Miami Beach, Champlain Towers South apartment building collapse, Part 05 111

[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


SF Charlie
Eng-Tips.com Forum Policies

 

[AutisticBez]

Dude, the tree has a massive root system buried in the ground. And the car has a crumble zone that is weak as all hell. Can you see how the impact stops at the end of that crumble zone? Tree's are much stronger then columns surely?

 

[Awestruc]

I don’t see how unbonded PT tendons that are stretched to 70%-80% of their ultimate tensile strength can offer any shear strength. They would be under extreme tension + shear = pop.

Modern connections are more robust due to the use of stirrups or stud rails or puddling of high strength concrete atop columns (questionable).

The pool deck design had no real shear reinforcement. The design concept was
To design the concrete thickness to handle the shear. Then to design the horizontal top bar for flexural tension, and then place a certain amount of horizontal rebar directly over the column for good measure. This is the same philosophy with modern PT.

 

[zebraso]

Does anyone see the black stuff In the middle of the rubble. I thought it was a contiguous object at first but then I think I realized that some of it is interspersed with shadows due to the lighting orientation amidst rubble, and it just looks like a continuous piece of something. And then for some unknown reason I thought of roof paper rolls. And then I looked at it a bit more. Thing that bothers me is that I did not look at it with the idea of finding roof paper rolls. I was not looking for them.

 

[spsalso]

From AutisticBez: "Like, say what you will about the connecting rebar on the pool deck to the columns, but those columns survived an entire pool deck slamming down on them from above."

No. It was not "above". It was at the same height. There was not "slamming down on them from above" by the pool deck.

If you disagree, please state the height of the pool deck above the columns.


spsalso

 

[spsalso]

zebraso,

I am missing your point. I think it's been said there was roofing paper rolls on the roof. Everything fell down, with the roof pieces on the top. I would expect the rolls to be there, on or near the top of the pile.

Please explain why you are surprised.


spsalso

 

[gonefishing2]

https://res.cloudinary.com/engineer...Champlain_North_Parkade_comparison_vjlqdp.jpg

Now that your mention it, I think I see the rolls of roofing paper in the middle of rubble.

 

[gonefishing2]

 

[spsalso]

It appears the NIST is doing a stealth investigation. It's over 10 days, and no news conference.

Are there cameras recording the debris removal? Where is it being taken? Is it being keyed in any way to the location where it was found? Are the NIST investigators on site? What are they doing when they are on site?

Did NIST approve of the standing building's destruction? Did NIST collect evidence for their investigation prior to the destruction? How did they do this?

What is the name of the lead investigator? What are the names of the other members of the team (approximately 6, I believe).

Why has it taken over 10 days to hear from these investigators?


spsalso

 

[Ingenuity]

I don’t see how unbonded PT tendons that are stretched to 70%-80% of their ultimate tensile strength can offer any shear strength. They would be under extreme tension + shear = pop.

1994 Northridge earthquake - PT integrity tendons support severely damaged slab:

 

[Js5180]

JBourne, no, it wouldn't be at the th in "both." If that was the case, the columns would be equidistant in the photo. But they are equidistant in real life, which means in the photo, you have to account for perspective. Each subsequent column in the tiktok video is about 2/3 the distance from the lsat, from the photo's perspective. That moves the M11.1 (which I was calling M11) aa little to the left in the tiktok, to about the "BOT" in the "BOTH" but definitely not at "OTH."

 

[AutisticBez]

The columns survived whilst the pool deck is a shrivelled up mess. Figure of speech. The columns are strong, the pool deck was weak. The rebar in the pool deck, also weak. They added to the dead load of the pool deck by paving over it. But the columns under the pool deck look strong. Too strong. Like, why would you need such thick columns under a pool deck?

I guess I don't believe falling debris from the roof is capable of making an entire column disappear. This to me is something else. Could a car cause a column to dislodge from the top and bottom?

 

[zebraso]

Please explain why you are surprised.

Sorry about that. I wasn't trying to be elusive. After I posted it I realized I left out the context. I meant to post as an ongoing description of what is in the tic tic capture that has more recently been under review. I mean to describe what occurred to me as it appears in that enhanced capture. So that in effect this would describe roof paper rolls in the basement before the main structure collapsed. I meant to look at it as objectively as I could. But what I think I see is roof paper rolls and then as mentioned before in the thread, not far away in the basement is what appears to be a material that is the color of the tarp that was used to cover said rolls. If anyone mentioned the appearance of the actual rolls in the basement before I missed it.

 

[spsalso]

Thermopile,

Yes, I see that too. I am sure our NIST investigators will, uh, investigate. And perhaps confirm it's rolled roofing.

They are PROFESSIONALS, damn it!


spsalso

 

[Js5180]

Also, if anything in the tiktok could arguably be a CMU, well, then we have a roof-first event...

 

[gonefishing2]

The left side of image looks like 3 rolls of tar paper all lined up, with slight angle changes between rolls

 

[spsalso]

zebrso,

I see the problem. You said "in the middle of the debris". Debris to me is the big pile at the former building site. You are talking about some debris in the parking area, down the ramp. I think.

Yeah, that surely could be roofing paper. Or something else.

Rest assured, the NIST is on the case!

 

[gonefishing2]

Then that could mean broken column is leaning onto Square planter from above

 

[jbourne8]

Maybe that'd be a good experiment too, toss a bag of roofing rolls on the ground from a few stories up and see if you can get them all to land in one spot. Looked like some sort of metal bar to me.. maybe a deck umbrella? I'm not sure anything on the floor of that tiktok video can be positively identified, except for maybe the column and planter since we know exactly where they'd be. Is this all we're going to discuss now? I'm not sure I see the point when the video is at such low resolution.

It's interesting too that it sounds like Cassondra was in 410 and she only described it as a sinkhole under the pool deck, instead of the upstairs parking area as well. It really makes you wonder how extensive it was when she made that call.

Js5180, I think you're underestimating how far apart the lengths would descend from this perspective.. either way, it can easily still be that white object at the bottom of the pile of rubble there.

Thermopile, How would the column end up on top of the planter though? It's also too far back.

 

[spsalso]

Thermopile:

"The left side of image looks like 3 rolls of tar paper all lined up, with slight angle changes between rolls"

That is some quality roofing paper, to remain (semi-)usable after a fall like that. I should get the manufacturer's name.


spsalso

 

[gonefishing2]

I was figuring planter rolled on way down, and column did not fail immediately?