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> On the other hand columns fail by buckling when they become too slender…which is effectively what happens when a column loses steel and concrete due to corros

> On the other hand columns fail by buckling when they become too slender…which is effectively what happens when a column loses steel and concrete due to corrosion and spalling. Okay, great. So you're clearly more qualified than I. The above fits with my understanding too. I haven't seen reports that the columns in question were losing dangerous amounts of steel or concrete. Here is the picture from the 2018 report. Is this collapse-level amounts of spalling? https://static01.nyt.com/images/2021/06/27/world/27miami-mystery-peint2/merlin_189909303_139af962-9c01-465a-b71d-36b4591ae91f-jumbo.jpg https://static01.nyt.com/images/2021/06/27/world/27miami-mys... These are 2018 pictures, it could have certainly gotten worse. Enough to threaten the building in 3 years? There were contractors and engineers bidding on the work for the upcoming 40-year maintenance. Would damage sufficient to threaten the building be obvious at a glance, or would that need testing and detailed analysis? > The only unusual aspect is that it is the first. But Florida has buildings with similar issues down one side, up the other, and around the Big Bend all the way to Alabama. This doesn't surprise me, unfortunately.

brudgers 5y ago
See all that fairly fresh paint? In the first picture they painted over failed concrete. The pictures are said to be “typical.” The reasons it wasn’t evacuated at the time were business and politics not comprehensive structural investigation. You see if the client isn’t paying to find problems below the surface, then they won’t be found. And it is common for clients to not want to find such problems. And for engineers to limit their analysis accordingly. I know what my professional opinion would have been based on those pictures. It would not have been good for my business given the client profile. Or to put it another way, those pictures show that what happened had a real chance of happening. That’s not hindsight. It would have caused me grave concerns.
- MertsA 5y ago
  Yeah that's some pretty widespread spalling on the garage deck. Regardless of what went wrong, I'd be surprised if rust jacking or just plain section loss of the rebar wasn't a principle factor behind the collapse. All of that rebar has just been rusting for an additional 3 years since those photos were taken and it looks like the corrosion was already pretty spread out at the time and no one did anything to address it. Tyler Ley has dozens of videos on the topic, I know I've seen a great overview of concrete deterioration but he's got so many videos I can't find it. Here's a intro to concrete corrosion though that explains some of it. https://www.youtube.com/watch?v=mOCJFCaXN0s https://www.youtube.com/watch?v=mOCJFCaXN0s
  - secabeen 5y ago
    Thanks to both of you; this is better analysis than I've seen in other forums.
    - brudgers 5y ago
      Conversely, your response to my initial comment was internet ordinary.

brudgers 5y ago

See all that fairly fresh paint? In the first picture they painted over failed concrete. The pictures are said to be “typical.” The reasons it wasn’t evacuated at the time were business and politics not comprehensive structural investigation. You see if the client isn’t paying to find problems below the surface, then they won’t be found. And it is common for clients to not want to find such problems. And for engineers to limit their analysis accordingly. I know what my professional opinion would have been based on those pictures. It would not have been good for my business given the client profile. Or to put it another way, those pictures show that what happened had a real chance of happening. That’s not hindsight. It would have caused me grave concerns.

MertsA 5y ago
Yeah that's some pretty widespread spalling on the garage deck. Regardless of what went wrong, I'd be surprised if rust jacking or just plain section loss of the rebar wasn't a principle factor behind the collapse. All of that rebar has just been rusting for an additional 3 years since those photos were taken and it looks like the corrosion was already pretty spread out at the time and no one did anything to address it. Tyler Ley has dozens of videos on the topic, I know I've seen a great overview of concrete deterioration but he's got so many videos I can't find it. Here's a intro to concrete corrosion though that explains some of it. https://www.youtube.com/watch?v=mOCJFCaXN0s https://www.youtube.com/watch?v=mOCJFCaXN0s
- secabeen 5y ago
  Thanks to both of you; this is better analysis than I've seen in other forums.
  - brudgers 5y ago
    Conversely, your response to my initial comment was internet ordinary.