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Re: Wind Exposure

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Yep.  I had such experience with some jurisdictions, like the City of Yorba Linda, where they told me that I should feel lucky with the Exposure C only, as they just dropped a mandatory 80 MPH wind requirement. 
 
However, for light structures even in the proximity of the fault, Exposure C wind may govern big time, and necessitate much heavier diaphragms, hardware, and footings.  In the residential construction/remodel business, an "automatic" Exposure C may spell big bucks for the client on a budget. 
 
Steve Gordin SE
Irvine CA
 
 
----- Original Message -----
Sent: Monday, January 09, 2006 2:28 PM
Subject: Re: Wind Exposure

I would agree with Exposure D for Ed.
 
Steve, you are correct that exposure B is permitted in CA, but you need to be careful.  I have had local jurisdictions interpret the CBC to require exposure C unless aerial studies are performed to justify a lower exposure; and these were just simple buildings, not OSHPD or DSA.  We have run into this enough times we typically just assume exposure C regardless.
 
----- Original Message -----
From: S. Gordin
Sent: Monday, January 09, 2006 1:48 PM
Subject: Re: Wind Exposure

Mark,
 
Check CBC 1619 and 1619A, Exposure B is definitely allowed, even for OSHPD projects.  I used it many time. 
 
Ed,
 
The subject case could have been Exposure B, except for the fact that Exposure B (and C) definition clearly refers to "terrain" as opposed to "terrain facing large bodies of water" of Exposure D definition.  Therefore, in the subject case, Exposure D is more in line with the apparent intent of the code.
 
Steve Gordin SE
Irvine CA
 
----- Original Message -----
Sent: Monday, January 09, 2006 1:25 PM
Subject: RE: Wind Exposure

The State of California B/C does not allow the use of Exposure B under any conditions. You can use C or D however. If you?re not in CA check with your B/D.

 


From: Ed Tornberg [mailto:ed(--nospam--at)tornbergconsulting.com]
Sent: Monday, January 09, 2006 12:33 PM
To: seaint(--nospam--at)seaint.org
Subject: Wind Exposure

 

Let?s say I have a house that?s 600 feet or so from the ocean, West coast.  ASCE 7-02 governs.

 

Between the waterline and the house is a hill, evergreen trees, and other houses.  It?s clearly surface roughness B all around.

 

Question1 :  What is the design wind exposure?

 

Question 2:  would it make any difference if using the 1997 UBC?

 

Thanks,

 

Ed Tornberg

Tornberg Consulting, LLC

503-551-4165