Peer-to-Peer Standards Exchange

A Plan Reviewer recently commented concerning my wind calculations using ASCE 7-10 (the adopted standard in this jurisdiction).  As is the case with many engineers designing in wood, to use ASD I apply the 0.6 load factor to qz, in lieu of applying it in the Basic Load combinations.  To me, this makes the loads much easier to track to the foundations.  The Reviewer Stated:

"The minimum design wind loading for the main wind-force-resisting system and components & cladding shall be not less than 16 lb/sq.ft. (and some allow minimum 8 lb/sq.ft. for roofs). Page 5 shows component & cladding loadings as below 16 psf for 26 of the 44 cases, which is unacceptable, revise to comply."

Another issue is the proper application of the minimum wind loads. Does every calculated pressure design pressure have to exceed the minimum, or is the minimum a separate load check like Components & Cladding.

Thanks to the forum in advance.

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Patrick McGuire P.E., M.ASCE
Engineer
Consultant
Boston KY
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Hi Patrick,

Are you asking if you can use a load less than 16 psf for any portion of your calculations for the MWFRS?  Based on ASCE 7-10 you cannot use a pressure below 16 psf for any calculation.  Typically your component and cladding load will be much higher and the connections for those items to the MWFRS need to be based on the load from the higher load to avoid failure.

The relevant minimum from ASCE 7-10:

27.4.7 Minimum Design Wind Loads
The wind load to be used in the design of the
MWFRS for an enclosed or partially enclosed
building shall not be less than 16 lb/ft2 (0.77 kN/m2)
multiplied by the wall area of the building and 8 lb/ft2
(0.38 kN/m2) multiplied by the roof area of the
building projected onto a vertical plane normal to the
assumed wind direction. Wall and roof loads shall
be applied simultaneously. The design wind force
for open buildings shall be not less than 16 lb/ft2
(0.77 kN/m2) multiplied by the area Af.

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Sarah Halsey P.E., M.ASCE
New York NY
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