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Originally Posted by duckznutz
I think everyone is getting tied in knots a little here.
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God knows I've been tied in knots about this topic before, so I wouldn't be surprised.
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Originally Posted by duckznutz
I am an Architect . . here are the facts : -
1 - Think of the towers as tall square 'tubes'. The external skin IS structural and acts with a very lightweight lattice floor plate structure spanning to the central core (to acheive collumn free commercial spaces).
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Yes, this is 100% true, and is supported by both the conspiracy and the non conspiracy side of the discussion.
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Originally Posted by duckznutz
2 - It was not 'big steel girders' which 'melted'. The towers were the worlds first masonry-free high rise towers and the steel was protected with lightweight fire-board (drywall as I think you guys call it over there).
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Also completly true. Right there with you so far.
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Originally Posted by duckznutz
3 The aircraft hit the buildings at slightly different angles. One had more damage to the central core than the other and in both cases the impact and explosion 'blasted off' varying amounts of fire protective boards in each case.
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Yep. I'm with you there. An explosion from 3,500 gallons of exploding jet fuel is more than enough to strip a lot of drywall.
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Originally Posted by duckznutz
4 It is widely accepted that it was failure of the connection of the lattice floors to the central core which precipitated the collapse. It doesnt take much heat to warp lightweight lattice steel, especially when its fire protection is gone, plus the fact that the external stressed skin facade was seriously weakened in the initial impact.
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I've never heard that. Actually, I've never heard of "lattice steel". "Steel lattice" is the way people describe the hollow steel tubes surrounding a strong central core (as opposed to bracing the buildings corner-to-corner or using internal walls). A steel lattice was put in place to try and fix the problem with space versus the problem of wind sway. The steel used in the outter supports, the steel lattice, was still primarily iron and carbon. The melting point of iron is 1538 °C (2800 °F). Carbon belts at 3527 °C (6381 °F). The exterior walls were the light steel you speak of and concrete. Those did not bear any weight. The central core of both WTC buildings takes all the gravity loads of the building. Those are not made of a light steel. Those are the reason the building would have collapsed. Those are made of the metal that cannot melt because of a kerosene fire. The imagery of the WTC doesn't even reveal the aluminum siding of the WTC towers deforming. Let's also not forget about the time frame. Even the lightest steel takes a while to begin to lose it's strength.
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Originally Posted by duckznutz
5 When the critical number of lattice connections had failed in fires which were burning entirely uncontrolled (fueled not only by aviation fuel but by offices full of carpet furniture and paper) then the floor plate would collapse. When that happened, the weight of the concrete slab on top of the lattice structure would fall 12' and slam into the floor below and so on and so on.
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I'll work on this one when I have more time.
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Originally Posted by duckznutz
If you are a construction professional its not so hard to understand. Remember, these were the days before progressive collapse building codes were introduced.
http://www.civil.usyd.edu.au/wtc.shtml |
Well, as I said I'm ony a layman.
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Originally Posted by duckznutz
The aircraft with no windows? . . .well thats maybe another story.
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I've seen no evidence of this beyond eyewhitness reports (which are unreliable). Thanks very much for the post! I hope I have given you as much to think about as you have me.