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Miami Beach, Champlain Towers South apartment building collapse, Part 14 41

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SFCharlie

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

SF Charlie
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That day, under .2" if I recall correctly. Workers on the roof did leave early due to weather, but it was also very gusty that day.
Rain was heavier the prior days.
 
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At the airport, precipitation from 6/10-16 was 1.6” and from 6/17-23 was 1.94”. 1.1” of rain fell two days earlier, on 6/21. It was very gusty prior to the collapse, going all the way back to 6/14. So for two days before the collapse, there was a lot of water sitting in the deck at the same time as the roofers were drilling into key columns and the wind had been gusty for nine days. It rained heavily on 6/24, after the building had already collapsed: 0.58”.
Precipitation
10 0
11 0
12 0
13 0.09
14 0
15 0.79
16 0.72
Total 1.6

17 0.61
18 0.03
19 0
20 0
21 1.1
22 0
23 0.2
Total 1.94
 
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There was a weather outpost a block or so from CTS that had rainfall data I looked at but WeatherUnderground doesn't seem to want to work for past history anymore; keeps using the airport's data but that's good enough for the 2 days leading up (though 3 days before the collapse the contractor who was there inspecting for pool work stated he saw standing water all over the garage level floor.



Credit to Miami Harold
"The deepest puddle of standing water, according to the contractor, was located around parking spot 78 — an area that building plans show is located directly under the pool deck where in a 2018 inspection report, engineer Frank Morabito had flagged a “major error” in the original design that was allowing water intrusion and causing serious damage to the structural concrete slabs below."

Morabito also took photos of the concrete displacement, hairline cracks, and damaged column base in this area and noted them in his 2018 inspection report. Somewhere around K13.1 Rusted, running stains were also shown on the ceiling.
 
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I figure around 91,424.49 gallons of rain water fell on the structure over those two weeks and that is close to 726,843.4 pounds of dead load. That is roughly 7,724.37 pounds per column. Where did all that water go? Why have there been no reports of 1.94 inches of standing water from any of the eyeball witnesses? Did it all soak into the pool deck? (those are rhetorical questions)

Concrete is not a sponge capable of absorbing unlimited amounts of water no matter how cracked and poorly maintained it is. Even with the poorly designed drains and the flat pool deck, most of it still flowed down those drains or simply evaporated.

Rain water certainly added to the list of reasons for the collapse but calculating the previous weeks rain out to the hundredths of an inch without even trying to determine how long it took to be removed or how much was still there at the time of collapse seems pointless. This building survived 40 years of rain and hurricanes and the last two weeks weather is not going to play a major role.

Stay safe and make sure to hit that subscribe button Folks. You don't want to miss out on all the cool deals that pay my bills.
 
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Demented (Industrial)22 Oct 21 12:00 said:
There was a weather outpost a block or so from CTS that had rainfall data I looked at but WeatherUnderground doesn't seem to want to work for past history anymore;
Click to expand...
I just verified that the second link I provided Maud (Point lake - KFLMIAMI597), works. Scroll to the bottom of the window and then page up to the top of the graph. If one wishes tabular data, click "table".
Surfside Florida - KFLMIAMI583
is another...
 
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Full resolution attached below.
Surfside_Floridays_-_KFLMIAMI583_Summary_june_2021_wwqgtz.png

Full resolution attached below.

SF Charlie
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Layers don't bend in perfect mathematical parallel. Some incipient dishing in the pool slab in those few days will have increased the volume between whatever layers of the slab were delaminating, and allowed more water to pool in the low spots accelerating the process. All in hundredths of an inch for sure but all heading in the same not-good direction.
 
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Cyclic wetting & drying likely also played a part. Wet sand expands slightly compared to dry sand, and many wetting/drying cycles would increase the fatigue of various other deck components. Maybe not much, but such cumulative damage could be the reason why it collapsed now instead of 10 years ago. Just because something survived an event once, twice, or hundreds of times doesn't mean it'll survive the next time. Remember, what doesn't kill you postpones the inevitable!
 
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Eufalconimorph said:
Cyclic wetting & drying likely also played a part. Wet sand expands slightly compared to dry sand, and many wetting/drying cycles would increase the fatigue of various other deck components.
Click to expand...

No.
If the sand is unconstrained and free to expand it can do no damage.
In this case it was constrained by the concrete below it and the pavers above it. You may think the pavers, being weaker than the concrete, would be damaged first. The reality is that the sand would be damaged first. Sand is used to provide a cushion between the concrete and the brittle pavers because it will absorb movement and protect the pavers from damage, whether from moisture or the greater movement of thermal expansion or freezing like we have in more northern areas. The weakest component will always be damaged first.
You can bang your head against a brick wall once, twice, or hundreds of times and the wall will always win.
You are correct that this building collapsed when it did because of cumulative damage, but only from things that actually damaged the structural components.

Stay safe and make sure to hit that subscribe button Folks. You don't want to miss out on all the cool deals that pay my bills.
 
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The pavers were reported to show cracking in that whole area, shortly after the construction next door started with the pile driving. Cyclic wetting & drying of the sand likely did nothing other than being a source of more and then less weight.

Rain, wind, roof work, a heavy impact, vehicles parking on top, vibrations from being a main walk-path from upper parking/front entrance to the pool, construction next door for years, elevators going up and down, lack of rebar, failed waterproofing for various reasons, overtopping of heavy pavers, large bored holes into the slab for the hurricane rated canopy, and column bases in the area getting hit by the assigned parker. It all factored in.

simple_vj7xjr_i7b3on.png

Crappy weather on a night with people coming and going, and heavy water intrusion the days before? I have no doubt in my mind that'd be pretty stressful for a known failed slab that needed full replacement and was to have drop panels installed in the columns to help support the weight. The two previous engineers on the job who were fixing this area missed the issues people on this forum caught within a few days of the collapse

Or a parapet davit anchored to a Trane load testing the newly installed anchors to 5kpsi broke and tilted the PH forward dumping 36 rolls of tar paper onto the deck.
 
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"The update will not provide any conclusions, as the investigation is ongoing, but will introduce a new project that has been added to the investigation, as well as new members of the National Construction Safety Team carrying out this work..................."
Link


Also, although I have yet to see any good evidence that the foundation was a big factor, NIST has greatly expanded that leg of the investigation. 6 of the 7 new hires are geotechnical.

"The new supporting team members are:

Dale Bentz, NIST (Materials Science Project)
Jonathan Bray, University of California, Berkeley (Geotechnical Engineering Project)
Dan Brown, Dan Brown and Associates (Geotechnical Engineering Project)
David Frost, Georgia Tech (Geotechnical Engineering Project)
Larry Olson, Olson Engineering Inc. (Geotechnical Engineering Project)
Dennis Sack, Olson Engineering Inc. (Geotechnical Engineering Project)
George Tamaro, Consultant (Geotechnical Engineering Project)"

Link




 
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