 

[Spartan5]

If the deck started to fail progressively at the construction joint near the pool first, unzipping almost, it would account for knocking noises. Punch, sag, pull, collapse, punch, sag, pull, collapse, etc. until it got to the parking area, then a larger punch, sag, collapse (BANG) and pull before the columns give way and bring the whole building down.

 

[Nukeman948]

The problem with the falling balcony idea is that it starts with an idea in search of evidence. That is the type of flawed thinking that gets us looking at fuzzy pictures and seeing A/C units and tar-paper rolls when they just are not there.
A good theory always starts with evidence and works towards a viable explanation without confirmation bias.
It could be correct but the balconies are not simply glued to the side of the building but are a cantilevered part of the floor slabs with lengths of rebar extending far into the slab. I don't see them having any more chance of failing in a way that would trigger a collapse than other theories that have much more evidence and seem more likely.

 

[AusG]

I'm thinking the knocking noises could also be grab-and-release of surfaces grinding under load - say rebar prying out, or a crack or joints moving. The same process as creates creaking but more periodic. say: Pool deck progressive sag with catenary pull on the columns (could that find a fulcrum on first floor slab, stressing the second floor?), knocking, Nir's first collapse "above", pool deck gives up completely, unsupported and wracked columns buckle, general collapse of first section.

 

[MaudSTL]

Thanks, IEGeezer.

Also keep in mind that the knocking sounds went on for over two hours, and maybe longer. Chani Nir (111) heard them starting at 11 PM when she got home. We have no idea if Shamoka Furman or anyone else heard the knocking sounds in the lobby, or at what time the sounds actually started. So that 2+ hour duration would tend to favor of the slo-mo deck collapse pulling hard enough on a weak column idea over the balcony collapse idea.

 

[Jeff Ostroff]

I think the problem with the falling balconies is that when I see video of the security camera from 87 Park next door, as the condo starts to collapse, it looks like all the balconies are accounted for. I don't see anything out of place.

 

[Optical98]

Regarding the elevator noises, maybe knocking noises.. someone had mentioned before that the concrete blocks that made up the shaft walls, if the elevator shaft walls were damaged the blocks would fall down onto the elevator cars, thus creating 'noises from above'.

Good view of the stairwell

View to the right shows elevator shaft - this must be where the blocks were falling from?

I finally found a good pic of the deck below the stairwell door to the pool deck, I hadn't realized the deck had collapsed under the planter, you can see right into the basement...and the planter is still hanging to the wall!
[img [URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1630551464/tips/staiirwell_basement_aysp7s.png[/URL]

 

[Optical98]

Also, did we ever decide what these items on the roof were, this is a satellite photo est date 6/22/21, showing the roofing crane as roof work was still in progress.

What is that large round silver object?

 

[SFCharlie]

you can see right into the basement...and the planter is still hanging to the wall!

Here is where I could just use some them thar power-pointy arrows to see what you're talking about

SF Charlie
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[Optical98]

SF Charlie

Let me know if this helps, I have Power-point and have viewed pics on it, but have not Used PP for a long time..

The green lines are the planter and the red arrow points to the basement.

 

[AusG]

Yes. That is a planter and that is a stub of the deck still attached to the wall. The edge below your green mark is part of the collapse edge of the pool deck with a view into the carpark beneath. That collection of stuff shows up in a number of views of the rubble pile taken early on in the recovery.

 

[Optical98]

AusG

What is your point of repeating what I already said?