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RE: Wind loads: ASD or Strength?

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Jason,

 

I would be willing to bet that the confusion is coming from IBC section 2306.4.1, which allows the tabulated values for shearwall resistance from Table 2306.4.1 to be increased 40% for wind loads when using ASD.  The choice of ASD is a choice of load combos, as you said, and happens after V is calculated.  Dividing the load is bad practice, though, because this increase in resistance applies only to shearwalls and diaphragms, not to everything connected above & below or drag connections.

 

regards,

Gordon Goodell

 

From: Jason Christensen [mailto:jason(--nospam--at)wcaeng.com]
Sent: Tuesday, February 17, 2009 9:16 AM
To: seaint(--nospam--at)seaint.org
Subject: Wind loads: ASD or Strength?

 

I gave a peer review a few weeks ago. I called the engineer for designing a wall stud for seismic loads only, from his calculations the C&C wind loads were about 10psf higher than the seismic.

The response I got was a bit perplexing. He said that the wind load (ASCE 7-05), using the MWFRS load not the C&C for OOP, was a strength level load and he then divided the MWFRS load by 1.4 and showed that that load was less than his seismic load.

I want to correct him on stating that the wind load is strength level, as well as using MWFRS in lieu of C&C for OOP. Does anyone know where, other than looking at the load combinations, that the code states that the wind loads from ASCE 7-05 are service level? For the use of the C&C loads for OOP I am going to refer him to the book "Guide to the Use of the Wind Load Provisions of ASCE 7".


Jason Christensen, S.E.
 
WCA Structural Engineering, Inc.
442 North Main Street
Bountiful, Utah 84010
PH. (801)298-1118
E-MAIL: jason(--nospam--at)wcaeng.com



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