Champlain Towers South in Miami has caved in

As with most disasters, I suspect it is the alignment of several situations that, by themselves would not have caused the collapse, but together led to the disaster.

First, the building was build in 1981. This means it was designed using techniques from the late 1970s. No computer design. No computer stress analysis. All done by hand. If anything, IMO, this would have resulted in it being overdesigned, as the computer design systems are much better at minimizing the design based on cost. With manual design, you produce a design, run the calculations to prove it. Repeat as necessary, but the iteration is done by hand on paper and is tine (and money) consuming. It was much more common to overdesign in those days than to optimize for material cost.

This was also a time of a large economic recession. Cheap Chinese steel wasn’t available, but Cheap Japanese steel was. However, at that time, the Japanese structural steel on the market was cheaper and of higher quality than domestic steel (the steel industry was looking for protections from the government). In the 1970s, steel in the US was being made in mills that produced the steel used in World War One (as well as WWII). The design likely was based on the quality of the domestic steel (which had been used for decades and was well understood). In all likelihood, if cheaper steel was used, it would have been of better quality than what the design was based on.

When I was in Engineering School, I had a roommate from West Palm Beach. This was the late 70s. He told me that the construction of condos along the beachfront from Miami north was out of control and since, at that time, had not had a serious hurricane hit Miami in 20 years or so, he expected a lot of those structures to fail when a big one hit. He was wrong. This structure survived 40 years. In the past 20, south Florida has been hit multiple times by severe hurricanes and none of those condos were blown away (including this one).

My bet on the most significant contributing factor is building modifications. Walls being removed or modified, ceilings raised, whatever. Probably within the past two years or so. I suspect that if an unusual event (explosion, enormous party, truck running into the building, whatever) had occurred, at least rumors of such would have hit the internet. That suggests the structure had been failing for some time (like the DeSoto bridge) and the evidence was just being ignored.

If I was 40 years younger with a newly-minted Engineering degree, I would start a Structural Inspection firm. I suspect, in the near future, that business will be pretty good.

Work was being done on the roof of this building (perhaps installing new air conditioning units), but it’s hard to see how that could cause the collapse.

A video of the collapse:

Depends on what equipment was on the roof and where it was positioned.

The second video link is the same as the first, but there’s a half-second at the beginning which shows the video is a security camera playback being recorded onto somebody’s phone.

I was just talking with my wife, who has been watching the news coverage all morning. She mentioned that she had seen some interviews with residents, who had noted that there was another building being built nearby, and that there had been a lot of shaking that could be felt in the collapsed building during that construction. So, that might have been a contributing factor as well.

Miami, collapse, sinkhole was my first thought. We shall see.

As for cheap materials, let me tell a little story. I had an uncle who was an architect. He designed a building and supervised the construction. When he looked at the ticket on the cement mixer he discovered that it was a lower grade cement than he had specified. He asked them to stop pouring immediately and that they blast out the part that had already set. The construction object, “You can’t do that.” “Then I am going to remove my name from the plans and you will never get a certificate of occupancy.” They did it.

It looks like someone ignored Jesus and built his house on sand.

That’s what I thought at first, but @Broomstick made a good argument for why it is relevant.

That was what I first thought of because of that episode of Endeavour where a new housing tower collapsed because too much sand was in the construction cement.

The condo [that collapsed in Surfside on Thursday morning] was going through the 40-year recertification process that is required of South Florida buildings, Local 10 News has learned. The Champlain Towers South building at 8777 Collins Ave. was built in 1981 with 12 stories and more than 130 units. As part of the recertification process mandated after 40 years, the building hires engineers (electrical and structural) and they go through the facility from top to bottom. After the report is analyzed, repair work that was suggested is done. That’s what was happening at this time, with work being done on the roof and elsewhere in the condo, officials say.

Surprising they didn’t see the danger.

Unlikely a natural sinkhole caused the collapse, more likely an unlawful/ unpermitted modification to the building resulted in the collapse.

How terrible!

I too think substitution of cheaper and poorer materials may be the root cause. Or perhaps it was designed and proposed and sold that way. A ‘lowest bidder wins’ situation. That’s possible.

This is like our crumbling infrastructure. Highways and bridges age, even if the design is sound. Buildings too.

Just awful.

Open concept. I want open concept. Tear down those walls! I’d hope they’d have someone inspecting that kind of work, though.

Structural steel, steel rebar, and concrete don’t come in very many grade options; they are a commodity, and all companies that use them use pretty much the same ones. No provider of such materials I have ever worked with, and I’ve worked with a lot of them, bought different grades for different clients or even had much of an opportunity to. The materials that made up the tower would have been the materials commonly used by the fabricators and erectors that did any number of buildings in the area.

A modification is a possible explanation, as well as seismic or groundwater effects on the foundation.

Not to bad mouth inspectors but this is in Miami, where many residents are used to doing things their own way.

Sinkhole was my first thought when I opened the thread. I’ll be curious to see what the actual cause is.

Not all danger is foreseeable.

Is is possible that a natural sinkhole might have started/triggered the collapse?

After all, it doesn’t have to be just one thing that causes a disaster. It could be multi-factorial.

No need to restrict such observations to Miami - there are a lot of places in the world where inspectors might be persuaded to look the other way, where the wealthy are used to doing what they want and ignoring experts, where the poor are neglected. There are many reasons and causes that lead to building collapses.

My Wife watches a program where that is done to improve a house. I wince when they gleefully begin tearing things apart.

Yeah, I hate it! There are a lot of smallish houses in my neighborhood that are selling for well over $1M. I see them on real estate adds and “opening” up the interior makes it look like you’re living in a converted garage – the kitchen is that corner, the living room is that corner, that room with the only door you see? That’s the bathroom.

It says that they were in the process of recertifying the building. It doesn’t say how far along in the process they were. Maybe they just hadn’t gotten to the key part yet in their inspections.

And a sinkhole might be relevant, but that’s not really an excuse. A building that’s built in a place prone to sinkholes should be designed with that in mind, with extra-deep foundations or whatever else you need to mitigate that.