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RE: Texas Twisters

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Title: RE: Texas Twisters

Mark:

You are correct.  With very few exceptions (such as nuclear power plants), tornadoes are not part of the design criteria for building and bridge projects.  As you surmise, it is a matter of economics, and also a matter of acceptable risk.  Risk is an inherent and accepted part of life.  During the recent storm in Fort Worth, one unfortunate 19 year old man briefly stepped out of the pizza parlor where he worked in order to move his truck during a hail storm.  He was struck in the head by a softball-sized hail stone estimated to be traveling at a speed of 100 mph, and died instantly.

Although tornadoes are intense, they are both infrequent and very localized.  If we had to design for tornadoes, and their airborne debris (a.k.a. missiles), buildings wouldn't have any windows and very few doors.  This just isn't practical.  Instead, the emphasis in "Tornado Alley" is on early warning systems with sirens, as well as on known safe refuge areas, such as storm cellars, FEMA safe rooms, basements, stairwells, interior bathrooms, etc.

Regards,

Stan R. Caldwell, P.E.
Proud Badger in Dallas

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-----Original Message-----
From: Mark E. Deardorff [mailto:MarkD(--nospam--at)DandDEng.com]
Sent: Friday, March 31, 2000 10:22 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: Texas Twisters


Being from California I have never had to design for a tornado. In fact, I was under the impression that the most design anyone ever actually does is to pray that the tornado misses the building.

If required to endure the extreme loads a tornado can produce, how could a light-weight flat roof ever be economically designed?

Mark