Half an apartment building collapsed in Miami last night.

Not saying it's the cause, but Florida (especially central and southern) is what you might literally call not on terribly solid ground.  I believe most of the state was formed as part of an alluvial plane (river output deposits, i.e. deltas)

Overall, Florida's geological history has been driven by changing sea levels, which have influenced the production of carbonate bedrock, siliciclastic input/transport, hydrology, and surface topography. During the last interglacial period, the majority of south Florida was a shallow carbonate environment with some siliciclastic input. Today, we can find massive, fossiliferous shell beds (115,000 years old) throughout inland southwest Florida (Daley 2002). Lake Okeechobee is hypothesized to have been a large river delta that distributed sand, silt, and clay over what would eventually become the Florida Everglades (Petuch 1987).

Margins of the northern Florida Peninsula were also flooded during the last interglacial period. Where the sea level rose thousands of years ago, you can observe today that the Hawthorn Group was eroded away, resulting in a drop in elevation around the Gulf Coastal Lowlands. This is because wave action and fluvial erosion scoured the siliciclastic sediment exposing the carbonate rocks below. The erosional face that we can observe is named the Cody Scarp (figure 8). It is a topographic break of about 100 feet in elevation difference between the Gulf Coastal Lowlands and the Northern Highlands (Katz et al. 1998).

https://edis.ifas.ufl.edu/publication/UW208

BTW: 

Siliciclastic rocks are clastic noncarbonate sedimentary rocks that are almost exclusively silica-bearing, either as forms of quartz or other silicate minerals. All siliciclastic rocks are formed by inorganic processes, or deposited through some mechanical process, such as stream deposits that are subsequently lithified.

bobzilla said:

In reply to Duke :

I saw that this morning. It almost looks like one of those controlled demos without the explosives.

It looks scarily like a controlled demo.  Some nutter is going to be claiming that's what happened

The question you have to ask (not that anyone is actually suggesting it wasn't natural):  How many significant building / structure collapses have you seen that don't look like a controlled demolition?  Why? Because that is how structures collapse when they fail. They are generally very interdependent in design (not sure that is the correct word).  Controlled demolitions take advantage of that, and of course control when and where.

Of course, sometimes that doesn't work out either:

https://www.popularmechanics.com/technology/infrastructure/g2213/10-demolition-fails/

Finishing the demo on some of those had to be "interesting".

aircooled said:

Not saying it's the cause, but Florida (especially central and southern) is what you might literally call not on terribly solid ground.  I believe most of the state was formed as part of an alluvial plane (river output deposits, i.e. deltas)

If you look up the address of the building on Google Maps it's on a strip of land that's less than quarter mile wide with the ocean on one side and a bay on the other.  The building itself is maybe a hundred feet from the beach.

The video is terrifying when you think about it being the middle of the night and an apartment building full of people asleep in bed. :(

I believe it's up to around a 100 missing at this point.

aircooled said:

The question you have to ask (not that anyone is actually suggesting it wasn't natural):  How many significant building / structure collapses have you seen that don't look like a controlled demolition?  Why? Because that is how structures collapse when they fail. They are generally very interdependent in design (not sure that is the correct word).  Controlled demolitions take advantage of that, and of course control when and where.

Consider also that video footage of unplanned building collapses is pretty rare, both because the collapses themselves are rare (really glad of this!) and because nobody knows it's coming so nobody points a camera at it.

The rapid growth of security camers and dashcams has lead to a lot more video of random stuff like this than we used to get.

Duke said:

Security footage from an adjacent property shows the collapse in progress.

 

Sure looks like video's of controlled demolition.   Just sayin'...

If this was a Post-Tensioned reinforced concrete building corrosion of the tension cables could have resulted in a sudden catastrophic failure of multiple cables, like a daisy chain effect of one breaking, then the next, etc, very rapidly .

The  resulting loss of compression in the concrete would have allowed critical concrete to go into into tension. Concrete alone cannot handle tension at all.  Like near Zero.

 This sudden loss of the tension cables would look like a silent implosion. 

A lot of multi-story concrete buildings were build with post tensioning reinforcement to save money and reduce building time.  But the key is keeping the steel cables from corroding.   I bet a lot of older buildings badly need inspection.  I suspect this will be a wake up call. The insurance industry will demand it even if the government drags its feet.   

People marvel that the Pantheon in Rome is a concrete building that has stayed together for almost 2000 years.  What they don't realize is the Roman engineers designed it so all the concrete elements are always in compression.  Like an arch with keystone holding all the stones together with gravity.

