. "The most important thing we found was that there was, in fact, physical damage to the south face of building 7," NIST's Sunder tells PM. "On about a third of the face to the center and to the bottom — approximately 10 stories — about 25 percent of the depth of the building was scooped out." NIST also discovered previously undocumented damage to WTC 7's upper stories and its southwest corner."
Ok Im wondering how seven years later NIST discovered previously undocumented damage? It had to be from video footage cuz any physical evidence is long gone. So lets see the video or pics. And 25 percent sounds like a lot but has anyone seen the pics of the OKlahoma city bombing? That building sustained massive damage but did not fall.
NIST investigators believe a combination of intense fire and severe structural damage contributed to the collapse, though assigning the exact proportion requires more research. But NIST's analysis suggests the fall of WTC 7 was an example of "progressive collapse," a process in which the failure of parts of a structure ultimately creates strains that cause the entire building to come down. Videos of the fall of WTC 7 show cracks, or "kinks," in the building's facade just before the two penthouses disappeared into the structure, one after the other. The entire building fell in on itself, with the slumping east side of the structure pulling down the west side in a diagonal collapse.
So what this paragraph is saying is that the building was "progressively collapseing on the inside? Because you cant see anything collapseing in any of the vids until it all falls down.
According to NIST, there was one primary reason for the building's failure: In an unusual design, the columns near the visible kinks were carrying exceptionally large loads, roughly 2000 sq. ft. of floor area for each floor. "What our preliminary analysis has shown is that if you take out just one column on one of the lower floors," Sunder notes, "it could cause a vertical progression of collapse so that the entire section comes down."
I'll give em this one cuz I dont really know about the architecture of the building. But it seems logically that the chances of all these things happening and causeing a collapse are a million to one. It is a fairly plusible theory (and as stated in the PM piece that is all that it is.) more believe able than the pancaking floors theory of the towers.