Improbable Collapse - new 9/11 video

Well I watched that video which doesn't really tell me anything. But if the core was still standing, after the outer walls fell, what caused the core to collapse?

The core was the strongest part of the building, right?

Originally posted by ANOK
Well I watched that video which doesn't really tell me anything. But if the core was still standing, after the outer walls fell, what caused the core to collapse?

Something once again symmetrical, at the base, because the "global" collapse of the spire was a straight drop, without any leaning. The partial collapse from lateral bracing failing before that was what one would expect, imo, and it fell on its own accord. It seems like something was initiated at the base of the core after that, though.

The core was the strongest part of the building, right?

Yep. The core could've stood by itself easily as long as wind loads weren't too heavy. The perimeter columns/trusses buffered against major wind loads, but the core was actually what was bearing the majority of the gravity loads of the whole building. Without it, the floors would have just fallen inwards, and the building would have imploded inside of the mesh of perimeter columns.


More...

Contrary to this is the behavior of the actual collapse, which suggests to me that the trusses were destroyed floor-by-floor, and the cores either blasted slightly ahead of this wave, or slightly behind it. A lot of the perimeter columns fell away still-attached, which suggests explosives generally weren't planted on the perimeter columns:



On the other hand, I've never seen a truss even remotely intact, in ALL of the Ground Zero photos I've ever seen, and very little of the core structure.

[edit on 11-12-2006 by bsbray11]

Well all the fire chiefs there were certain the building would not collapse, they were only worried that the upped floors above the fires might collapse in time.

Quote from the 911 commision report:

None of the chiefs present believed a total collapse of either tower was possible. Later, after the Mayor had left, one senior chief present did articulate his concern that upper floors could begin to collapse in a few
hours, and so he said that firefighters thus should not ascend above floors in the sixties.

Thanx bsbray I totally agree with your answers...

It seems to me, without seeing the whole vid, that they are ignoring the tilt of the building initiating at the impact point. It should have continued in it's path and fell off to one side. Once the top starting tilting it took all the energy to create a vertical symmetrical collapse away, and was only putting it's weight on one side the of the building, the pivot side. There must have been something to cause the lower undamaged floors to fail.

This to me proves, for one, that a pancake collapse was not possible, and two, there must have been some type of energy acting on the lower floors, in a controlled way, to cause the floors to turn into dust, the core to fail completely, and to cause the outer columns, weighing in the tons, to be ejected up to 600 ft away.

They do not address this in that video...