Well the original design would have been very difficult and expensive to fabricate. You can’t just thread the middle of those long support rods that the skybridge was hung from. They would have had to be custom hot forged with a thicker section in the middle to have the threads cut into it, or been machined down across half their length to a diameter thinner than the grooves that make up the threads. Either one would have been impractical. That is why it was changed. So I wouldn’t describe it as “fine.”
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It’s not impossible for that to be the case as your example shows. It’s just that the longer the building stands, the less likely it is that you can trace that failure back to the initial design to the degree of certainty required in a courtroom to assign blame.
This building stood for 40 years before it collapsed. A lot of small things over the years could have contributed to the failure. I think one interesting bit I heard in an interview was how the basement of the building was completely flooded. I’m guessing the Sandy beach soil beneath the building was experiencing liquefaction and could no longer support the load.
SC - who lives on top of a liquefaction zone at the beach in LA.
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One of the pictures of the responders had a “Collapse Unit” vehicle in the background. Does this happen often enough to warrant this or is the Miami infrastructure just so large that specialized response units exist?
Concrete not properly prestressed?
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I’m thinking your guess could be correct, based on the way that it collapsed. At first, I thought it might be a post-tensioned cable concrete building failure, but the fact that the middle of the building appeared to fall down first makes me think that part of the structure was sufficiently undermined that it gave way and the rest followed.
Heavy equipment on the roof plus whatever work the heavy equipment was on the roof to do seem like, at least, contributing factors. Its what caused the I-35W bridge collapse here in Minneapolis several years ago. Poor maintenance and changing conditions of the underlying load bearing ground are probably also factors. In any case where the questions “was it this or that” is asked, its usually a combination of both or all.
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Doesn’t the rebar in concrete sometimes rust and damage concrete over time because rust expands?
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That sounds like a very plausible explanation. I wonder if they got any warnings? eg, cracks in the basement. And, just how fast it transformed from a minor risk to imminent risk of collapse.
Im no expert but that’s a risk level approximately akin to placing the foundation on a known native american burial site.
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“A researcher at Florida International University said the building was constructed on reclaimed wetlands and was determined to be unstable a year ago.”
“The building was sinking at a rate of about 2 millimeters a year in the 1990s, and the sinking could have slowed or accelerated in the time since, according to a 2020 study conducted by Shimon Wdowinski, a professor in the Department of Earth and Environment at Florida International University.”
Well, fuck. Seems like we’ll be seeing a lot more of these kinds of collapses, then, because Florida is full of former wetlands, sinkholes and climate change causing groundwater issues.
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On the one hand, it’s too early to speculate. Focus on rescuing the missing individuals.
otoh:
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I remember Robert Evans talking about, after the Beirut fertilizer explosion, how we will start seeing a lot more of these disasters in the near future. Both nobody and everybody to blame, symptoms of the he systems around us disintegrating.
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Given the size of the Miami metro and the frequency of hurricanes it is probably a pretty basic response team.
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And not just systems disintegrating - but systems being actively neglected, if not dismantled, by free-market fuckwits to whom any regulation is an outrageous restriction on their freedom to exploit for money anyone and anything and damn the consequences.
Until the uneducated dickheads who believe those fuckwits realise that society is a thing and a civil society has a shared cost, there will indeed be more of these disasters in the near future.
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There were reports (and at least one lawsuit) of cracks and leaks in recent years.
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I have a theory about this. Our (well, my, anyway) grandparents’ generation built a fairly miraculous infrastructure during the post-WWII economic boom, and bequeathed it to our parents and to us. Like many types of inherited wealth, we treated it as an entitlement rather than a responsibility and refused to invest in the upkeep and updating so necessary for these sorts of things, then act shocked when it starts falling apart. “It’s not our fault! We can’t afford to maintain these!” makes me think of the old truism “A stitch in time saves nine.” We certainly can afford to maintain it, it would just slightly cut into the profitability of our current usage. I mean, literally, “You didn’t build this,” but you were given it for free, just need to maintain it. No can do, bucko, gotta get those bucks. 
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Good theory. Plus, new infrastructure today is never built for the prime purpose of public service, but for private profit. Which means cheapest cost, corners cut, etc. Even apparently public expenditure is prioritised to be spent with private providers whose interests (and donations) most align with the power-holders, rather than with the most benefit to the public.
When stuff is built for public service, the public purse, just like anyone’s, ought to consider value and lifetime - as well as maintenance - not just cost today. But cost today and low taxes with maximised private profit are all that matter. Sigh.
Bucks which will be in short supply when rebuilding is needed at a cost of many times what the maintenance would have cost.
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that npr link someone else posted above mentions the unit normally responds internationally. i can only imagine it’s unusual that they’re responding where they’re stationed. most us buildings don’t spontaneously collapse.
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This can be an issue with publicly funded structures as well. Every politician wants to be photographed cutting the ribbon on a new project. But to maintain the stuff built by the previous guy? Not so much.
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sandcastles in the sky
FEMA has such teams. Did it say Miami on the side or could it be part of the FEMA response?
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