Miami Beach, Champlain Towers South apartment building collapse, Part 02 151

[dik]

thread815-484587


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

-Dik

 

[SocklessJ]

I see a lot of ideas swirling around here, but suggest some of you read up on plaza drainage systems. I see so many plaza drainage system failures due to poor architectural design and/or implementation. This leads to a lot of concrete damage that works it way from the concealed surfaces outward to the visible surfaces.

In my view, you've got a plaza drainage system on an old-school reinforced flat slab system with large planters right next to the point the collapse initiated. This all points to a corrosion induced punching shear failure that took out several perimeter columns and initiated a progressive collapse.

This article from WBDG agrees:
Link

"Harsh exposure conditions from exposure, moisture, thermal effects, weathering, and traffic often reduce these systems serviceability at a rate even surpassing that of parking and bridge deck slabs"

I also found a paper showing reduction in punching shear capacity from corrosion
Link
"The test results show that the corrosion of reinforcement rebar around the column stub in flat slab causes a significant loss in punching shear capacity and affects the structural integrity by increasing crack widths."

 

[Torai]

Miami-Dade Pictometery,

https://gisweb.miamidade.gov/MDCPictometryIPA/pictometry.aspx?lat=25.872848&lon=-80.120845

another county aerial photo site, not the same as DB27 cited. This one has views from top and N, E, S, W oblique views back to 2007. Place marker initially shows on building to the south because it is in the way of North facing view. Top view location OK.

 

[pellucidar]

Miami-Dade Pictometery

If you look at the Dec 2012–April 2013 slice, you can see the pool tile being renovated.

 

[Roga50]

Hello. I'm not a structural/mechanical engineer, but I've been following this thread closely since it started.

I noticed something that may be somewhat of a clue, on one of the real estate listings on Apartments.com from a few months ago. Link

Specifically, there are some pictures taken of the pool deck area. (See pictures 18 & 19 from the top on the above link). Right next to one of the planters, near/above parking spot 78, I see a temporary barricade (see below). What kind of damage was that barricade covering? The watermark on these pictures seems to imply that they were taken around November 2020.

 

[pellucidar]

I suggested some time earlier that the alarm that should have been transmitted to the fire department would have a time stamp. This would then indicate the time for the pool deck collapse.

No survivors have mentioned hearing a fire alarm, have they? Edit 29 of the long Reddit post mentions that there were no flow sensors for the garage level in the plans.

 

[Roga50]

Also on the topic of the water pipe, the plans show that the generator room / fire pump / domestic water pumps were located directly above that entrance. There also is some mention on the upcoming renovation plans of a generator replacement and there is mention of foundation work to be done (but I didn't see any details) to be done to support the new generator. (presumably not started yet?)

 

[spsalso]

replying to nononononono:

Thank you for the contact information.

I am not in a position to build the timeline that I describe. That will be for the government officials who have/need subpoena power.

I was merely pointing out that a timeline of this event will be most interesting. This because there does seem to be a time lag between the collapse of the pool deck and the collapse of the building.

It is natural to think of a structural collapse as being a smooth continuous event that occurs over a short time.

Yet here we see comments suggesting "several minutes" between the first failure and some succeeding failures.

A timeline could describe these delays of failure. And I assure you the reasons for those delays, if they DID happen, will be very interesting.


spsalso

 

[DB27]

Checking the aerials around that date, it looks like there may actually be a hole in the slab at that location.

 

[spsalso]

re: pellucidar's post

buhzillions of dollars to put in a sprinkler system, and no flow sensors to send a fire alarm.

I have indeed led a sheltered life.


spsalso

 

[Torai]

Added 2-Jul: image source is Miami Dade Pictometry top view:

https://gisweb.miamidade.gov/MDCPictometryIPA/pictometry.aspx?lat=25.872848&lon=-80.120845

Original:
Ref the temporary barricade cited by Roga50 1-Jul-21 3:45; a square feature, a black feature and changes (damage?) to the planter border appears adjacent to one of the planters in image of 16-Jan-21

vs no such features appear in the earlier image taken 7-Jan-20 below

 

[TugboatEng]

My parents had a small fire in a lot not far from them. The fire department pulled the water main pressure down and triggers the alarms on adjacent buildings.

