Author Topic: Remembering 9/11  (Read 911 times)

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Offline Spotted Horses

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Re: Remembering 9/11
« Reply #20 on: September 12, 2021, 04:19:11 AM »
Something about the initial fireballs and shock being channeled down the elevator shafts and into the basements as well, I believe.

That happened, but the precipitating event for the collapse was that the structure at the impact point gave way.  The portion of the building above the impact point started to fall onto the lower portion like a giant hammer, pulverizing it. Later NIST did a detailed analysis, reproducing the sequence in which various structural elements failed (verified by video taken of the building). But the basic mechanism was that the impact took out part of the support structure and the remaining structure failed after being weakened by fire. Basically one beam breaks, the puts more stress on the next beam, which beaks, which puts more stress on the next beam, etc The increase in stress on the remaining structure keeps increasing, creating an avalanche of failure and a sudden collapse.

Offline BasilValentine

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Re: Remembering 9/11
« Reply #21 on: September 12, 2021, 06:11:11 AM »
I was in bed in a less than fully conscious state on 204th Street in Manhattan, a half kilometer from the Hudson River, when I was roused by the uncharacteristically loud sound of a plane flying nearby. That location isn't on any standard flight path for large planes, so the event was notable. When my mother called from Pittsburgh a short while later to ask if I was safe, I said "Why do you ask?" She answered: "Turn on your TV." I later learned that one of the hijacked planes had used the left (east) bank of the Hudson as its guide to a target eleven or so miles south of my apartment. I'm not sure that was what I had heard, but since a hijacked plane passed at low elevation less than a half kilometer away, I think it likely.
« Last Edit: September 12, 2021, 06:18:04 AM by BasilValentine »

Offline BasilValentine

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Re: Remembering 9/11
« Reply #22 on: September 12, 2021, 06:33:16 AM »
Something about the initial fireballs and shock being channeled down the elevator shafts and into the basements as well, I believe.

The context in which I've heard that discussed is in the refutation of conspiracy theories suggesting that demolition charges intentionally set near the base of the buildings were responsible for the collapses. It seems the conspiracy theorists had mistaken the effects of fire channeled down the elevator shafts for explosions near street level. I haven't heard that anyone thinks shock waves channeled down the shafts had anything to do with the collapse. I believe it's accepted that the loss of structural integrity in horizontal steel girders due to the heat led to the collapse of the immediately affected stories followed by pancaking downward.