From: "Mark D. Anderson PE" <mark(--nospam--at)alaskaengineer.com>
Date: Tue, 12 Jun 2001 14:17:13 -0800
Dennis, the only exposure more severe than exposure "C" is "D", and by
definition its applicability is limited to coastal locations with at least
one mile of fetch. This has been true since the various exposures were
conceived, which I think was A58.1-1982.
So from a code compliance point of view, you are on thick ice using exposure
"C" if you are away from a shoreline of open water with a mile of fetch.
Mark D. Anderson PE
----- Original Message -----
From: "Structuralist" <dennis.wish(--nospam--at)gte.net>
To: "SEAINT Listservice" <seaint(--nospam--at)seaint.org>
Sent: Tuesday, June 12, 2001 1:54 PM
Subject: What Exposure to use?
> This is the first time that I have had this one happen. I called the city
> Indio California to obtain the local wind load design criteria. I was told
> that to use an 80-mph wind, but when I asked what exposure to use, the
> Building Official responded with - "Your the engineer, you determine that!
> Use a minimum of at least Exposure C."
> There is quite a difference between Exposure C and D which has me worried.
> The sign is a 25'-0" tall pole with a 60-s.f. (6'-0" high x 10'-0" wide)
> sign. The sign occurs in a windy off the freeway, however, the freeway is
> lined with trees intending to create a wind break. This prevents sand from
> blowing over and building up on the freeway.
> How can an engineer determine the specific wind load conditions for a very
> specific site if the building official will not provide the information?
> Any suggestions? The sign is for an Auto Body Repair store located on the
> road running parallel to the freeway. The area is open with industrial
> buildings close by, but the area is open for miles.
> Dennis S. Wish, PE
> Structural Engineering Consultant
> (208) 361-5447 E-Fax
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