Friday, July 13, 2007

RE: Wood interior wall studs

I approach the design of interior walls essentially the same way, however although the 5 psf lateral is not defined as wind or seismic, I believe that it is rational to consider this lateral load to be generally of short duration and I use a load duration factor Cd of 1.6 for the design case with the 5 psf lateral load.

Albert J. Meyer, Jr., P.E.
Project Engineer
ameyer@cagleyharman.com
Cagley Harman & Associates, Inc.
Structural Engineers & Parking Consultants
900 West Valley Forge Road, Suite 200
King of Prussia, PA 19406
610.337.3360 vc
610.337.3359 fx

www.cagleyharman.com


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From: Mark Deardorff [mailto:mark@rstavares.com]
Sent: Fri 7/13/2007 1:46 PM
To: seaint@seaint.org
Subject: RE: Wood interior wall studs

The load combinations in 1612.3.1 and 1612.3.2 require including the floor and roof live loads. Since the 5 psf load is not a wind or seismic load it should probably all be concurrent as conservative as that sounds.

Mark E. Deardorff, SE
R & S Tavares Associates, Inc
9815 Carroll Canyon Road
Suite 206
San Diego, CA 92131
Phone: 858-444-3344
Phone: 209-863-8928
Cell: 209-765-5592
mark@rstavares.com <mailto:mark@rstavares.com>

www.rstavares.com <http://www.rstavares.com/>

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________________________________

From: David Topete [mailto:dtopete@gfdseng.com]
Sent: Friday, July 13, 2007 10:40 AM
To: seaint@seaint.org
Subject: RE: Wood interior wall studs

Are you being overly conservative by designing for both floor live load and roof live load concurrent? Also, silly question, but are you checking a load combo at strength level, and using working stress design for the wood?

David A. Topete, SE

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From: Andy Heigley [mailto:aheigley@jgaeng.com]
Sent: Friday, July 13, 2007 10:32 AM
To: Seaint
Subject: Wood interior wall studs

Hello all:

I just want to get some feedback from other engineers about designing interior load-bearing wood wall studs. When designing the walls, I normally check two load combinations:

1) DL + LL +LLr

2) DL +0.75LL + 0.75LLr + 0.75W (with W = 5.0 psf interior horizontal partition load; I typically use a Cd=1.0 if I am just supporting floor live and dead load. And a Cd=1.15 when carrying roof loads in addition to the floor live and dead loads. I think the use of Cd=1.6 seems less conservative when you are dealing with large axial loads, particularly in a multi-story buildng.)

A contractor is battling me over some stud sizes b/c the stud height is about 10'-0" and for 2x4's once you add the horizontal loading, in the second combination above, it significantly reduces the axial capacity. His engineer doesn't check the second loading listed above.

I just want to get some other people's opinion on what they check in your own design.

Thanks,

Andrew Heigley, PE

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