Another Credentialed Individual Helping to Explain the Collapses
Dr. Thomas Eagar, became an early spokesperson for the truss theory. Although not a structural engineer, his credentials as a professor at MIT were sufficient for his role in "explaining the collapses". In the following post Jeff King points out some of the absurdities advanced by Eagar in his NOVA interview.
Do tall things topple over? by Jeff King Thursday December 05, 2002 at 01:16 AM
Professor Eagar's statement has been floating around for the past year, but doesn't really make sense at several levels. He implies that the laws of gravitation are somehow not linear, that if a small object of the same proportions (6.5/1 height to base ratio) tends to topple, a much bigger object of the same proportions will not be similarly unstable. A wooden box 1' square and 6 1/2' tall has the exact same geometric relations of center of gravity to base as a big steel box 1300' tall and 208' on a side. Nothing changes with a change in absolute size, this is the most basic Newtonian physics. Yet Eagar says "There's no other way for them to go but down. They're too big." This is complete and utter nonsense.
It also ignores the fact, as noted above by Pete Wagner, that the top of WTC-2 had clearly "broken off" and begun to tip. A big chunk of building had begun to topple, and now had linear momentum in the direction of the lean, as well as angular momentum as it was rotating about its own center of gravity. Momentum doesn't just go away without some kind of external force being applied.
Describing one of the the WTC towers as "a building that is mostly air" sounds profound but is no more valid than saying that atoms are mostly empty space, and so matter should collapse or implode at any provocation. It is a clever rhetorical flourish that does a great injustice to the structural integrity of these buildings, implying that they were houses of cards waiting to tumble down. In fact they were very rigid and had far more compressional strength than needed to avoid collapse. Each core had 47 steel box columns, all interconnected with steel plates at each floor, and trussed box columns at the corners that can be seen in the picture above supporting construction cranes. The outer "tube" comprised 256 14" square steel box columns tied together with 52" tall steel plates at each floor.
This "tube-in-tube" design, with 110 floors acting as braces that linked the two tubes together, created an extremely strong geometry allowing redistribution of stresses. To think that such a structure would magically disintegrate rather than allow itself to be tipped over is simply bizarre.