Nathan corrected: boeings, buildings, bureaucracy

Marco Anglesio mpa at the-wire.com
Fri Sep 14 10:58:42 PDT 2001


On Thu, 13 Sep 2001, M.Blackmore wrote:
> fail. Heating for a time (dunno what time but not as long as one would
> think) will lead to a loss of strength and increased elasticity. Once
> structural members in one place have distorted sufficiently for, say, a

I wouldn't think that it would be mechanical distortion but rather a buckling (Euler buckling, IIRC - it was so long ago) of the structural members at the one floor, resulting in fifteen or twenty floors of floors, beams, and contents dropping onto the next.

Floor sections falling aren't uncommon occurrences on construction sites, especially given modern construction techniques. They can, but don't always, cause the next one below to collapse in turn.


> I suspect there will be a lot of work done to assess the structural
> capabilities of large buildings to sustained heating. And also impacts of

IIRC, a structural engineer on tv (I admit to being riveted to tv and internet feeds, all day) said that the steel could withstand direct flame for about two hours before failing under load; that's why they're insulated and a fire control system protects them directly. That's about what it took on the WTC.


> large aircraft. It seems people thought about the impact of a large
> aircraft - the building withstood this - but perhaps didn't think enough
> about the impact of very large quantities of fuel burning (and potentially

Well, in their defense, when aircraft crash on take-off, it's usually fairly close to the airfield. Their most likely scenario would probably be an aircraft trying to navigate to a NY-area airport in poor weather. That's what happened to the Empire State building.

Marco

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