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> You act as though the curtain walls: > 1) were not attached to the inner structure (beams and columns)
They weren't. The curtain walls were attached to the exterior columns and spandrel beams. If you're referring to how those columns and beams were connected to interior columns and beams, here's a clue for you: If you don't know anything about the connections used in WTC7, and you don't understand why it matters, then you have no business wasting people's time with ignorant speculation about what caused the collapse or imaginary flaws in the NIST analysis.
> 2) didn't fall at free-fall speed
Eh? What the hell does that have to do with what we're talking about? Everything falls at free-fall acceleration when there's nothing preventing it. If you are under the delusion that I buy the idiotic notion that free-fall acceleration = demolition, you are sadly mistaken. The NIST simulation shows why WTC7 experienced a brief period of free-fall acceleration, and you can see it in the video you posted: The progressive collapse spread vertically across about 8 lower floors before the top began to fall. After allowing the top to fall only a few feet, those columns were buckled to the point that they presented virtually no resistance to the top falling at near free-fall acceleration until it collided with the intact structure below.
> 3) provided stability and rigidity but had no effect on the collapse of the inner structure.
The curtain walls apparently had enough rigidity to hold the basic box shape of the top part of the building as it fell, but none of the videos show what was happening lower down or inside the building. But yes, I'm saying that this rigidity had no significant effect on the load-bearing structure's ability to resist the progressive collapse.
You completely dodged my point, so I'll say it again: There is no logical reason to expect the exterior columns in the simulation to look like the real building as it fell, because the simulation did not include those rigid curtain walls. But the simulation was concerned with studying the behavior of the floors and load-bearing structure during collapse initiation, not the appearance of the building's facade after the collapse was already under way.
If you think that's "complete nonsense," then I have to (again) question your understanding of simple structural mechanics, or your understanding of the purpose of the model, or both. And I have to (again) question why you persist in offering your own lack of understanding as evidence of anything other than itself.
> But, please, tell me about how ALL the facts that support collapse.
When Richard Gage wants to "explain" why the collapse didn't sound anything like a controlled demolition, he claims that thermite was used. But when he wants to explain the suddenness of the collapse and the stuff being ejected, he switches to claiming explosives used used. Gullible fools may not notice that Gage is contradicting himself and that neither hypothesis explains the facts -- i.e. what we see and don't hear in the actual collapse -- but those facts won't disappear in Gage's cloud of smoke. Another fact: Gage and David Chandler love to claim that the brief period of free-fall acceleration can only be explained by a controlled demolition -- an absurd assertion (see above) -- but both studiously ignore the 1.5 seconds or so when the top fell several feet at much less acceleration. It's convenient for them to ignore it because then they don't need to explain how a controlled demolition could have that effect.
The NIST model explains all the known facts about the collapse, whereas the "truth movement" has yet to come up with a controlled demolition hypothesis that does. Instead of any rational, consistent hypothesis of their own or any valid technical criticism of the NIST hypothesis, all we get from the "truth movement" is incredulity, imaginary physics, and unsubstantiated speculations asserted as facts.
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