Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

RE: Tornadoes

[Subject Prev][Subject Next][Thread Prev][Thread Next]
John,

Please do post the results of your survey.  

Also bear in mind that the wind speeds equated with tornadoes ranked according to the Fujita scale are 1/4 mile winds.  It makes conversion to a fastest mile or 3 second gust an interesting exercise.  I doubt that you will find this information in any text.  I got the relationship to wind velocity from Dr. Fujita.

It is telling that there are so many deaths from wind, but there is very little research when compared to seismic.

Regards,
Harold Sprague, PE, Office Manager
Krawinkler, Luth & Assoc.
4412 W. Eisenhower Blvd.
Loveland, CO 80537
Voice: 970 667-2426
Fax: 970 667-2493
Email: hsprague(--nospam--at)klaalov.com



-----Original Message-----
From:	John Cannon Jones 
Sent:	Friday, April 17, 1998 10:35 AM
To:	'seaoc(--nospam--at)seaoc.org'
Subject:	Tornadoes

{F. LEW} It's great that this reality-check question has registered with some members
of this listserv, even if it is incorrectly attributed.  The tornadoes last
week in Arkansas killed about as many people as Northridge or Loma Prieta, yet
likely will be forgotten a year from now, whereas Northridge and Loma Prieta
have influenced, and will continue to influence, codes for years to come, and
jack up construction and design costs in the process.   
      
      In this century, at least several times more deaths have been caused by tornadoes and hurricanes
      than by earthquakes, yet the bulk of the research on natural hazards
      mitigation in recent years have been on earthquakes.  And, of course, lets not
      forget the increased costs for seismic-related design time, structural
      observations, etc., by design professionals.  On a where-are-the-bodies test
      with respect to public safety, seismic design should command much less
      construction and design resources than it now gets.

[john]  I completely agree with the statements made about seismic design.  I think most everyone in the East is hoping/praying that BOCA and SBCCI can beat some sense into ICBO.

[john]  The tornadoes from last Wednesday were primarily in Alabama.  Though there may have been some in Arkansas we had around 31 killed in Birmingham (about a 30 min drive from me) and two killed in the town where I live.  Better construction could have helped some of the buildings but not all of them.  The main tornado was classified as F5 which means that the wind velocities were estimated at greater than 260 mph.

On a side note:

A few weeks ago there was a discussion about wind and pre-engineered (PEMB) buildings.   A large church about 15 minutes away had some interesting results from the storm.  A PEMB section was being added (currently under construction) to an existing sanctuary made with brick and glulam arches.  The PEMB part now looks like a pile of matchsticks while the glulam and brick looks pretty good.  
Another building under construction that is part of the same facility was scheduled to be turned over to the owner the very next day after the tornado hit.  This building was pre-engineered but it had a walking track around the perimeter.  The track was made of block bearing walls with bar joist framing and concrete slab.  This part did quite well while the PEMB around it is pretty much gone.  A section of about 25' of CMU did blow out.  One odd thing though is that the bond beam is still there with joist and slab intact.  This 8" deep bond beam is spanning 25' with about 40 psf on it and is only sagging about 2"

The signage for this church was found in Gadsden, AL which is about 50 miles from the church.

This is taken from a quick observation from my boss.  Early next week both of us are going out for an in depth look.  Also, this is NOT a project that we designed.  We are only looking at the damage and advising the contractor what to do.

If anything interesting pops up from the in depth site visit I'll post it.

John Jones
Pell City, AL





<<application/ms-tnef>>