A marginally related question.
There were a couple of buildings in the WTC complex which weren't hit, didn't burn, and also collapsed. One of them was a 47 story structure.
Why did those collapse? I looked, couldn't find why.
Don't know why anyone would want to build bigger. At least not taller. Couldn't rent them any more, at least for a while. I read reports saying that the Sears Tower, Transamerica Tower and Empire State Buildings were having a difficult time attracting rentors.
I wouldn't live or work in one of them. Probably an overreaction, I was nervous in a building that tall before 9-11.
Arf