Miami Beach, Champlain Towers South apartment building collapse, Part 09 139

[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

SF Charlie
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[Demented]

Original, since it wont let me upload it there.

Some odd stuff.

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

 

[Optical98]

There goes Demented showing off his pixels.....

Can u expand out a lil, where are we, on the roof, pool deck?

 

[Spartan5]

MaudSTL.
A suggestion;
Add a column for the identity of contributors.

Please put me down for gravity. Thx!

 

[gonefishing2]

None of those pixels look like tar paper... They look like multiple layers of elastomeric roofing material?

 

[gonefishing2]

And we all know 'Gravity' can be a bitch!

 

[Demented]

Watching the BI video, if the slabs failed shearing down the shear wall in such a way, where are the marks of concrete against concrete? We've see scraping along the columns where slabs failed, as well as along other walls such as in the deck. I just don't see indications of shearing along the wall, as is evident as well by portions of slab clinging to and hanging from the wall. We know this are of the building also twisted in the opposite direction we would expect to see from a shearing like that. Those slabs hung on for dear life until the rebar reached it's tensile limit and snapped.

It looks to me as though it tore away, not sheared, initially at least.

At this point, I am more inclined to say the collapse originated around the E-H column span leading to upper floors collapsing, sending massive shock loads to the base of columns before the deck and possibly portions of the lower slab elsewhere in the parking garage, failed, hinging where the slab is offset, causing the pool side of the building to collapse which brings what I believe to be the 4th section collapsing down, and finally the east most wing as it was top heavy and unstable. If it were not for the elivator shaft, I think it's likely we would have seen the entire structure come down.

@Optical98. Download the original. I don't know why but uploading images turns even high res to potatos here. It's a whole lot more clear.
Top of the rubble pile, day 1, first responder photo.
3024 x 4032, iPhone 11.
So we at least have some decent quality.

 

[gonefishing2]

I think we need to realize with MarkBoB2's calculation, that plastic Green and yellow handled bag is just the right 2500 lb static test load for a 5000 PSI rated OSHA roof anchor???

 

[Demented]

Hanging off of a hot tar roof that was many layers thick with anchors driven down into the roof covering, and not the slab. Almost feels like we've been there before.

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

 

[Optical98]

Demented, I think that bottom black layered bit is part of a broken window frame.

 

[Demented]

@MarkBoB2, 60lbs per roll.

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

 

[Sym P. le]

@Demented, You are correct in thinking that pure tearing as displayed in the paper analogy would leave scrape marks along the shear wall, however that is a very black or white perspective.

In a previous post, I noted a void in the debris pile as if the remains of section 1 disappeared. We now know for a fact that there is no sinkhole that swallowed them up. Rather the pull of the collapse was significantly to the NNE.

I'm not an expert, but someone else posted a collapse video that showed just how much a weak side of a failure can be pulled aside so the question is which side of the collapsing section has more pull. We already know the answer in this case, but this raises the question of why was the big strong shear wall unable to exert the greater pull. The BI analogy nicely answers this question.

 

[Spartan5]

20 rolls per pallet is typical for the heavier stuff.

As in the picture of the pallet on the roof above, they are 4 wide x 5 deep. I’m not sure how anyone sees 7x7.

20 per x 60# = 1,200 lb / pallet

 

[Demented]

@Optical98, I don't think it is. Next to it you can see a portion of window/door sliding frame and it is different. Layers of tar appear to be on it which I can't imagine was used along side it. This layering is also evident near the elivator shaft.

@Sym P.Le
Black and white perspective indeed. It's just odd to me that we see it elsewhere in the collapse, but not there. Roof Area 2 was the only reroofing this year. Was this area recently installed with anchors? I ask because in previous threads it was speculated that weight may have been hung off an anchor above this area to load test the anchors. This was a thick roofing section per the plans. I know they weren't supposed to put anchors here, or yet at least, but their judgement in placement could have been better in places. Also, why are there instructions for full depth slab repair included in the roof anchor permit? What roofer is going to be shoring, doing full depth replacement, and epoxy injection? There are some large, rubberized hoses that can be seen near the roof anchor in the photo I posted.
Now, I have engine parts and tools all through my apartment, so I am in no position to discount someone else having what appears to be air or hydraulic lines in their unit. However, why was an air compressor recovered with roofing equipment? Seems they had gas powered sweepers and blowers, electric hammer drills and impacts. What is the air for, other than for epoxy injection?
That building inspector on the roof the day before would definitely know.

 

[Optical98]

Demented, my guess is a nail gun.

 

[Demented]

But what were they planning on nailing in the "ROOF & FACADE MAINTENANCE ANCHOR SYSTEM"

You wouldn't nail more tar paper down into the existing roof and hot tar over it...would you?


Edit: Sandblasting? Still curious how instructions this detailed for concrete repair got into the roof anchor install. Nail 2 birds with one stone?

Lets all read this aloud shall we?

dik pointed this out in thread 1.

Edited:

 

[MarkBoB2]

Spartan5, the standard pallet in the roofing industry is 48x36 in. Looking at my photo above, each side is 2x36 inches. So one may conclude that the wooden base is not a standard pallet. You can easily count the rolls of tarpaper in each direction in the photo I provided. I counted 7 in each direction.

 

[Optical98]

Demented, there was roofing equipment/supplies all over that roof, I think they were covering more than just section 2?

 

[Demented]

96"x48" is a pretty common pallet size used by distributors of this area. Concrete will still be on 48"x36" pallets to keep the weight down for standard forklifts. A 96x48 pallet would give you 32 rolls +/- 1. ~2000lbs.

@Optical98
Covering yes. Section 2 was just a full reroof as it was the most water damaged per the reports.

 

[MaudSTL]

I have had a better idea for how to build a spreadsheet that doesn’t require anyone (me) in the middle holding you up: a Google Form that automagically writes to the spreadsheet!

1. Complete and submit the Engineering Input Form

Screen Name
Type
Sub-type
Theory/Hypothesis <short description>
Proven Evidence
Possible Evidence Not Yet Proven
Argument Against
Notes/Links​

Tip: Check the spreadsheet to see if your Theory is already listed. If it is, use the same Type, Sub-Type, and Theory/Hypothesis so that sorting will place your entry by the previous listing. There is no limit on how many listings a particular theory may have.​

2. Review the CTS Collapse spreadsheet to see your entry/entries and everyone else’s entries.

I have the input form set up to accept your screen name (thanks to all who recommended that) so that you should be able to make as many entries as you like.

We will use the Type/Sub-type fields as organizers. This will allow us to sort the spreadsheet so that related items will appear next to each other. This will be more efficient than human intervention to organize separate tabs, although we could do that after we end submissions.

Please let me know if you think any of the fields need to be updated or if anything doesn’t seem to be working properly. Have at it!

 

[Demented]

@MaudsSTL
As there is a lot of stuff located within PDF files on the Surfside website, perhaps a column where links to supporting documents can be included? Or would that fall best under the "Possible Evidence Not Yet Proven" columns?

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