Miami Beach, Champlain Towers South apartment building collapse, Part 11 54

[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


SF Charlie
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[TheGreenLama]

Regarding sounds.

Can punching shear failure occur in slow motion?

Back when Dik posted the pic of the MC core sample it didn't register w/ me at the time just how odd that sample was. It wasn't until I watched Building Integrity's video, where he mentions that ALL of the cores looked similar, with rebar loose within the core, that I realized my oversight.

Picking up from Building Integrity, IEGeezer points out above just how stressed that one pool deck column line was (the one that is also missing a drop down beam), as well as having the smallest columns. So if we assume that the slab around column K13.1, also the most highly stressed area, failed in punching shear first, could this occur in relative slow motion? By that I mean, not being immediately obvious, except for the sounds. Could it then progress to column K12.1, again not being obvious, except for the sounds? If so, at this point it would begin to impart thru catenary action horizontal loads onto the main building column (this by the way was previously posited way back in the thread).

RandomTaskkk addresses column failure and load redistribution leading to sound generation throughout the building. Could a sustained horizontal force on the column also lead to sound generation? The time frame of all this is what I don't understand.

Then, just speculating here. Garage level still may look relatively intact. Pool slab is still pulling on column, but nothing has fallen yet. Now slow motion punching shear progresses east from column K13.1 towards the pool and the construction joint that exists in the deck slab. At some point that section fully drops and becomes visible from the garage ramp. Then other sections of slab begin to drop and all hell breaks loose.

Of course many things are POSSIBLE, but I thought I'd just add that to the mix.

 

[zebraso]

250 lb safe

Thank you. A little perspective I guess. I thought I just read EST was 13 stories after I said it wasn't whatever. Actually that would make a difference with m/s/s and all. I think he jumped the shark after the velcro suit.

 

[Spartan5]

EST proper is 13. But wherever they were dropping from was 7. I counted them. But I don’t have a PowerPoint of it for you

 

[Spartan5]

Regarding sounds.

Can punching shear failure occur in slow motion?

That’s my beat guess for the noises. Slow progressive failure of the deck as it worked its way towards the building. Possibly originating at a construction joint nearest the pool. Culminating in a more rapid failure as it hit the weak spots in the garage and near the planters. Which then brought the rest of the building down within a couple of minutes.

That would explain the noises growing louder. And how elements of the initial failure weren’t visibly apparent. Unless you
Happened to be looking at the pool from a balcony perhaps.

 

[zebraso]

That's good. Makes sense also. As fuzzy as my memory was on that stunt I could not have imagined from memory that they were dropping crap from 13 stories. PPT. yeah right.

 

[TheGreenLama]

Having mentioned possible slow motion punching shear failure, let me also add several questions surrounding that scenario:
1) From photos of the pencil-like column tops in that area, the fact that so little slab concrete appears to have been engaged makes me wonder how 'slow motion' the failure could have been.
2) This may have been discussed before, but you'd think the fire suppression lines in garage should have become activated.
3) For the pool slab to hang/drape it must be supported somewhere. That would require a patchwork failure at first.
EDIT: 4) Lack of integrity reinforcement above the columns.

Unless, as you say Spartan5, the failure progressed from the rear of the garage towards the building. But then all that creaking in the building remains a mystery.

 

[Spartan5]

But then all that creaking in the building remains a mystery.

There isn’t much to me that’s definitive in another of that reporting. Most of it seems pretty inconsistent.

As for the pencil columns, it makes me wonder how the deck stood for 40 years. So it also seems possible that there was enough strength in those poor connections to allow for some load transfer and incremental failure as well. What would it sound like as each of those columns popped and the deck sagged/collapsed a bit more?

 

[SFCharlie]

A graphic tool for analyzing the debris pile with red paint on objects located at the bottom of the resident parking garage ramp.
With glossy photographs with circles and arrows and a paragraph on the back.
(Oh No, Not another powerpointy du-da)
from the 1979 plans, the location of approximate square of columns.

1979 dimensions of approximate square of columns.

Rectangle showing the 1979 dimensions on the outtake from the video.

zoomed in on the pile overlain with a one foot grid in blue.

Not to put too fine a point on it, the objects in the pile are small.

 

[MarkBoB2]

SFCharlie, Thank you for all your work above. I agree with the scale you show. But your green square doesn't agree with any of the objects that I have identified. The downward-pointing arrow to the left of your green square is what I have believed to be an AC condenser. And the arrow below it pointing to the 11:00 o'clock position I believed to be the top of the AC. Both of these objects are tilted, so it is difficult to get a good idea of their dimensions. But I agree that they are smaller than I expected. I measured that the diagonal of the top was about 20 inches. And I measured that the diagonal of the condenser was about 22 inches, with a hole about 10 inches in diameter. This probably means that this object is not an AC. Do you have any ideas of what it may be?

 

[SFCharlie]

your green square doesn't agree with any of the objects that I have identified.

