[CEUS-earthquake-hazards] no "right" answer

[Wang, Zhenming]

Joe,

I have been told by some structural engineers that it is wind load, not seismic load that governs the structural design in most parts of Kentucky (central and eastern). Have you done any design analysis on these? It would be interesting to see the load comparisons.

Thanks.

Zhenming

________________________________
From: Joe Tomasello [mailto:JT at ReavesFirm.com]
Sent: Thursday, February 14, 2008 12:39 PM
To: 'Seth Stein'; WrightLa at usa.redcross.org
Cc: Wang, Zhenming; ceus-earthquake-hazards at geohazards.usgs.gov; cfostel at conwal.com
Subject: RE: [CEUS-earthquake-hazards] no "right" answer

Seth, et al:
This firm has been involved with recovery efforts of the tornado strikes of February 5, 2006.  The tornado damage shown in the attached is perceived by the locals to be the primary day to day threat from natural hazards.

The failure mode is rather simple; the wind lifts the roof deck and buckles the joists, which in turn pulls inwardly on the top of the precast panels causing them to fall (see Image 647 and 307).  Evidence indicates that the lateral force resistant system remained standing (see Image 313), however a majority of the building collapsed. This design is pre-1997 NERHP, but included seismic considerations. It's unlikely that additional seismic resistance required by 1997 NERHP would affect the outcome.

What I'm suggesting is that contrary to the accepted convention (more seismic is better), we think there can be a case made that seismic design does not cure all the ills created by the various different natural disasters as advertised by FEMA.

Image 647 - shows failure mode

Image 313 - Shows seismic bracing

Image 307 - Shows failed panels large warehouse






-----Original Message-----
From: ceus-earthquake-hazards-bounces at geohazards.usgs.gov [mailto:ceus-earthquake-hazards-bounces at geohazards.usgs.gov] On Behalf Of Seth Stein
Sent: Wednesday, February 13, 2008 7:58 PM
To: WrightLa at usa.redcross.org
Cc: zmwang at email.uky.edu; ceus-earthquake-hazards at geohazards.usgs.gov; cfostel at conwal.com
Subject: Re: [CEUS-earthquake-hazards] no "right" answer



Both are problems, but in the US severe weather kills about 500 people per year and earthquakes kill about 10. Another way to look at this is that every 6 years severe weather has the same net effect as the 1906 San Francisco earthquake.



Seth Stein

William Deering Professor

Department of Earth and Planetary Sciences 1850 Campus Drive Northwestern University, Evanston, IL 60208

(847) 491-5265 FAX: (847) 491-8060 E-MAIL: seth at earth.northwestern.edu<mailto:seth at earth.northwestern.edu> http://www.earth.northwestern.edu/people/seth



On Wed, 13 Feb 2008 WrightLa at usa.redcross.org<mailto:WrightLa at usa.redcross.org> wrote:



> When earthquakes don't happen, tornadoes are a bigger problem.

>

>

>

> The recent loss of life due to tornadoes is horribly tragic, and not

> to be belittled by any means, but the loss of life that could be

> caused by an 1811 quake in the NMSZ beggars the imagination.

Joseph Tomasello, PE
5880 Ridge Bend Rd.
Memphis, TN 38120

Phone:
(901) 761-2016 office
(901) 821-4968 direct
(901) 412-8217 mobile
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