For a long time I think we had this idea with asbestos that it was like "eh, no worries. It's fine. It hasn't hurt anybody yet." Then more and more we started seeing the results of just ignoring a potential risk.

I think that's part of our problem with housing and structures throughout the US. We're in such desperate need of housing, but there is so little interest in urban redevelopment. Demolishing an old building is expensive. 

I would imagine the building modern high rise apartments along the Florida cost has become stupid expensive due to improvements in structural engineering and a better understanding of the risks involved, so its "cheaper" to buy something that already exists. I imagine that events like this will spook the insurance industry who will hire more stringent inspectors and we'll see a lot more of these types places get condemned. 

After watching the video I was amazed at the lack of drama. I was trying to see where the failure started but it just is not clear enough.  Sadly the way that building pancaked survival for those in side is not good. 
 

Was the building pre tension or post tension construction?  
 

On a side note this has the potential to eclipse the Hyatt disaster in KC in terms of loss of life. I worked on that in the early 80s and there are still things that I can not un see. I am sure this will be equally as bad. My first job with an engineering company as a sr in highschool and I got tossed in to that. I think I have posted this before here but I keep three of the bolts from the walkway supports on my desk at the office as a reminder as to the consequences of my design decisions. 
 

It really is heartbreaking. 

In reply to dean1484 :

Actually the KC skyways were a shop drawing review issue. Every time I get a protege to train I tell them "Shop drawings are complicated, tedious, and missing a single note can cost tens of thousands of dollars, or worse."

Duke said:

In reply to dean1484 :

Actually the KC skyways were a shop drawing review issue. Every time I get a protege to train I tell them "Shop drawings are complicated, tedious, and missing a single note can cost tens of thousands of dollars, or worse."

Trust me I know exactly the what and why on that one.  The original design was ok but field changes and subsequent poor review of the proposed design changes lead to the failure.  Had the rods been single pieces as originally designed it probably would not have happened. And I say probibly because there were issues discovered with the original design as well but those were not really relevant as that was not what was in place so it was deemed inadmissible although the prosecutors disagreed and I can see why. 
 

One of my jobs was to sort out what photos were released to the public and what was kept "in the file". I honestly think I got that job because I was the low man on the team if you could even call me that. These were raw un edited photos taken directly after the disaster and throughout the removal process. It was such a weird experience to see photos marked up for technical notes by the engineers / investigators with no comment on the other "stuff". You get desensitized quickly as there were many thousands of photos to go through and at some point I realized I could not afford to get emotionally involved. I looked at it as I was protecting the dignity of those that died and was protecting their families from even more grief and hurt.  

In reply to dean1484 :

Ugh, that was just a nightmare all around.  IIRC the as designed setup was not physically possible to build because it would have needed two or three walkways threaded through the same rods, so they went with the...  bodge.

I've read a lot about it and seen a few documentaries and everything about it, from the changes made without engineering review to the rescue operations afterwards, was absolutely horrifying.  I can't imagine the things you've seen that have been kept from the public.

aircooled said:

Not sing it's the cause, but Florida (especially central and southern) is what you might literally call not on terribly solid ground. 

So, it was daft to build an apartment block there?

The security camera footage of it going down is crazy to watch! 

dean1484 said:

Duke said:

In reply to dean1484 :

Actually the KC skyways were a shop drawing review issue. Every time I get a protege to train I tell them "Shop drawings are complicated, tedious, and missing a single note can cost tens of thousands of dollars, or worse."

Trust me I know exactly the what and why on that one.  The original design was ok but field changes and subsequent poor review of the proposed design changes lead to the failure. 

The FIU pedestrian bridge was a similar thing.  A former gf had a best friend die in that one.

In reply to dean1484 :

I've never thought about the exposure of such horrible things to engineers after a disaster or catastrophic failure. I was the arresting officer in a double homicide back in 2002 that involved the dismemberment of the victims and the perps performed sexual acts with the bodies of the victims while dismembering them. They took 284 photos and 8 videos while doing so. It damaged me. Despite knowing that the odds were that I'd have stumble upon another case like that (I was a plain clothes narcotics officer, not even a homicide detective) I resigned. For a period of time I assumed the worst in people and I knew I could not be an effective officer if that were the case. I think that I've only talked about it with a half dozen people or so. There are still certain images permanently engrained in my memory. 

