Miami Beach, Champlain Towers South apartment building collapse 151

[bugbus]

Partial collapse of 12 storey apartment building in Miami Beach:

https://www.google.com.au/amp/s/

http://www.dailymail.co.uk/news/art...-building-collapses-sparking-huge-search.html

Was built in 1981. Not much information as yet.

Building profile:

https://www.miamiresidence.com/surfside/champlain-towers.htm

 

[epoxybot]

One way or another, you can bet the City of Surfside & the developer of the newer property next door are going to be dragged into whatever legal wranglings arrise. There used to be a public street/parking lot for beach access between the two properties. Now there is just a walkway for beach access, with the remainder of the former street providing a trash enclosure, landscaping and some other enclosure. I assume below all of this is underground parking. Surfside also has a parking lot for beach-goers across the street.

 

[jrs87]

clean rebar

Perhaps the unzipping occurred at a very high velocity. The unzipping was secondary to the collapse, as corroded bar would not unzip like this.

 

[DavPc]

A lot to unpack here...

Someone should investigate whether (in an attempt to appease today's multi-vehicle families) the parking structure was reconfigured from the original layout to pack more vehicles in, exceeding the original design's specs.

Even if it wasn't changed I have to believe the load on the parking deck was more than it was in 1981, despite some cars being lighter. The number of crossovers, SUVs, and pickups owned today cancels out any weight improvements in sedans and other small cars. And that doesn't even take into account electric cars, which are a lot heavier than their 1980's counterparts.

The timing of the collapse is interesting. Do bars still close at 1AM like they did when I lived down their in the 70's and 80's? As suggested earlier in this thread, it wouldn't be much of a stretch of the imagination to think that someone who had too much to drink mistook the accelerator for the brake pedal and plowed into a column, dropping the already weak deck above them and causing a cascading failure due to all the other problems this building had. Was there CCTV coverage of the garage and did the server survive? Regardless of what triggered the collapse, that would be some interesting footage indeed.

A column being taken out under the pool deck could explain the "sinking" that was reported just before the collapse. If it turns out it did start under the pool deck, it's criminal a part of the structure that has no bearing on the rest of the building could "tug" enough on the columns where the collapse occurred, causing them to snap in half and causing a catastrophic drop of the deck under that part of the building - and as has been speculated already - the lack of lateral support causing a cascade event of columns buckling.

I'm shocked by how easily the deck sheared from the columns and how cleanly the column rebar pulled out of the deck in the section where the building managed to remain standing. Those residents are extremely lucky - the only thing that saved them was the parking deck cleaving cleanly from itself, leaving the rest of the deck aloft to provide the necessary lateral bracing.

The piss-poor rebar placement is just as shocking. Perhaps someone thought because Florida doesn't have earthquakes the possibility of rebar unzipping from the bottom of the deck was highly unlikely? Perhaps even thinking the more concrete above the rebar made the rebar less likely to unzip from the top of the deck where it mostly mattered? I suppose the most likely reason for what we are seeing is a rushed construction schedule which prevented workers from properly positioning the rebar in the middle as it should be.

The building seemed top-heavy to me, especially from the slow twisting path the last section took during its fall. There's no excuse for that section to remain standing and then fall soon after. A building should be able to stand even if an entire row of columns is compromised. It's interesting the part that fell had a penthouse addition added after the initial design. It also doesn't help non-structural concrete block was used as sound and fireproofing. That's a lot of extra dead weight the structure had to carry.

And finally it's being revealed the building actually did have major structural issues that needed to be fixed, which only compounded all the issues (and possible issues) above. It is unfortunate it was procrastinated upon for 3 years until it was too late.

 

[hetgen]

Question for the SEs: i've got a "can you design this building like this under todays codes?" question.... Specifically, can the stair tower in the far wing NOT be designed with just 1 shear wall?

No, you can not! The structure doesn't have sufficient shear walls parallel to the numeric grid.

The design wind load for buildings located on the coastline is very high. Note, I'm not saying that is the cause of the collapse, but the drawing shows only two 8ft long shear walls to fend off a high-velocity hurricane zones wind pressure x the building area facing the ocean(150ft x 117ft)? You can't make this work.

 

[Kreemerz]

@Jrs87
Why are you calling me a troll?

What's that all about?

Dik mentioned that there was a report in 2018 that mentions 'structural damage'. As a Californian, I usually only hear of structural damage caused by seismic activity.

How do I reply with a quote? Maybe that's why @jrs87 is not clear on my question.

