Miami Beach, Champlain Towers South apartment building collapse, Part 13 44

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


SF Charlie
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[Nukeman948]

The original slab and topping were buried under a second slab, topping, and pavers.

I noticed that too but the pool and Jacuzzi are different on the prints I have and there may be differences in the slabs here. Your slab #1 may be the structural slab and #2 may be the topping slab with waterproofing, sand and tiles on top. You are right that only part of the slabs punched through column 37.

 

[Jeff Ostroff]

Guys here is a closer zoom-in I made, so it looks like we have our 9 1/2" slab, but then looks like we have about 4" of additional slab on top, and then about 2" of sand/mortar bed, then 1 1/4" thick pavers. Should be concerned about his 4" slab? This is the first time we have seen this as it is not in the plans.
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[Jeff Ostroff]

No, I think I was looking at the thick reinforcement concrete for the pool corbel in that previous picture. This newer mockup here shows the pool deck. But the pool deck only looks to be 6", not 9 1/2". I forget which page on the floorplan shows pool slab thickness, but I thought it is supposed to be more than 6".

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[Sym P. le]

Perhaps the garage video has some insight on this? If the upper slab is the deck slab as we've been led to believe, and the lower slab is pool zone reinforcement, there would have to be a step in the underside.

It seems odd that the column slab reinforcement did not tie into the upper deck slab, if that's what it is.

I've just thrown this out there without any research but it seems odd. Maybe there is an explaination.

Thanks all.

 

[Jeff Ostroff]

Yes, it looks to me like they did not pour all the concrete at once. Instead, it appears there is a cold joint where that thicker reinforcement part of the concrete on the left of the photo lines up underneath to the pool deck, which we still don't have a confirmation on the thickness, but you can see a definite line between the two which says to me they did this in 2 separate time spaced pours. Not sure if that is a problem or not. there may also be another set of "as-built" plans by the contractor to tell the framing plan for this extra thick concrete that we don't see in any of the drawings.

 

[Jeff Ostroff]

I made a screenshot of the garage video of space #37. A nice car parked there. Can't tell anything through all the pipes
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[sgw1009]

The columns in the garage are 12"x12". That can be used as a reference to help determine the other dimensions.

 

[Nukeman948]

Morabito only shows the 9.5 inch slab and pavers with no topping here: (page 24 of preliminary-review-plans-for-40-year-re-certification). So it seems they failed to do enough research on the existing structure. Of course we don't have any details of how this area was originally built or designed either and the topping may have been thinned in places to provide slope for drainage for the pool.
This could explain why they wanted confirmation of slab thickness at the pavilion location and why they failed to understand the importance of drop panels in more locations than their preliminary plans show.
They may have some serious liability unless they can claim all this was outside their work scope or more revisions were coming.

HEY JEFF, Perhaps you didn't see SFCharlie's request for the URL to "over 100 photos shot on the condo collapse site a few days ago"

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1632584321/tips/Pool_area--preliminary-review-plans-for-40-year-re-certification_eh93up.pdf[/url]

 

[sgw1009]

From 9:30 in Jeff's video above, if the column is 12 inches square, then the top slab appears to be about 6 inches thick, with the sand layer above it about 2 inches thick. This is also using Jeff's earlier post ("Guys here is a closer zoom-in I made...") to judge that the top slab is about 6 inches thick. Towards the left of the shot, the two slabs are shown close together, and the lower slab also appears to be about 6 inches thick, with the layer above it also about 2 inches thick. This would make the total thickness about 16 inches thick, not counting the tiles.

Edit: Perhaps the line part way up the bottom layer is not a new layer, but just where the rebar was. So perhaps the bottom layer is all one layer, about 8 or so inches thick.

 

[Nukeman948]

The columns in the garage are 12"x12".

The column schedule does not show any 12"x12" columns. It could be 12"x16" but I can't find a clear confirmation of what size is called out for this location. Can you point to it?
As-builts have not been found and I wouldn't trust them anyway. Field confirmation is the only way to know for sure.
The collapse didn't begin here so I'm not really understanding where this discussion is going.

