I didn't see anything in your last post that addressed the group that we have been discussing - AE911.
Snook left out an important part - steel-framed. Big deal. Most people who look into 911 know what he meant.
These aren't my theories. This is an interpretation of data by plenty of engineers and architects who see it differently
than the mainstream guys. Doesn't make them right or wrong. How many times must I say that to you?
I'm trying to avoid Scholars for 911 not because I feel they are wrong but because I feel it's best to stick with
engineers and architects (and explosive/thermite experts when we can find them) when discussing how the towers and WTC7 fell. As I stated before, this group didn't exist before or I wasn't aware of them. But now they are there
and growing in numbers and I will continue to see what they have to say. You can ignore it if you choose.
That's your right. There are other professionals who are relevant to this investigation (physicists, airline pilots,
etc...) but for right now, I'm concentrating on AE911.
I haven't ignored the mainstream. I know what both sides say and I lean heavily towards the ones who question
the official story. Make of that what you will. Wanna call me a CT, be my guest. I don't give a crap.
I think I will let the guys @ MIT do it for me!
How the Towers Fell
Given the lack of firm conclusions regarding how the collapses occurred, the M.I.T. panel participants asked their audience to consider various theories they put forth. In general, it was agreed that as the structure warped and weakened at the top of each tower, the frame, along with the concrete slabs, furniture, file cabinets and other materials, became an enormous consolidated weight that eventually crushed the lower portions of the structure below. The details of how the frame members failed remain under contention.
Professor Connor's theory focused on weaknesses in how the vertical and horizontal structural members were tied together. During construction, he explained, each prefabricated floor system was lifted into place by a crane and "supported at the ends like a hinge, where they were bolted and welded to the inner and outer framing tubes" so that part of the gravity load went through the core and the other part through the exterior structure. "The floor trusses sat on beams and were tied down so the core was locked to the exterior," he said. "It was an unusual system and very lightweight. If you lose the connection between them, however, you lose the ability to carry the floor loads and allow the floors to slide back and forth under stress. If a damaged floor system were to fall, it would break the end connections in the lower floors and down and down the floors would go."
"In my theory, the hot fire weakened the supporting joint connection," Connor continued. "When it broke, one end of a floor fell, damaging the floor system underneath, while simultaneously tugging (pulling) the vertical members to which it was still attached toward the center of the building and down." This phenomenon started a parasitic process that accelerated until total failure and the structure fell in on itself, he said.
Eduardo Kausel proposed an alternative failure explanation that he acknowledged was independently developed by Zdenek Bazant, a professor at Northwestern University. "I believe that the intense heat softened or melted the structural elementsâ€”floor trusses and columnsâ€”so that they became like chewing gum, and that was enough to trigger the collapse," he said. "The floor trusses are likely to have been the first to sag and fail. As soon as the upper floors became unsupported, debris from the failed floor systems rained down onto the floors below, which eventually gave way, starting an unstoppable sequence. The dynamic forces are so large that the downward motion becomes unstoppable."
Via two simple models, Kausel was able to determine that the fall of the upper building portion down onto a single floor must have caused dynamic forces exceeding the buildingsâ€™ design loads by at least an order of magnitude. He also performed some computer simulations that indicate the building material fell almost unrestricted at nearly the speed of free-falling objects. "The towers' resistive systems played no role. Otherwise the elapsed time of the fall would have been extended," he noted. As it was, the debris took about nine seconds to reach the ground from the top.
"It's difficult to judge which of these failure mechanisms occurred first; probably all occurred and interacted," said panel member Oral Buyukozturk, professor of civil and environmental engineering at M.I.T.. "The prolonged effect of high heat is likely to have led to the buckling of the columns, collapse of the floors, as well as to the shearing of the floors upon the failure the joints." He noted that videotapes of the catastrophe showed some tilting of the top portion of the south tower before it collapsed. "This indicates the buckling of one building face while the adjacent face was bending [placed into tension]." After that, the upper portions of the tower are shown disintegrating, with "a dynamic effect and amplification process" following that led to a progressive collapseâ€”"a kind of pancaking or deck of cards effect"â€”down to ground zero, Buyukozturk stated.
Kausel addressed the oft-asked question of why the towers did not tip over like a falling tree. "A tree is solid, whereas building is mostly air or empty space; only about 10 percent is solid material. Since there is no solid stump underneath to force it to the side, the building cannot tip over. It could only collapse upon itself." Robert McNamara said his failure mechanism theory "focuses on the connections that hold the structure together," but he cautioned that "we really need to wait for a detailed investigation, before we decide if we have to up the code ratings for these connections in signature structures.
Now your not going to say the boys @ MIt are in on it are you?
I think we can all agree MIT is one of the best in the country so good luck tearing them apart Joe!