R H Nigl reports:
The typical floor structural configuration for the World Trade Center Towers spanned from the exterior wall columns to where the inner 49 columns formed support for the elevator shafts, stair towers, air shafts and mechanical systems… Thus, each floor was NOT a monolithic slab and structural system spanning across each tower from one exterior wall to the other three, as we are led to believe.
Each floor, in fact, terminating at the contiguous inner structural service core, resembled a square ‘donut’, with the core area being the ‘donut hole’, so to speak. Failure of floor structural support in any quadrant of the building plan, or even in any half, thus, would have failed asymmetrically.
And then there is WTC 7, which wasn’t even hit by a plane.