Had there been a progressive total vertical failure, the building would have tilted and fallen towards the side that initially started failing (presumably the east side).
Clearly this did not happen!
oh MM, CLEARLY it did.
The first visible result of the collapse is a failure that results in the EPH falling in. This very much suggests that column 79 failed.
What happens subsequent to that is the development of the 'kink' in the north facade and the tilting of the sections east and west of that line towards this initial line of failure.
In addition, at about the same time as the tilting towards a column 79 line of failure, the rooftop structures west of the EPH then begin falling in. This highly suggests a progression of core failure. The section of the building west of the kink then falls to the south, suggesting a tilt in that direction, ie. towards the core failure.
Well MM, I admited I was wrong about J&H being at the NW corner.
,,, so you will now be admitting that the building did in fact behave in a fashion consistent with the proposed, and visible, sequence of progressive failure?
This :
"fallen towards the side that initially started failing (presumably the east side)", is where you seem to have a problem with understanding. The building's initial failure was along the line of column 79, about 1/3 of the way accross the building, from the east. This is indicated by the location of first rooftop failure and infalling of the EPH.
This is followed by a "kink" obviously affecting the entire north side of the building in that all visible floors east and west of that "kink" tilt down at the line of the "kink".
At the same time as the "kink" forms we also see the beginning of a western progression from the EPH location, of the infalling of rooftop structures. This indicates a progressive east to west loss of core strucure beginning at about the location of column 79.
So we have a leaning in towards the "kink" and then destruction of the core, which is, obviously, south of the north face of the building. The SW corner is also destroyed, having been previously hit by WTC 1 debris, while the eastern third of the south face suffered less severe damage.
You have a situation in which the western 2/3 of the structure had both an initial bulge to the south at the SW corner, and a loss of core structure causing a tilt to the south of the western 2/3 of the north side of the building. That 2/3s of the building then fell , in large part, to the south.
The eastern 1/3 suffered no significant structural damage by the debris of WTC1. When the western portion began coming down it pulled on the eastern portion which then twisted as it fell, coming down to the NE and impacting the Fitterman building which had to be torn down later.