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RE: Interior wood shear wall lateral bracing

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Jeff,

 

The lateral bracing the plan reviewer is asking for is for the out-of-plane stability of the shear wall for the in-plane shear force the wall is going to be subjected to. Just like the bracing you said you’d require for moment frames. The minimum 5 psf requirement is not the same as bracing requirements and it is for the out-of-plane lateral loads a wall is subjected to. I don’t know if there is a procedure to calculate the lateral bracing force for the in-plane loads like in moment frames. Normally, 4 ft on center bracing to the diaphragm is adequate and acceptable for wood shearwalls.

 

Oshin Tosounian, S.E.


From: Jeff Hedman [mailto:jeff_h(--nospam--at)lrpope.com]
Sent: Wednesday, December 07, 2011 8:55 AM
To: seaint(--nospam--at)seaint.org
Subject: Interior wood shear wall lateral bracing

 

I have a small, wood framed commercial building that has an interior shear wall (10'-0" tall) that is parallel with a roof truss and directly underneath it.  I have a plan reviewer that is asking for lateral bracing on top of the wall, similar to gable end wall bracing.  We usually have not provided this for short, wood framed interior walls. Our reason being that the lateral load at the top of the wall is only 5 psf*10 ft/2 = 25 plf.  Very low loads.  The truss manufacturer states that the truss must be braced with purlins at some spacing or directly applied ceiling in order to keep the trusses plumb.  We are in a seismic design category D, so we generally do not rely on sheetrock for anything.  However, if this is enough bracing for the trusses to stay plumb, we have generally considered the truss braced.  Since our wall is attached to the truss it is also braced.  What does everyone else do?  All I know at this point is over the past 12 years, I have never seen this type of lateral bracing in construction, nor have I been asked for it on commercial buildings that we have done in the past.  Perhaps this is a short coming of local construction practices.  For masonry or concrete shear walls and moment frames we require bracing.  My question is specifically for short wood framed shear walls. If it should be there, I have no problem with requiring it, but I don't want to back down on this if it is not required.

 

Jeff