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Miami Beach, Champlain Towers South apartment building collapse 151

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The typical building foundation in this region consists of grouted friction piles and grade beams. Underground parking structures with transfer beams are basically par for the course. What I can not wrap my head around is how a building can have such a catastrophic failure without anyone noticing the obvious signs.

The only thing that I can plausibly imagine is that a major transfer beam failed, which overloaded adjacent columns -- leading to a cascading failure.

In this region moments from seismic events are not an issue, our biggest challenge is protecting the buildings envelope from wind loading, especially negative pressure.
 
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Dating back to 1980s, what were the disproportionate collapse requirements like back then over there?

A truly horrific event.
 
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Latest news says four confirmed dead and 159 missing. Absolutely tragic.
 
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One news source has said there may have been concrete restoration ongoing - thinking if they chipped too much or more than one column at once without proper shoring, combined with the "weak story" in the lobby where it is likely columns shifted locations....
So sad and tragic that I can't wrap my head around how a failure like this happens..

This picture just makes my jaw drop and my heart sink:
 
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How much concern should there be about the remaining structure? I’m not a structural guy but it seems that floor diaphragm might be kind of important as it pertains to those columns.

It seems like if any sort of forensics is going to be done the cleanup and recovery will have to be done in a very controlled fashion. Will they have to bring that part of the building down before they can start to clean all of this up?

Where does this spontaneous (for the moment) collapse disaster rank in the US? And worldwide?

Tragic.
 
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Has anyone ever seen a design where a single point of failure leads to this? I sure have not. Spalling decks, columns, sheer walls and beams, along with PT wedge failures on bonded PT are pretty common in buildings of this type and era in the region. It is really not a big deal in terms of life safety, simply because the signs of distress are pretty obvious, and remediation of the various conditions is pretty straight forward.

I really am doubtful of subsidence, simply because a mat foundation with piers is not very common on oceanfront construction at that NGVD or NAVD elevation. The sheet piles for the underground parking and the associated dewatering is tough enough,
 
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Another data point:

One of the residents claims he noticed pool patio pavers cracking during the construction of the adjacent high rise building.

Cohen said he raised concerns years ago about whether nearby construction might be causing damage to the building after seeing cracked pavers on the pool deck.
Click to expand...

Source:
 
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"Has anyone ever seen a design where a single point of failure leads to this?" - Keith 1
Ronan Point Apartment Tower
Alfred P. Murrah Federal Building - ref. Oklahoma City Bombing

In this case, I don't think it is wild speculation to hypothesize that long term settlement overstressed and led to the failure of a 2-way floor slab to column connection. This doubled the bracing length of this column which then exceeded its axial capacity and failed suddenly under buckling. The other hypothesis would be a failure at a column to transfer beam connection.

Questions to investigate - what is the detailing of the 2 way slab to column connection? Photos only evidence top horizontal rebar
What was the geometry of the parking grid columns to apartment grid columns?
Did the building really settle 3" and was that settlement discrete or overall?

I think its important to recognize that the reason for our attention on this disaster is due mostly to the lessons that we, as engineers, learn from failures. A failure that occurs suddenly 40 years after a building's construction, especially if it was properly detailed and built, is something to be identified and corrected for the sake of the rest of our buildings' catalog.
 
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@Spartan5 I'm actually concerned about the columns supporting the remaining mid-rise. Their unbraced length has doubled due to the ground floor slab falling down. Thats can be a significant drop in axial and bending capacity for a column.
 
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ongoing settlement over decades certainly seems related to the problem. Seems a, "pop-type" failure, for sure.

Live load considerations?

Shoreline rebar deterioration and or inadequate cover from the onset.

Such a catastrophe!

f-d

ípapß gordo ainÆt no madre flaca!
 
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Teguci said:
I think its important to recognize that the reason for our attention on this disaster is due mostly to the lessons that we, as engineers, learn from failures. A failure that occurs suddenly 40 years after a building's construction, especially if it was properly detailed and built, is something to be identified and corrected for the sake of the rest of our buildings' catalog.
Click to expand...

As I just learned (and shared the link above), the instigating event behind Miami's 40 year recertification process was the collapse of the Miami DEA building in 1974, which was 40 years old at the time. The Miami-Dade engineer behind the effort saw the particular vulnerabilities of aging structures in the area, and was determined to create a process that would help prevent future collapses.
 
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My wild-ass guesses (WAGs):

Long-term settlement caused cracks in concrete, allowing saltwater access to the reinforcing rebar, and increased stresses on connections.

Vibration from nearby construction (and general use) worsened fatigue.

Roof work increased live load.

One of the basement connections eventually failed, and the whole thing pancaked.

Obviously there are lots of open questions. Was the settlement due to sea-level rise unaccounted for at the time of construction? What was the immediate cause of the collapse? Are any of the WAGs even true, or was it something else like a sinkhole? What code or enforcement changes could prevent this? How many other buildings in the area are at similar risk?
 
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Just a question for the SE types here, but has there been any change or increase in live load or dead load for parking structures due to the fact that cars seem to get bigger and heavier with every decade?

I wondering if there is a gradual effect a bit like the increase in "average" passenger weight that they use for aircraft has needed to be updated as the population got bigger and heavier??

A little of googling finds the average weight of a car in the 1980s was about 3,000 lbs and is now over 4,000 lbs.

Given the residents of the block are probably in the higher percentile earning group are likely to have bigger cars than the general population??
Could you be talking double the weight compared to what was assumed in 1980?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 
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That's a 1.25x increase in weight, but aren't design loads for 3x+? And I don't think I could buy in to the theory all of the cars (on the top garage floor) were up-sized... maybe 25-50%? I'm not sure I buy the average weight of a car being 4k pounds, either... there may be a number of large vehicles that hit that weight (SUVs and the like), but plenty of others are well below the 3k mark (your average mid-size is probably in the high-2k range).

Dan - Owner
Footwell%20Animation%20Tiny.gif
 
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LittleInch said:
Just a question for the SE types here, but has there been any change or increase in live load or dead load for parking structures due to the fact that cars seem to get bigger and heavier with every decade?
Click to expand...

Before IBC 2006 I believe parking garages were 50 psf. Now they are 40 psf.

Average car length is like 14-15 feet x 6' wide. Cars this size weight less than 3000 pounds. 40 psf gets you 3360 that's assuming cars are packed like sardines. With the drive aisles spaces between cars, etc. 40 psf is pretty conservative in most parking garages.

RC


 
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bones206,

Maybe they should make it every 30 years?

Good Luck,
Latexman
 
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