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RE: ASCE 7-95 question...

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Title: RE: ASCE 7-95 question...
John:
 
You wrote:
"I have never sat down and compared the results of fig 6-3 to 6-4.  Does anyone know if the results vary significantly between methods?"
 
Back in 1995, I made such a comparison (for a 60 ft tall building, 90 mph wind, I = 1).  Here is what I found with respect to wind base shear.
 
If you normalize the results of the comparison by the low-rise value (which is not affected by the "actual" exposure, instead being based on exposure C), the base shears are as follows:
 
Low-rise: V=1
 
Exposure A: V=0.70
Exposure B: V=1.13
Exposure C: V=1.63
Exposure D: V=1.91
 
The implication is that low-rise buildings get a significant break.  Therefore, it is not surprising that (as I've been told by ASCE 7 committee members) the metal building folks lobbied strongly for the low-rise procedure.
 
Regards,
Mike
 
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Michael Valley, P.E., S.E.                       E-mail: mtv(--nospam--at)skilling.com
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