In the first collapse the north tower would have jack-knifed down, the south would have probably collapsed about 5 -10 floors and stopped up there.....tower 7 should have never collapsed.
Blithering nonsense.
There's no structure in the building that could have stopped the collapse once it began. The building transfered gravity load AROUND the floors through perfectly aligned vertical columns shunting that load into bedrock.
When the floors began impacting, it was floor to floor and utterly haphazard. You had structural steel colliding with floor trusses designed to support their own weight and that of say, people and desks. Not the gravity loads of dozens of stories of falling structural steel. They would have collapsed almost instantly.
Then there's GRAVITY, accelerating the debris field of dozens of floors of structural steel before they impact with the floor below. Radically increasing the forces each floor was subject to with the debris field. An increase that would have kept on increasing as the debris field accelerated.
Worse still, there's impulse....the performance of a material under quick sudden forces rather than measured, consistent forces. Structural steel has a MUCH lower load bearing capacity when subject to sudden forces than it does consistent ones. About a third less. And dozens of stories of falling structural steel accelerated by gravity are both powerful and sudden.
Finally, each floor that collapsed ADDED mass to the debris field. So you have MORE mass, MORE acceleration under gravity....while each floor truss had a static amount of resistence it could offer, which was utterly insuffecient for even ONE floor collapsing on top of it, let alone dozens, let alone dozens accelerated by gravity.
Once the first floor fell, there's literally nothing that could have stopped the collapse all the way to the ground. Instead, the collapse would have accelerated under gravity, adding more mass with each floor until it finally stopped when it collided with the ground.
Which is exactly what we saw.
