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

 

[drbrainsol]

Quite an incredible collapse for an RC building (if this is what it is). This couldn't have been a single column failing but the whole ground floor somehow. Very strange.

 

[kjm93]

Going frame-by-frame in the video it looks like the failure initiated at the base and over a large area. My guess is a sink hole.

 

[bones206]

Some more perspectives of the adjacent construction. Looks like that building has been completed based on the image posted by JoelTXCive.

 

[Cool_Controls]

you can see the entrance to the parking garage on Google street view.

 

[epoxybot]

If you are the City. what do you tell the occupants of Champlain Towers North & East, of probably the same construction?

 

[rscrane]

Q. from an interested layman with no specific engineering background but some science training:

How do the Search and Rescue crews evaluate safety during operations? Are there steps they can take to rate risk in entering and searching partially collapsed structures, and what would those be?

 

[spinspecdrt]

There appears to be subsiding in the area adjacent the collapse. Look at the cars in the parking area. The depression extends out towards the pool.

 

[Cool_Controls]

I noticed that there appear to be exhaust fans mounted at ground level along the western edge of the parcel are these for an underground parking? (must be a pretty big garage if that is the case)

 

[RickyTickyTavi]

@rscrane

Not me, but my boss volunteered someyears back to be an on-call volunteer structural engineer for fire departments. He would train with them occasionally for building collapses, partial or full, etc. and basically he'd be directed to inform them if they could demolish this wall, or this steel section etc. Where to put up temporary shoring if needed, etc. The risk assessment portion however is valid, and he explained some law (this is hearsay, so im not sure how true this is) that carves out an exception for structural engineering consulting during ongoing rescue operations.

 

[bradw1128]

@rscrane Urban search & rescue teams often have a structures specialist on the team who will evaluate low/medium/high risk, lowest risk entrances to the structure, if/what shoring is needed, etc.

This is probably far more info than you ever wanted, but here is one of the manuals for this role:

http://www.disasterengineer.org/LinkClick.aspx?fileticket=5HuSqoFDvYg=&tabid=57&mid=394

Construction PE (KY)
Bridge Rehab, Coatings, Structural Repair

 

[RickyTickyTavi]

Anecdotal thoughts:

A few years back I worked on a mid-rise condo of the same era and roughly the same height. It had a very scary punching shear failure that was slow enough for residents to notice, report it that day, and for contractors to show up and install shoring posts immediately. Long story short, after a lot of investigation the columns of the condo portion didnt line up with the parking garage below so the original designers put transfer beams between the parking garage portion and the condo portion. The contractor did not put the specified shear reinforcement(and the concrete material breaks were quite low)at the transfer beams and it took 30+ years for a load case for the failure to show.

This is a complete speculation on my part, but it looks like theres a below grade parking garage here and I wonder if the column layout matches the framing above. You can see in the images the columns of the garage have clearly punched through what appears to be the 1st floor slab.

 

[dold]

Re: rescue training, etc - there is a facility in Georgia, US built specifically for the rescue training operations. Perhaps not so much structural assessment, but they definitely practice placing shoring and demolition, etc.

I may or may not have been involved in the construction... .

guardiancenters.com/

 

[Rabbit12]

Good post Ricky. If it was some sort of punching shear failure I'd sure think it would cause a progressive failure like we see in the video.

Tragic, sickening to say the least.

 

[beej67]

Shooting from the hip -

If I had to guess I'd say this was a foundation failure due to subsurface karst topography. Stormwater management in Miami Dade SFWMD is usually done (or at least as of the mid 2000s) with infiltration pipes and baffles into the sandy subsurface aquifer. If the pH of the runoff is low enough, and that dropped the overall pH of the aquifer, it could have dissolved a layer of subsurface limestone and created an underground cave. When karst fails it's a dramatic thing that happens quickly, and that's about all I can think of for this one. The karst theory would fit spinspecdrt's photos too.

