Not the section by the pool. Just columns. That’s been one of my concerns from the start. There doesn’t appear to be any load transferring structure to the columns at that location. All the columns there just punched through.
I talked about the differences in design within the building in post 612.
to start with you’re quoting someone who remodels bathrooms.
But to your point. there are some beams in the section that collapsed. I talked about how less robust that section of the building was compared to the part that remained standing.
So far, the only indication of the pool deck falling in is by the end of the pool. It did nothing to the section of building that remained. It’s because the deck just slid down the columns in a punch-through sheering action. There’s no lateral movement.
It might be possible that pool deck columns under the rubble collapsed, dragging against the building. but we don’t see that in the section that remained. The columns just punched through.
The forensic study may show other deck pillars collapsed and that pulled against the building. But we don’t see that yet. We do see the garage under the building falling apart and that’s probably the sound described as “walls falling in”. This happened before the deck collapsed.by the pool.
Pool deck collapses, yanks on building supports on that side and the building ever so slowly starts to lean in that direction. As it leans it pulls on the opposite side (the garage ramp side). Concrete and whatnot starts to slowly (minutes “slowly”) crack and fall. Each bit weakens that side and the building accelerates towards collapse. Some big chunks fall down and we see it in the video of the garage ramp. Eventually there simply is not enough structural integrity and it all fails catastrophically.
I should note that I think it is fair to ask if the building should have been able to deal with the pool deck failure and not collapse. Was the building built to cheap standards (the first building with thicker supports survived)? Was the ongoing water problem that seemed a constant issue in the garage weakening the structure?
I dunno. We’ll probably have to wait for the NIST report.
The engineer in my earlier link talked about pillar size and use of beams in the remaining structure. He thought the extra support may have been for hurricane winds. There is also a pass-through lane under that part so I’m thinking it was for that. the extra beams go up 2 levels there.
I’m not discounting your theory but it appears so far that the building that collapsed first was already crumbling in the garage, THEN the pool deck collapses, THEN the building collapses.
They’re all certainly connected to each other because of the amount of energy transferred back and forth in that area.
Personally, I think the columns under the pool deck should have had additional structure elements to handled load transfer. If they had column capitals on them I don’t think it would have collapsed.
As to the beams in the section that collapsed the pictures look like they were cast on to the side of the columns instead of on top of them. that is probably designed to reduce height of the building but doesn’t give any support UNDER the beam.
I still remember working for a company that involved moving heavy production parts. that had fork lift stands so you could drop a part down and reposition it. The beam holding up the item was welded to the side of the column instead of on top. The welds failed and down came the parts. They re-welded the beams on top of the column. I’m sure on paper the original design was supposed to hold the weight but it didn’t. I’d guess it got banged around which weakened the welds. You didn’t have to be an engineer to recognize which setup was stronger.
Now imaging a giant slab of concrete poured into a column with a bit of rebar. The load is attached to the side of the column and not on top. It’s concrete so it’s subjected to the elements affecting concrete. One of them is water. Another would be energy transfer from events nearby.
The site has been cleared. The foundation is in very good condition. No sinkholes or any sign of failure.
Looks like they could build on top of the foundation. They probably won’t because of the collapse and the developer will want a updated architectural design. I’ve seen homes rebuilt after fires. Saves a lot of money reusing the foundation and piers. One ranch house is about the same as another. Make sure the bearing walls sit on the piers.
Where would you dump 22 million pounds of rubble? I can’t imagine how many truckloads that required.
interesting video. the entire pool deck didn’t collapse and they don’t show the sheering of the middle section in steps. If the structure is based on the building plans it will be a good video to walk through slowly to see how it’s laid out in the sub-garage.