The collapse was a dynamic event… and it progressed through time. Using tracking (precise movements of building parts, debris, smoke, ejecta etc.) of what we can see of the collapse are the results of what caused those “movements”. We may not (likely not) be able to know with complete certainly what caused each observation/movement. But certainly we can make well educated guesses based on physics, engineering, the design of the towers, and what we (think) know about the planes hitting the buildings (mech damage and fuel “delivery”).
When you observe an energetic burst of smoke (ejecta) you are safe in attributing this to an over pressure… of gas (air?). When you observe the top section moving down… you are safe to assume that the top no longer had adequate axial support. But was this from weakened columns? mis-aligned columns? Loss of columns? or a combination of these causes? The general statement – “failed” columns hardly explains how the tops got moving downward.
The tracking of multiple points that we can see showing different movements seems to indicate that the rigid 3D form was under stress ... Read even more
