Comment: I appreciate your reasoned questions.

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fireant's picture

I appreciate your reasoned questions.

Regarding the Twin Towers, the floors below were initially damaged and weakened due to the impact of the planes into the cores, or the transfer of energy from the floors into the cores, or both. The shock to the cores would have weakened truss connectors several floors below. The floors below also were progressively weakened as the collapse ensued due to shock to the cores and splaying of the cores. I believe floors were collapsing well ahead of the collapse line we see from the exterior. It is important to note the cores were not completely severed when collapse began. The falling tops would also have stressed the cores below. We can see from falling perimeter walls outrunning the collapse line that there indeed was some resistance on the interior. We also have an "earwitness" with the absolute best vantage point. That would be one of the survivors in Stairwell B. Listen to his comments at the :30 mark: http://www.youtube.com/watch?v=aWiCxz5ki80&feature=related
Regarding 7, since we can clearly see the interior collapse prior to the outer shell falling, it is not a stretch to assume that once the building started down, it primarily was the perimeter walls falling. The twist in the building prior to starting down is a major clue. That move alone would have weakened the joinery of whatever structure remained on the interior.

Undo what Wilson did