Typically SFWMD and the other water management districts prohibit water quality treatment through infiltration in known karst areas, and I don't know if Miami is a highly karst zone or not. I only did one project there, and we did infiltration in our storm sewer network out in the parking lot for it. It was relatively straight forward and we never did any investigations about karst.

I've done a project recently in Nashville where they required us to do infiltration measures for stormwater management even though we vociferously fought them on it because we knew we were on karst. I fear some failures similar to this may be in Nashville's future, whether this one was karst related or not.

edit: Ricky's post above is a great guess too.

edit2: some great rebuttals to this idea are below and I agree it doesn't seem like a karst related thing based on further info in the thread. Disregard, but I'm leaving it up for posterity.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com

 

[spinspecdrt]

beej67, karst related sinkhole was my original thought but as Rimitikitavi pointed out, the columns are still in place and have punched through the deck.

 

[bradw1128]

Sinkhole was one of my first theories having seen some dramatic ones from Central Florida in years past. But from this map that looks unlikely for this part of Florida.

http://fcit.usf.edu/florida/maps/pages/11100/f11165/f11165.htm

I'm wondering about possible impact damage from a vehicle hitting a column in the parking garage.

I also remember staying at a similar condo complex in the Florida panhandle a couple of years ago. There were enclosed storage rooms inside the ground level parking garage where people could stash their beach chairs and pool toys. Inside those rooms was not climate controlled so they were incredibly damp. Anything left in there rusted quickly along with the doors, door frames, and anything else metal. So maybe there could be accelerated corrosion issues in exposed but mostly hidden areas of the parking garage?

Construction PE (KY)
Bridge Rehab, Coatings, Structural Repair

 

[bones206]

I think the punching shear failure seen in the photo could also have been caused by the impact of the collapsing building landing on garage roof slab.

 

[a2mfk]

Just got off the phone with my geologist buddy who is a sinkhole expert, worked with him as a structural engineer for over 8 years all around Florida. South FL geology is very different from Central and N FL geology, so a sinkhole as most know them is very unlikely. We are thinking on the beach there that would be a pile foundation to competent limestone probably 60 feet or more. It is possible that over 40 years some dissolution of that limestone could occur, but the rate is so slow that one would anticipate any settlement of the piles would be very slow and distress in the building would be apparent. The video of the collapse is also not what one would anticipate from a pile foundation failure. (I reserve the right to be completely wrong and surprised.)

The reports are coming in on the roof being worked on and there was a material lift for two weeks on that side of the building. I have evaluated at least two residential roof collapses because of improper staging of roof materials, albeit wood-framed residential, not a multi-story concrete building. But if 40 years of corrosion had affected the reinforcing, then you stage materials on top of that compromised roof slab, this type of failure is entirely possible. The roof repairs could have been to address an unmitigated roof leak, further exacerbating the situation.

I can not tell from the pictures if it is a flat slab with traditional reinforcement or post-tensioned, but we know that PT is vulnerable to catastrophic failure. Corrosion may have affected the ends at multiple floors and balconies. Once the roof slab started to fail it would pull inward on the walls, and the weight and dynamic force of that collapsing onto the upper floor could have caused a chain reaction failure, not that different than the World Trade Center collapses.

Like with most collapses, there are often multiple causes, and this could be one of those.

 

[IRstuff]

But the video does not seem to show a top-down pancaking

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[Umbricus Agathopus]

I saw a picture of cars sitting on a slab that was detached from its supporting columns. If you lose a slab in the parking garage due to punching shear, the column slenderness immediately increases with a commensurate loss of axial capacity. If that capacity is less than demand, gravity will do the rest. Whether the parking garage slabs were overloaded or have been slowly failing for some time until last night the capacity finally dropped below demand is currently unknown. My guess is the parking garage slabs failed in punching shear for some reason and the suddenly (more) slender columns were instantaneously overloaded leading to the collapse.

ETA - from the picture, there weren't drop panels or thickened slabs at the column locations.