Subject:
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Re: My Prayer on this National Day of Prayer
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Newsgroups:
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lugnet.off-topic.debate
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Date:
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Sat, 15 Sep 2001 00:43:40 GMT
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Viewed:
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678 times
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In lugnet.off-topic.debate, Thomas (T. J.) Avery writes:
> In lugnet.general, Larry Pieniazek writes:
> > It is a stunning testimonial to the architects and engineers of WTC... steel
> > melts, and concrete pulverises, at well below what Jet A burns at so the
> > upper floors were doomed no matter what, but even with supports unevenly cut
> > away the towers lasted a while, and when they went down, they went
> > *straight* down in a controlled collapse.
> >
> > Think of how much worse things would have been, had they toppled sideways
> > instead of collapsing in a controlled way.
That was the goal of the 1993 bombers, who hadn't thought things
through nearly so completely.
> > Small consolation to the thousands who died but I personally feel a huge
> > debt of gratitude to the (anonymous?) WTC engineering team, whoever they are.
>
> It is amazing that the towers didn't collapse right away, and things could
> have certainly been much worse. As an engineer, I'll be interested in future
> reports that will discuss modes of failure.
I can't recall if it's cnn.com or cbs.com, but they interviewed
five or six members of the design team who are still alive (the
prime architect died in Japan in the 1980s). They explained the
theory behind the construction and the suspected reasons for the
failure there.
> Typically, building design adheres strictly to code, and unusual occurances
> aren't covered. I haven't looked through the AISC-LRFD manual thoroughly,
> but I doubt loads from jet plane crashes are considered. It's up to the
> client to decide whether or not to spend the extra money and have their
> building designed for some extraordinary event. The decision is usually
> based on a risk assessment and a study of the consequences.
>
> I believe the WTC towers were designed to handle the impact of a 707. I'm
> sure this extra design criteria helped, but unfortunatly it wasn't enough.
IIRC, it was designed to take the impact from a 747 (the jumbo),
which was even larger than what hit the towers on Tuesday.
The problem was that the effects of a full load of fuel burning
just can't be countermanded--only slowed down, and hopefully
controlled. When the steel went, the upper floors pancaked down-
ward--the facade is what you see peeling outward. The concrete
floors went pretty much straight down, one on top of another
(which is another reason I'm not optimistic about survivors
from above the lower ten or so floors still being in the rubble).
> Nevertheless, I agree with Larry and I'm thankful that someone had the
> foresight and decided it was best to account for such an extraordinary
> event, even though it was for a smaller plane.
I've seen enough stories--and heard enough stories--of people,
some whom I know personally, getting out after the impacts.
That was critical time, and there is no question that it is
responsible for the death toll being 4,000-5,000 and not 30,000+.
> I'm sure engineers and architects will see changes in building codes soon.
> They'll seriously have to consider such events as car bombs, letter bombs,
> plane crashes, etc. It's sad, but we'll all see changes in life in
> everything we do.
So long as it does not impinge upon our Constitutional freedoms,
that's a small price to pay. Inconvenience does not equal a police
state, regardless of what a few alarmists would have us believe.
Fortunately, those in the world who must already deal with these
issues are at hand and willing to help us.
best
LFB
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Message is in Reply To:
 | | Re: My Prayer on this National Day of Prayer
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| (...) It is amazing that the towers didn't collapse right away, and things could have certainly been much worse. As an engineer, I'll be interested in future reports that will discuss modes of failure. Typically, building design adheres strictly to (...) (23 years ago, 14-Sep-01, to lugnet.off-topic.debate)
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