Miami Beach, Champlain Towers South apartment building collapse, Part 16 24

[dik]

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Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[FJBnomics]

I don't remember seeing this, but then I do not subscribe to MH.

https://www.miamiherald.com/news/special-reports/surfside-investigation/article256178672.html

 

[SFCharlie]

In the "with corrosion" image, What's that in the north west corner? Isn't that one of the early failure locations as seen the collapse video?

SF Charlie
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[FJBnomics]

Could be, I have slept many times since then..........., meaning I have forgotten, and need to watch video again to see what you mean.

 

[Jeff Ostroff]

With the flurry of news going on this week, did any of you notice that the City Of Surfside decided to kick in $2 Million also? I don't think they are named as a defendant in any lawsuit, but they wanted to do it and confirmed the vote the other day in a rare Monday morning vote

 

[stcbus]

Any updates on the other sister towers and if shoring is still there or what's been going on? When I was in Miami a couple weeks ago I really wanted to visit the sites, but figured it'd be a waste of time since I wouldn't be able to get in anywhere.

 

[Sym P. le]

Again, the MH graphics are not worth the ink or pixels. They start with a premise that did not exist and continue down that rabbit hole on a lark that the neighbour brought down the tower.

 

[Sym P. le]

Morabito and his team inspected Champlain South frequently between 2018 and 2021, taking photographs and writing nearly half a dozen reports noting the pool deck slab was in urgent need of repair.

Do we have all of those reports and supporting material?

 

[FJBnomics]

I agree MH modeling may be off base with their Assumptions, as they don't reflect 'As Builts'.

However, I find it very interesting that the 'As Designed' Model shows cracks in the areas of interest that seem to align very well with the current evidence we have, except for South Wall (which I have hard time believing we have the deflections in red they show along the wall, with it still standing?

So yes take it with a grain of Salt, but I don't think you throw the whole thing out either at this point.

 

[Sym P. le]

Actually, it is better to throw out their model. MH can update their model to help folks understand how this building fell down and why theirs won't. Regarding vibrations from the neighbour, it is possible that it impacted Champlain Towers but it didn't cause CTS to be constructed in a way that it wasn't or lend credence to machinations that a concrete slab, regardless of reinforcing, has less strength than who knows what when continuously supported by a concrete wall. The complex stress patterns developed in a two way slab with a variety of support and stiffening elements are better visualized with a proper digital model than imagined.

Structural Madness's model, though also imperfect, lends better insight to this collapse. Note how the deflection across the 30' span creates a high stress zone along the south edge of the 13.1 columns and north edge of the 14.1 columns. This is consistent with the evidence seen regarding the planter and column 76.

 

[FJBnomics]

Agree with you again, as I just thought of the water loading on top of the deflected slabs, and how much more load that added beyond any design calculations for dead weight and 'standard' live loads of so many PSF.

I guess what intrigued me was the linear crack in line E-W with Column I, which was NOT mid span.

Edit: I Yield! You are right! Yes Vibrations add a whole other complexity, even different from parking deck cycling.

 

[Jeff Ostroff]

With an inch or so of sand under those large pavers on the pool deck, neither of which were in the original design model, they were added in 1996, I showed on one of my July videos how the sand layer beneath the pool deck can obviously retain a lot of water weight. Even days later after rain, it still would be moist with some water, adding a lot of weight at 8 pounds per gallon.

Every time it rains the dynamic weight load goes up and every time it dries the weight load goes back down. Seems to me like the slow-motion bouncing of a trampoline.

 

[Sym P. le]

I wonder if during a rain event, the 30' span had enough advantage to pull the other bays tight, thus amplifying its ability to collect even more water? Or in other words all the storm water made its way to the 30' span.

 

[MaudSTL]

Episode 11 of the Miami Herald’s podcast talks about the planters.

 

[FJBnomics]

Interesting thought about water load on 30 foot span, and I would think so, and when it dried or leaked thru garage, it would have shifted the balance some the other way, which would appear to induce even more stress and cracking.

I also wonder if the E-W rebar was actually the final straw that broke the camel's back. Specifically the drop of the planter could have been the E-W rebar loosing it's grip at Column I14 connection. Once it lost grip, the other columns were already in partial punch and ready to go.

 

[zebraso]

About episode 11 (MH podcast) The narrator says part of the number 76 on the column has been "smeared off". I imagine that is in the sense of washed away or something. No. It is partially covered with efflorescence deposited by supersaturated water trailing down. The calcium carbonate just happens to be the same color as the white paint. What is on that number is the dissolved skeleton of the structure.

 

[Sym P. le]

No. It's deceptive seeing that long east/west alley but that's not how to analyze it. If you check the larger graphic on the video, you will see that the gradient is not as steep at the west end, therefore less strain. The 30' span is doing the heavy lifting with a particular stress point at the column edge.

Edit: I may have spoken to soon. The column you are looking at is misplaced in the model so it doesn't reflect CTS exactly but the results as presented are interesting.

 

[spsalso]

"With the flurry of news going on this week, did any of you notice that the City Of Surfside decided to kick in $2 Million also? I don't think they are named as a defendant in any lawsuit, but they wanted to do it and confirmed the vote the other day in a rare Monday morning vote"

Of course not. Their Building Department appears to have done something close to nothing in ensuring that this building was properly built, but also accepted $40,000 in permit fees to ensure that it WAS. It just MIGHT be a little short, dollarwise. And then there's criminal negligence:

If you accept money to do a job (inspect a building during construction), and you don't do the job (by delegating the PE to inspect his own work), and people die because there were flagrant construction errors, does that not sound like criminal negligence?

I could be in error here in my assumptions, so please correct me if I am wrong.


spsalso

 

[IanCA]

Thanks stcbus.

Episode 11 of the Miami Herald’s podcast talks about the planters.

Thanks MaudSTL.


The statement that concerned me in podcast Episode 11 was this at 17:50: "This exact same area had been photographed a little over a year before, in April 2020, and in those pictures, there is no sign of the cracks, at all."

But when I zoom in on the April 2020 photo, there certainly looks like some signs of prior damage to me.

And I think the area that Josh described as 'blurry' needs further study to understand why the horizontal crack is not clear in that area. It doesn't look like any of the usual optical or digital artifacts. Perhaps it was another area with prior repairs?

Suggestions welcome.​

 

[FJBnomics]

I did not notice this localized sinking of planter area only, until this posting of the previous bondo repairs was pointed out. The whole area of planter has dropped like into a sink hole (for lack of better analogy).

So I will ask, could we have dissolved rebar grid in this area, which just happens to line up with column Line I14? We know we have a diagonal crack headed to this area from the parking deck.

So loss of a square of rebar grid/concrete failure in this area, could lead at first to localized drop.

Loss of grid in this area, would appear to start transferring load to surrounding columns. Which in this case are K13.1, K15, and I14. Which breaks the rebar tight rope in this area, and now 1-3 columns at once loose what little punch shear resistance rebar they had on at least one side of each column,

Boom!

 

[SFCharlie]

SF Charlie
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