[Anthem]

Re: The building structure.

The center core was a huge load bearing stuctural component. Why wasn't it left standing as the floor slabs pancaked (breaking their moorings -- a perpendicular attachment far more vulnerable to vertical moments of inertia than a vertical column would be)?

[_Jim]

The center core was a huge load bearing stuctural component. Why wasn't it left standing as the floor slabs pancaked

110 stories worth of vertical steel column standing by iteslf?

Vertical steel columns ONCE tied together via the floor 'joists' to the external load-bearing vertical steel columns?

I'd like to see the bending 'moment' at the base of those vetical beams; they would have to be built of 100% Unobtainium, which is at LEAST 1000 times stronger than diamond.

[Alberta's Child]

The center core wasn't capable of standing on its own . . . its stability was based not only on its own strength, but on its connections to the exterior frame.

Think of it like the sides of a truck that strikes a low overpass. The walls seem solid when the trailer is intact, but when a large section of the roof is buckled they suddenly lose their ability to stand up, and they collapse outward when that lateral support is lost.