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Re: Hold downs with "Perforated Shear Wall Method" and "Force Transfer Method"

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See IBC 2305.3.8.4:
2305.3.8.2.4 Uplift anchorage at perforated shear wall ends. Anchorage for uplift forces due to overturning shall be provided at each end of the perforated shear wall. The uplift anchorage shall conform to the requirements of Section 2305.3.7, except that for each story the minimum tension chord uplift force, T, shall be calculated in accordance with the following:
T=(Vh)/(Co Σ Li)	(Equation 23-3)

Also, the Wood Frame Construction Manual 2.2.4 states: "Resistance to overturning shall be provided. The resisting dead load moment shall be calculated using no more than 60% of the design dead load." WFCM 2.2.4.1 goes on to say: "Hold downs used to resist both uplift and overturning shall be designed to resist the sum of the forces..." This could apply to both the segmented and perforated shear wall method in the WFCM.

One caveat however, the WFCM does not use dead load to offset uplift and use the same dead load again to offset overturning (double-dipping). So in the WFCM tables, we only show dead load offsetting uplift loads.

I am not familiar enough with the force transfer method to comment on that.

HTH

Buddy

John "Buddy" Showalter, P.E. 
Director, Technical Media 
AF&PA/American Wood Council 
1111 19th Street, NW, Suite 800 
Washington, DC 20036 
P: 202-463-2769 
F: 202-463-2791 
http://www.awc.org 

The American Wood Council (AWC) is the wood products division of the American Forest & Paper Association (AF&PA). AWC develops internationally recognized standards for wood design and construction. Its efforts with building codes and standards, engineering and research, and technology transfer ensure proper application for engineered and traditional wood products.

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The guidance provided herein is not a formal interpretation of any AF&PA standard.  Interpretations of AF&PA standards are only available through a formal process outlined in AF&PA's standards development procedures.

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From: "Will Haynes" <gtg740p(--nospam--at)gmail.com>
To: seaint(--nospam--at)seaint.org
Subject: Re: Hold downs with "Perforated Shear Wall Method" and "Force Transfer Method"

2305.3.7 appears to address it to me. I have used the dead load (reduced per the combinations) before to resist overturning on wood shear walls with openings but I couldn't find a specific example representing that. It would be strange for any method to completely ignore statics and always require hold downs for wall segments.



On Thu, May 22, 2008 at 8:18 PM, Joseph R. Grill <jrgrill(--nospam--at)cableone.net> wrote:
> In reading the IBC for the "Perforated Shear Wall" method of design it 
> there are formulas for the required uplift force at the ends of the 
> walls. Section 2305.3.7 (before the design calculations for the 
> method) suggests that the hold down requirements can be reduced due to 
> the dead load on the wall as in traditional shear wall design.  Is 
> this true.  And if so, I would assume that the same is true in using 
> the "Force Transfer Around Openings" method.  Yes?  Examples and 
> documents that I have for the perforated method only show the basic 
> calculations, but don't respond to any DL that may be present.
>
>
>
> Thanks,
>
> Joe

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