New WTC report (bolsters the case more for LIHOPers than MIHOPers)

[cynatnite]

I snipped a few parts from one of the summaries concerning what caused the fall of the towers. At the web site there is a lot of infomation. The reports which are .pdf files also include pictures and diagrams.

Before anyone just shoves it aside because of the '.gov' in the URL address it would be nice if those who seek facts take the time to go through the abundance of information.

I have been reading it off and on. I'm about halfway through and I've got to say it is thorough and explains a great deal. It answers many questions for me.

http://www.nist.gov/public_affairs/releases/wtc_briefin...

The two aircraft hit the towers at high speed and did considerable damage to principal structural components: core columns, floors, and perimeter columns. However, the towers withstood the impacts and would have remained standing were it not for the dislodged
insulation (fireproofing) and the subsequent multifloor fires. The robustness of the perimeter frame-tube system and the large size of the buildings helped the towers withstand the impact. The structural system redistributed loads without collapsing in places of aircraft impact, avoiding larger scale damage upon impact. The hat truss, a feature atop each tower which was intended to support a television antenna, prevented earlier collapse of the building core. In each tower, a different combination of impact damage and heat-weakened structural components contributed to the abrupt structural collapse.

In WTC 1, the fires weakened the core columns and caused the floors on the south side of the building to sag. The floors pulled the heated south perimeter columns inward, reducing their capacity to support the building above. Their neighboring columns quickly became
overloaded as columns on the south wall buckled. The top section of the building tilted to the south and began its descent. The time from aircraft impact to collapse initiation was largelydetermined by how long it took for the fires to weaken the building core and to reach the south side of the building and weaken the perimeter columns and floors.

In WTC 2, the core was damaged severely at the southeast corner and was restrained by the east and south walls via the hat truss and the floors. The steady burning fires on the east side of the building caused the floors there to sag. The floors pulled the heated east perimeter columns inward, reducing their capacity to support the building above. Their neighboring columns quickly became overloaded as columns on the east wall buckled. The top section of the building tilted to the east and to the south and began its descent. The time from aircraft impact to collapse initiation was largely determined by the time for the fires to weaken the perimeter columns and floor assemblies on the east and the south sides of the building. WTC 2 collapsed more quickly than WTC 1 because there was more aircraft damage to the building core and there were early and persistent fires on the east side of the building, where the aircraft had extensively dislodged insulation from the structural steel.

The WTC towers likely would not have collapsed under the combined effects of aircraft impact damage and the extensive, multifloor fires if the thermal insulation had not been widely dislodged or had been only minimally dislodged by aircraft impact.