Randall wrote:
>
> david rann wrote:
> > The engineers could play with numbers
> > for months or longer to come up with no economical alternative. I doubt that
> > a riveted structure could have withstood such an assault. Surely in the
> > future these considerations will be considered in building design, but the
> > "Capitalists" will be hard pressed to pay extra for public safety.
>
> One of the news bites I heard during the disaster was that the original
> architect had commented that the structure was designed to withstand a
> direct hit from a commercial aircraft. I wonder what happened ? Did he
> not account for the burning fuel, or is it just that jets have gotten
> bigger ?
I read a post-mortem of the structure failures a couple of days ago, and
the general consensus of the architects and the engineers is that the
original design planned for the impact of a 707. A 757 or 767 would be
somewhat larger, thus the kinetic energy would be larger. But, the
overall impression, without samples from the failed buildings, was that
fire was the reason for collapse. Their belief is that the heat from the
fire was sufficient to melt the moorings and attachments for the floors
in the area of the impact, which caused the upper floors to dislodge,
one on top of the other, until there was sufficient mass to mechanically
break the moorings of the lower floors. Then everything came down like
dominos.
Since portions of the foundation and the wall structure around the first
few floors were partially intact, there's little suggestion of a
foundation failure resulting from impact.
And, there's one report, possibly unsubstantiated, of one man trapped on
one of the upper floors who survived by literally riding the pieces of
the floor down to the ground. And, floors collapsing one onto the other
is reasonably consistent with the film of the buildings failing. Even
the best-designed building is still subject to "the best-laid plans of
mice and men...." <sigh>
--
Michael D. Porter
Roswell, NM (yes, _that_ Roswell)
[mailto:mporter@zianet.com]
The gulf between content and substance continues to widen....
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