Tilt,
Given the idea that intial failure was due to 'torque' or twisting of structure beyond it's limits, this twisting certainly did not continue the entire distance to the ground. At some point the cascadeing floor into floor theory is energy transmitted directly towards the ground. And what of there being no stacks of floors?
Again, the entire length of the massive center colums must be called to question. All metal tends to dissipate heat. A good analogy given in my first link was like pouring syrup on a plate. It will spread to all directions possible. In order to make the syrup stack the least bit you must poor it faster and faster but still with little stacking effect. No matter how the columns were attached together (i did not mean to make them out as a single piece of steel) they were together. If the twisting motion could not carry to the ground, the center columns could not have been comprimised to the ground? Does this make sense?
Also, did the towers not have inter and outter support columns? From the pictures I have seen I believe they did.
Furthermore, what are your theories on the fall speed of both the twin towers? With the cascading theory one floor fell into the next building momentum on the way down. Even with this idea, does it seem right to consider since the towers fell at very near freefall speed that each consecutive floor presented no affect in slowing the fall? Does it also go to reason that near the top, before the fall built momentum, that each floor would have presented some sort of force to slow the fall? If this were true, and the buildings fell at freefall speeds, doesnt that mean the lower floors must break the laws of physics and fall faster than gravity accelerated them??