[Alberta's Child]

Angular momentum isn't enough to make a building that size fall sideways. In order for a building to collapse any way but on itself, there must be sufficient lateral force to move the building's center of gravity far enough horizontally that it is outside the "footprint" of the building. I can't think of anything other than perhaps a 1,200-foot tidal wave that would be capable of exerting that kind of force on a structure that weighs about 500,000 tons.

[Anthem]

--Angular momentum isn't enough to make a building that size fall sideways

No, it wouldn't make the whole building fall. It would have fallen off the building, leaving the rest of the building standing.