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Re: ASCE 7-05 Wind (again)

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        Actually, the pressure is a function of the SQUARE of the velocity.  (98/85)^2=1.26.  26% is significant, I think.
H. Daryl Richardson
----- Original Message -----
Sent: Wednesday, April 30, 2008 7:27 PM
Subject: RE: ASCE 7-05 Wind (again)

I?m not overly familiar with ASCE7-05. But the reference pressure  (qz) calculated for 85 mph wouldn?t be that much different than for 90 mph, and the net pressure coefficients for an over hang are fairly high. So suggest either use the values for 90mph, or work through the detailed section of the code. The figure you refer to is for simplified method, and limited to exposure B. Some where in the code should be the pressure coefficients for the over hang, if not explicitly given then the extreme value is the combination of the windward wall pressure coefficient and the roof external coefficient.



Conrad Harrison

B.Tech (mfg & mech), MIIE, gradTIEAust



South Australia

From: Doug Mayer [mailto:doug.mayer(--nospam--at)]
Sent: Thursday, 1 May 2008 09:47
To: seaint(--nospam--at)
Subject: ASCE 7-05 Wind (again)


There is something odd about Figure 6-3 (pg 44) for determining pressures on roof overhangs ? there are no values for V=85 mph.  I have looked through the code and I can?t find any reference as to why this omitted and what I should do for values in this case.  Can I neglect it, or do I use a minimum of 10psf, or do I just use the values for V=90 mph?  Any help/guidance on this would be appreciated.




Doug Mayer, SE

Structural Engineer


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