 

[waross]

I wonder if the construction crew was primarily from Central America.
During my time in Central America I observed the following construction sequence many times.
1: Low slump is your enemy. Concrete was typically mixed with almost no very high slump so as to be easy to place.(Corrected)
2: Re-bar is often laid directly on the forms for elevated floor slabs.
The wet mix leaves the concrete very porous.
Moisture attacks the re-bar and corrodes it.
Iron oxide has more volume than the original iron, and the expansion due to corrosion blows the concrete from the re-bar.
A common sight in older buildings is a concrete ceiling with the re-bar grid exposed and rusty.
A friend of mine was having a new house built. The design called for a cantilevered shade deck over the entrance to the garage.
When the contractor started to remove the forms, the deck started to subside.He tied it back to a parapet wall with cables and turnbuckles.
I was asked to look at it. I remarked that an overhung deck would not be supported by rebar lying on the bottom form. The re-bar must be higher in the slab to be effective.
The owner talked to the engineer and reported back to me:
"The engineer says that the re-bar must be on the bottom to keep the concrete from falling."
Without close supervision, a crew with southern experience will tend to revert to the way that they were originally taught, which is also easier.
I would suggest that the lower the wages, the more supervision is needed and the more suspect will be the concrete quality and the correct placement of the re-bar.

My favorite for the all time worst re-bar placement was a narrow roadway up a side hill.
The roadway was graded and the re-bar was laid directly on the ground. Then construction traffic ran over the re-bar for a week or so.
Then the concrete was poured with no attempt to lift the re-bar up out of the dirt.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[Ingenuity]

Concrete was typically mixed with almost no slump so as to be easy to place.

'No slump' concrete is very difficult to place - I think you mean high slump concrete - like 8"+ slump.

With today's admixture technology, concrete with a large slump can be ready-mixed without reduction in strength nor durability - not so much in the 'evil-80's'.

 

[TheGreenLama]

"FEMA was ready to deploy to the condo collapse almost immediately, and included the crisis in its daily briefing, but didn't get permission from Gov. DeSantis to get on the ground for a full day." source Link

 

[jrs87]

Kreemerz, no offense was meant, I assure you. I asked if that was your intent, that is different than calling you one.

There is a toolbar with icons in the editor that help you form your post. The term "Good grief..." in this neck of the woods is sometimes pejorative and mocking.

Hope, we are past this now with no worries and back to the subject.

P.S. Corrosion is form of energy like seismic activity. So corrosion plus gravity equals structural damage. Right?

 

[799931]

The planted column Ingenuity pointed out is interesting, it seems like it would take a few structrual irregularities like this to fail in order to bring a stucture down so quickly.

Would be interesting to see if any of the damage/corrosion from the 2018 report affected any elements in that area.

This still just so hard to believe, I would expect more load redistrubtion and large displacements before full collapse on a RC structure (even if the engineering/construction is suspect).

 

[Keith_1]

Slump tests are extremely important, because it is the only to know if the aggregate is incorporated. Plasticizers are necessary to make hot mixes both deliverable and workable.

 

[Mark R]

Here's an interesting post from YouTube, it's the initial fire department radio traffic from the initial response. How cool the responding units are is truly impressive.
https://www.youtube.com/watch?v=YZNvgcLUnls] Miami FD communications [/url]

 

[SFCharlie]

Help. Has anyone been able to find the plans for the new penthouse and replacement AC unit? Thanks.

SF Charlie
Eng-Tips.com Forum Policies

 

[thebard3]

Why are you calling me a troll?

Welcome to the board. Don't be disheartened. I was slammed hard for my very first post a few years ago. We have some spirited discussions here.

Brad Waybright

The more you know, the more you know you don't know.

 

[jrs87]

Yes, welcome Kreemerz

Focus shifting to long term pool leak.

https://www.dailymail.co.uk/news/ar...mage-damning-report-three-years-collapse.html

 

[pellucidar]

Here's a reddit thread with extensive details of the camera, witness, and survivor locations within the building: /r/CatastrophicFailure.

 

[SFCharlie]

Thanks for the photos. I know what it takes to dig these out.
To me, it looks as if they not only replaced the AC, but also changed it's location???

SF Charlie
Eng-Tips.com Forum Policies

 

[IEGeezer]

From 8777-collins-ave---unverified-inspection-report:

https://www.townofsurfsidefl.gov/do...ified-inspection-report.pdf?sfvrsn=8c2a1194_2

Inspection done between 8/01 and 9/06/2018:

"2.Settlement: Good – no building settlement observed"

 

[jrs87]

The city's major concern was interior lighting being bad for turtles at the seashore. (reddit)

 

[dik]

According to this report, there is nothing wrong...

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

-Dik