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RE: Perforated Shearwall Adjustment Factor reference

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In a draft 2000 NEHRP commentary, I got ahold of, it indicates the tables
are based on all unusable height being opening and all opening having the
same height of the maximum opening. Co in the tables is just the minimum of
1 or the sheathing capacity ratio F multiplied by the ratio of the total
length divided by the usable length.

r = 1/[1+[Ao/(H*sum(Li)]]  ===> F=r/[3-2*r]  ===> Co=min[1,F*L/sum(Li)]  

H=wall height
Ao=total opening based on max opening height times the total length of
unusuable wall and opening
L=total length
Li=length of individual usable segment

Try it with the rules above and see if the Co matches the table in the IBC.

Scott M Haan  P.E.
Plan Review Engineer
Building Safety Division, 
Development Services Department,
Municipality of Anchorage
phone: 907-343-8183   fax: 907-249-7399

> -----Original Message-----
> From:	David B Merrick [SMTP:mrkgp(--nospam--at)]
> Sent:	Tuesday, March 20, 2001 2:04 PM
> Subject:	Perforated Shearwall Adjustment Factor reference
> Where can I find the derivation of the values for the Perforated
> Shearwall Adjustment Factor. I had found a reference that calls out
> Douglas, Bradford K., and Sugiyama, H. 1995 Perforated Shearwall Design
> Approach. American Forest and Paper Association (AF&PA), Washington, DC.
> Has anyone reviewed this approach to assure that it is truly a
> conservative approach to short-cutting the perforated shearwall
> analysis?
> David Merrick, SE
> mrkgp(--nospam--at)