Your very welcome. I just do it for the fun of it...
The green square is the size of the base of one of the traffic cones. I largest traffic cone I found on google was 36" high and 14" square at the base.

edit: I agree, they are probably not part of an air conditioner. If I were you, I would use power point to draw lines or arcs to show the edges on the objects. I use the rotate shape to align the pp shape with the image. Also, after selecting a shape, I use "shape format" to "edit shape">"edit points" to get everything to line up. Sometimes this helps my mind recognize stuff.

 

[MarkBoB2]

SFCharlie, I agree with your cone dimensions. This was how I estimated the dimensions above, by comparing them to the cone dimensions.

 

[MechinNC]

Please ignore my knucklehead mech engr question (although I have a lot of failure analysis experience, just not on reinforced concrete):

So it seems a popular theory is that the columns punched through the patio deck and as it failed it tugged on some main building columns which were now damaged at failed slab joint, and now those columns had much greater unsupported length. Failed in buckling, especially with the discontinuity where the slab used to be attached.

So the question: If that patio slab was so degraded that punch through could happen, would you not expect to see deformation on the upper slab surface right over the column, for at least some period of time? With the standing water common on the patio surface, you would expect to see bulges or dry spots right over the columns??

As the column to slab joint overstressed one would think there would be deformation before failure?

I'm having trouble with how concrete behaves in failure and this time element between clues and total failure. I would think that failure would be more sudden than drawn out over several minutes.

Maybe just showing my ignorance...

 

[SFCharlie]

I'm having trouble with how concrete behaves in failure and this time element between clues and total failure

Many of us are having trouble putting the witness statements and what limited evidence there is together into a straight forward understanding of the collapse. That why MuadSTL put together a spreadsheet (link upstream) of the times of the witness experiences. The YouTube channel "BuildingIntegrity" has a video that takes one through the garage video tour under the pooldeck, showing the cracking in the structural bottom layer of the deck slab. It's necessary to have an awareness of the history of the pooldeck. Apparently, the as built had a layer of non-structural concrete with a brick pattern stamped in it. Then a layer of sand and then pavers was installed sometime latter. The sand may have hidden the distortion going on underneath.

SF Charlie
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[12345abc6ttyui67]

Do you have any ideas of what it may be?

Literally every 'chunk' in the "Slide 10" photo is just smashed up concrete.

 

[Jedidad]

If that patio slab was so degraded that punch through could happen, would you not expect to see deformation on the upper slab surface

A YT channel named Construction Engineering & Failure Analysis (

https://youtu.be/djePOXALegM)

talks about this. You can actually see what looks like deformation in the pool deck in some of the photos. Or maybe it was designed that way for drainage.

 

[Sym P. le]

Maybe that deserves a second look.
The tile installation would not have been so abrubt while the weight of the installation could have set that off in the days/months after.

 

[gonefishing2]

The tile installation would not have been so abrubt while the weight of the installation could have set that off in the days/months after.

When Demented was looking thru all the maintenance and repairs, one was the tear out of the pool gutter system and installing a new gutter system which appeared to be higher in elevation than the original one. I think when the raised the perimeter of the pool and hot tub, they added probably more sand to raise the patio tiles to match the elevation of the pool and tapered the deck from new pool curb height into the rest of the patio deck. I know in some pictures I have seen, way back in this long thread, it looked clearly like the area around the pool and hot tub was higher elevation, and tapered back into the rest of the paver level on patio deck side of the pool.

I don't think what you are seeing is structural deformations below.

Perhaps Demented has the info handy to confirm my memory?

 

[SFCharlie]

(replying to(MechinNC))
A YT channel named Construction Engineering & Failure Analysis

"Construction Engineering & Failure Analysis" works very hard to find sources of information, and, I guess it's not surprisingly, keeps his sources very close to his chest, refusing to share them. In searching for myself, I discovered this site. He scours this site for input. I strongly suggest new posters read or at least scan previous posts of this thread!

SF Charlie
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[gonefishing2]

"Construction Engineering & Failure Analysis" works very hard to find sources of information, and, I guess it's not surprisingly, keeps his sources very close to his chest, refusing to share them. In searching for myself, I discovered this site. He scours this site for input. I strongly suggest new posters read or at least scan previous posts of this thread!

I first found "Construction Engineering & Failure Analysis" You Tube videos back either on FIU Bridge Collapse or Hard Rock in NOLA.
After suffering thru one of his videos, I have never listened to his mind work, out loud, in real time on You Tube again.

I highly recommend this Forum, and You Tube Analysis from sources like "Building Integrity" over a lot of other chatter on the internet. Yes you might find some good information or alternative ideas or pictures on other sites, but you must sort thru the noise to find a valid signal!

Edit: But problem is, a lot of the conclusions or ideas are provided based their cited, but not disclosed, calculations and assumptions. Point is there is a lot of difference of opinion out there, but no none has hit the ball out of the park yet! Further Miami-Dade has locked down the information sources, thus there is not much to go on with grainy pictures and the screened and selective documents that were released to the public.

 

[SFCharlie]

I also saw this of interest. Waterproofing, paver installation and garage repair in 1996.

I don't know if this is the earliest...


SF Charlie
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