Reply #112: Well, it's not that odd to a lot of other people

[anigbrowl]

I posted a video downthread of what happens to a steel-framed building (as opposed to a concrete one) during demolition, showing how substantial deformation can occur. This, in a butshell, is why the top of the tower began falling apart in mid-air.

However, even with it crumbling and ejecting lots of dust and pieces, you're still talking about a massive amount of weight falling onto the rest of the building after structural integrity has been lost. The top part of the building does not need to have all its structural integrity to be a crushing weight.

As a simply analogy, imagine a breeze block and the equivalent weight of gravel. Obviously the breeze block has structural integrity whereas the gravel is just a bunch of loose stones. But if yo drop both of them from the same height, they'll hit with ground with equivalent force, because you have the same amount of mass accelerated by the same gravity.

The distribution of the force at the point of impact will be different, for obvious reasons, but if the force is sufficiently large it will still crush whatever is underneath it.