 

[DB27]

If the drawings are correct. That looks like the location of the test probe.

 

[Torai]

The “curb” like feature between the planter boxes looks chewed up in the Jan-21 picture, it looked fine in Jan-20.

 

[bones206]

I found this photo of the North Tower pool area. The pavers appear to be the original “keystone” pavers specified on the original finish schedule. Note the lower elevation of the pavers relative to the edge of the pool, then compare to the present day South Tower pavers which were flush with the pool edge. Combined with the test probe callout, I think it may be that the South Tower slab had perhaps double the superimposed dead load that the North Tower has.

North:

South:

The other aspect that jumped out at me is that the waterproofing layer in the test probe was found ABOVE the original paver layer. That suggests waterproofing was added decades after construction, as part of the new paver renovation.

 

[Retiredat46]

In regards to the columns in or adjacent to the planters, does anyone know how the corrosive nature of fertilizers compares to that of salt water? I know both are bad, but I don't know which is worse.

It seems likely that fertilizers would have been used in the planters to some extent over the years, and it could have accelerated the degradation of the steel and concrete in the columns.

 

[lucky555]

"Looked at south/west planter with manager. Planter has structure crack and would need extensive repair manager wants to patch at this time".

permit -02 pg36/178, 09-12-02 (from IEGeezer's links)

This is during major repairs, no change to scope by the Board. Yup, engineers have none of the authority yet all of the responsibility.

 

[warrenslo]

Revised theory after reading this ENR article. The cantilever of roof 2 where roof work was taking place failed and fell into the pool deck slab. Debris also hit the northwest side of the large column in the portion of the building remaining closest to the pool - this column being hit by something (drunk driver thought in the article) is noted in the link below. This in turn caused the pool deck slab to fall (seen in the TikTok.) Then this failure caused the two columns at x611 to fail.

Rolls of roofing paper are still on the remaining building roof. The roof and parapet from roof 2 appear to be near the bottom of the pile under tho column.

The only part I'm not sure of is why the crack in 611 would be starting from the ceiling.

Link

 

[XWD]

Regarding the sprinkler/alarm questions that others have raised: one escapee (presumably from the portion of the building that remained standing) did report hearing alarms, but only after the rest of the building had collapsed.

https://www.washingtonpost.com/nation/2021/06/26/collins-ave-miami-condo-collapse/

Inside the tower, on the fifth floor, Esther Gorfinkel heard something and felt the shaking. Bad weather, she thought. In storm-prone South Florida, shaking didn’t necessarily mean crisis. Then Gorfinkel — at 88, an original resident of Champlain Towers — heard an announcement on the building intercom, first in English, then in Spanish: Evacuate now.

The type of alarm system installed in this building would have used loudspeakers and a pre-recorded evacuation message rather than horns, so this does seem to indicate that the alarm system activated at some point during the collapse, although I have not found any other evidence besides this article. As for why it didn't activate during what appears to be the "initial" collapse (the parking area in the TikTok video), my first thoughts would be that perhaps initiating-circuit wiring between a waterflow sensor and the control panel was damaged during the parking area collapse, or that there was a significant delay in response time from the apparent distance to the nearest waterflow sensor combined with the standard up-to-90-second delay built into the sensor to avoid false alarms from pressure fluctuations.

 

[geotechguy1]

The failure of this building is an engineering problem - pure and simple.

Found this earlier up in the thread.

I wonder how much money has been paid to realtors in the last 40 years to initially sell, and the resell, units in this building, versus how much money was paid for design, inspection, and maintenance - and how much money was paid to the people who had to place the rebar and pour the concrete.

I think we all know where the money is and if you think failures like this are solely a problem of engineering then I think that's a joke.

 

[Roga50]

South Florida has a LOT of work to do...

Link