[Mod note: thread split from https://www.metabunk.org/how-buckli...ation-for-part-of-wtc7s-collapse.t8270/page-4, some posts have been merged or deleted to simplify the flow of the discussion] The problem with building 7's free fall is that nobody was stepping on it like a soda can, and there's no way to hollow out the middle of the building quietly and without causing extensive damage to the outside. Before it fell, there were a handful of broken windows, that's it. Pretty much the whole building fell as one, and did so at free fall acceleration for a period of over 2 seconds. Can't be reconciled with collapse by fire. The NIST account doesn't even approach reality. We can all disparage crazy conspiracy theories, but the official account doesn't stand up. I'm talking about the lack of damage to the exterior caused by the supposedly-falling interior, not damage that happened 7 hours before collapse. The idea that free fall buckling is possible, the claim of this thread, depends on the exterior being like the wall of a soda can. That means that it has to be a thin tube, the only structure remaining after the building gets hollowed out. We can see that this view is false, because it is not possible for the middle of the building to hollow itself out, leaving just a few broken windows on the exterior. The NIST account wants us to believe that after column 79 failed, a sequence of floor failures traveled right to the top of the building, and then column failures propagated west, as falling girders took out beams and girders next to them on the way down, causing neighboring columns to become unsupported, then buckle. If falling floors are capable of propagating damage west, they would also take out bits and pieces of the external frame to the north, east and south. Even the broken windows that we can see do not have falling concrete, beams, furniture or the like flying out of them. That shows that buckling of the exterior moment frame only is not what we saw in that 2 seconds of free fall.