I've never even considered that engineers are exposed to horrors of a similar degree and have a new found compassion, as I was ignorant to that necessary evil. 

The NYT reported this morning, 4 confirmed dead, 159 unaccounted for.

In reply to captdownshift (Forum Supporter) :

This is really the first time I have elaborated on it publicly. It changed me for sure.  I had technicolor dreams for years after that but eventually I made a personal peace with it. It definitly has impacted my approach to my profession. 
 

However what you are describing is a whole next level of mind melting E36 M3.   At some point the brain shuts down and stops processing.  
 

I don't think the average person understands (or cares to even know about) this kind of stuff. 
 

It certainly was not what I thought I was signing up for with that job/profession but it is part of it.  Another one is Lawyers. Say what you will about them but the E36 M3 they see is just not fathomable. 

In reply to dean1484 :

The most alarming words that sting me to this day is what the D.A. said to me while we were reviewing evidence one evening months before the case. She turned to me and asked, "Dave, have you ever made a sex tape?" I was taken back. She assured me that she was asking for professionals purposes as a matter of perspective and realization. I answered honestly, that I had not (this was 2002, cell phone cameras were fairly new and 0.3 MP and video from them looked like a scrambled cable box). She replied with, has it ever crossed your mind to though, have you considered it? Again, I answered honestly, that I had, but hadn't done an beyond passive consideration. That's when the question turned. She asked if it was something that I even considered when I lost my virginity. Before I could even respond, she was highlighting a realization that I had not made. People don't video or photography themselves taking part in such acts the first time they do them. It's not until they're comfortable, confident and know that they enjoy it and take pride in it. 

Sorry about the sidebar. Back to the regularly scheduled gruesome reality. 

In reply to captdownshift (Forum Supporter) :

Whoa. That's an angle that I would not understand unless explained.

I agree this is some kind of human error. The architect. The structural engineer. The contractor who may have read the plans wrong. The building owner who ignored the signs that serious repair was needed. 

There had to be some reason why this particular building was sinking and the others around it were not. 

There are stories coming out about creaking noises, cracks, leaks and mold issues. All of which may point to earlier damage leading to more damage. 

In the last 40 years how many hurricanes have hit the area? Tropical storms? I can't imagine any structure in that environment holds up well for that long. I know we as humans like to think what we make is forever and indestructible. Mother Nature says otherwise. 
 

none of this makes it any easier for the families waiting for word on their loved ones. I've become pretty heartless over the years in regards to humanity but I do feel for the families. 

In reply to captdownshift (Forum Supporter) :

Wow, so to extrapolate, the most sick, depraved thing most people can think of, somebody somewhere is doing it for lunch, or for E36 M3's and giggles.  Puts horror movies in an new light for me.  Humans are messy at best, and downright frightening at their worst... Thanks cap'n...    

EDIT: Back on topic, at least one local newspaper is speculating about the influence of King tides on the area https://www.palmbeachpost.com/story/weather/2021/06/25/could-climate-change-have-contributed-surfside-condo-collapse/7779816002/

From my experience things like this happen because of multiple combined factors. There is very rarely a single smoking gun.   There are many theory's being batted around but I suspect that it will end up being a combination of things that caused this.  
 

There is a real possibility that we never find out for sure what happened. The forces in play in a collapsed like this are huge. The failed components of the building could be dust.  This unfortunately happens to humans in the building as well. 
 

I hope someone has the forethought to see  if there are other buildings designed and constructed by the same entity's and be inspecting them as well for possible clues.  Or to avert a repeat. 

Apparently there is some suspicion now that the crap ground that makes up south Florida might have a part in it:

https://www.wfla.com/news/florida/ground-under-collapsed-florida-condo-had-been-shifting-since-1990s-geologist-says/

bobzilla said:

In the last 40 years how many hurricanes have hit the area? Tropical storms?...
 

What Bobzilla is trying to say here ():  Is that nature does not want people to live in central and south Florida.  It has been making that pretty clear for a number of years now!

I am also thinking there is likely some sort of native curse going on:

An estimated 3,000 Seminole and 800 Black Seminole were forcibly exiled to Indian Territory west of the Mississippi, where they were settled on the Creek reservation. After later skirmishes in the Third Seminole War (1855 -1858), perhaps 200 survivors retreated deep into the Everglades to land unwanted by settlers, where they were left to live.

https://en.wikipedia.org/wiki/Seminole

Hey, if you where forced to move to Mississippi, you would be pissed to!