Wind Pressure Minimum requirements
Wind Pressure Minimum requirements
(OP)
Hello,
Both ASCE 7-10 (28.4.4) and IBC 2012 (1609.6.3) list minimum wind pressures at 16 psf for walls. ASCE 7-10 also lists 8 psf minimum for vertical projections of roofs.
The minimum wind load comes into play on single story structures particularly in exposure B. There has been much written about LFRD vs ASD wind design. IBC has a conversion factor (1609.3.1). It seems obvious to me that 16 psf is an LFRD minimum wind pressure. 16/1.6 = 10 psf should be the minimum ASD wind pressure similar to ASCE 7-05.
The issue I am having is that neither code specifically lists this minimum value as an LFRD value and many Governing Agency building officials are now requiring the use 16 psf minimum for ASD lateral design of one story wood buildings. What literature is available that addresses this item - particularly ASCE or IBC sourced?
Thanks,
Rich Warren
S3 Engineers
Both ASCE 7-10 (28.4.4) and IBC 2012 (1609.6.3) list minimum wind pressures at 16 psf for walls. ASCE 7-10 also lists 8 psf minimum for vertical projections of roofs.
The minimum wind load comes into play on single story structures particularly in exposure B. There has been much written about LFRD vs ASD wind design. IBC has a conversion factor (1609.3.1). It seems obvious to me that 16 psf is an LFRD minimum wind pressure. 16/1.6 = 10 psf should be the minimum ASD wind pressure similar to ASCE 7-05.
The issue I am having is that neither code specifically lists this minimum value as an LFRD value and many Governing Agency building officials are now requiring the use 16 psf minimum for ASD lateral design of one story wood buildings. What literature is available that addresses this item - particularly ASCE or IBC sourced?
Thanks,
Rich Warren
S3 Engineers






RE: Wind Pressure Minimum requirements
If the building department is requiring a minimum 16 psf ASD pressure, it could be that they do not understand how the code was revised. You could argue that the ASD load combinations include a 0.6 factor for wind forces.
RE: Wind Pressure Minimum requirements
RE: Wind Pressure Minimum requirements
RE: Wind Pressure Minimum requirements
RE: Wind Pressure Minimum requirements
RE: Wind Pressure Minimum requirements
DaveAtkins
RE: Wind Pressure Minimum requirements
When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.
-R. Buckminster Fuller
RE: Wind Pressure Minimum requirements
I have met the the plans examiner on this item. I have attempted to explain the use of load factors. He understands them very well. He is just saying that the code specifies a minimum value of 16 psf and that he needs something in writing from IBC or ACSE... I have had this issue with more than one plans examiner and they usually get it after a brief discussion. However, I have one examiner that refuses to budge...
Guess my next step is to request a code interpretation from IBC. However, I am not a member. I will call them to ask if it is possible to get one as a non-member.
RE: Wind Pressure Minimum requirements
Maybe I don't understand the argument.
EIT
www.HowToEngineer.com
RE: Wind Pressure Minimum requirements
Thanks,
Rich
RE: Wind Pressure Minimum requirements
EIT
www.HowToEngineer.com
RE: Wind Pressure Minimum requirements
Maine Professional and Structural Engineer. www.fepc.us
RE: Wind Pressure Minimum requirements
As suggested above, it seems like the best thing to do is change your calc spreadsheet to deal with the conversion from LRFD to ASD inside the black box so that the plans examiner can only see what he is able to understand and is none the wiser to the things he doesn't understand.
RE: Wind Pressure Minimum requirements
RE: Wind Pressure Minimum requirements