 

[sgw1009]

Here is another long shot cross section of the pool deck near spot 37. It gives a little better view of the comparative thicknesses of the deck layers. This is from Jeff's video at 10:49.

 

[Jeff Ostroff]

Guys from Because Surfside sent me the photos, they obtained them through a Freedom Of Information Act request from the Town of Surfside, and I used them to make the video.

 

[sgw1009]

Here is a closeup of the image I posted earlier. It is zoomed in to the corner that shows a good view from afar of the layers of slab. And a reference for comparison, the Yodack traffic barriers right above that area are 32" tall and 6 feet long.

 

[Spartan5]

Guys from Because Surfside sent me the photos, they obtained them through a Freedom Of Information Act request from the Town of Surfside, and I used them to make the video.

Will you zip up the originals and post them here?

 

[SFCharlie]

There are over 100 photos shot on the condo collapse site a few days ago

Yes Jeff,
I understand that you may wish to wait until you have posted your next video, but the images need to be archived here, so we can zoom in and look for tar kettles, cranes, washing machines, AC's, barbells from the gym, secret spy drone wreckage, Godzilla footprints, and heavens know what else.
All kidding aside, please, in good time, attach a zip file here.
Thanks

SF Charlie
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[Red Corona]

We know about the topping slab from the core samples, don't we? Interesting that it appears the (non-structural) topping slab survived for a few feet over that column '37' when the structural slab puncture sheared though.

That isn't the initial failure area but it's interesting how there seems to be very little rebar in that deck slab at all. The deck didn't fail, but the lack of deck rebar running through the columns would make the joints with the columns less able to resist the shear. That lines up with what we've seen in earlier threads.

That whole L/M 11.1 area of interest has already been cleared down by the point these pics are taken so I'm not sure we can really see anything new. It's interesting how there seems to be one column in the 9.1 line (L? I think?) which has been cut off at ground level rather than the 2-3' of rebar that's left on all the others.

 

[Nukeman948]

It's interesting how there seems to be one column in the 9.1 line (L? I think?) which has been cut off at ground level rather than the 2-3' of rebar that's left on all the others.

This is also where I believe the initial failure began.
A slow compression failure beginning 22 hours earlier at this column may have gone unnoticed and would shift it's load to surrounding columns and fit the timeline of the first sounds of failure. The column wouldn't deform much because the rest of the structure is stiff enough to support it for a while. Then as the burden shifted through the pool deck to M-11.1 and L-11.1 columns (as well as all other adjacent columns) they would be next in line and fail by punching shear as the failure began to speed up. Then it's dominoes.
I think it is possible that M11.1 punched through the bottom of the planter above it and the mud from a weeks worth of rain coated the column and debris, adding to the confusion of what we see in the Tik-Toc video.

Punch holes in my theory. That's why I posted it.

 

[Jeff Ostroff]

OK Guys, Use this link to all the photos I used in my video, that we've been referencing that I posted above, for the last 2 days.

https://drive.google.com/drive/folders/1-0gDmnl4AWeyT80E6rrTiviXKwYSLy4u?usp=sharing

I'm sure Kai will be by momentarily to steal them and continue to claim everyone is stealing his ideas, he has a knack for grabbing other people's videos, showing it on his channel under the phony guise of critiquing/commenting on them, he's trying to game Youtube's algorithm by putting these high traffic videos from other channels on his. But all he does is criticize and condemn people in his videos. He even said Allyn Killsheimer is a liar and called him names, and says he does not know anything. He also lied and said the security guard's story is made up, that she never rescued anyone. He never watched the police bodycam video I posted, showing the arriving officers found her in the collapsed pool deck escorting out an elderly lady, she climbed herself up from the pool deck.

 

[SFCharlie]

Jeff
Thanks!

SF Charlie
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[sgw1009]

Interesting collection of concrete pieces in images 328, 330, 331, and 332 of Jeff's Google Drive photos. The pieces on the left are marked in blue, and the pieces on the right are marked in red. One of the red pieces is also marked "K13.1". What could be the significance of these pieces, and why are some red and some blue? The pieces are resting near the vestibule, and for certain column K13.1 was not originally located near the vestibule. So that indicates that these pieces were from somewhere else in the building (garage?) and were moved to that location for storage.