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Re: Plywood Shearwals & Elevated Conc Piers

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This is a typical situation where engineering judgment is put to rest by the 
letter of the code. I would approach this in a couple of ways:
1. I could argue that the Aspect ratio is irrelevent if I could show that the 
panel is stiff enough to deflect less than the allowable 0.005 times the 
story height. Of course, this would require a wall deflection analysis. 
2. If there are windows and doors on either side of the shear panels, I would 
consider sheathing above and below openings and strapping the headers and 
sills to the shearwalls so as to reduce the panels effective height. However, 
make sure you can accumulate the shear in the drag panels above the windows 
and doors.
3. Raising the curb height is an option but don't disregard your foundation 
width and depth to reisist overturning if the panel is highly loaded. This is 
often overlooked.
4. Consider a proprietary panel like the Hardy Frame or the Hardy Panel (an 
18" wide x 10' max braced frame panel). 

These should help to overcome the code restrictions, but I think that it 
comes down to haveing the latitude to use engineering creative judgments to 
prove your design.

Dennis S. Wish PE

In a message dated 6/12/99 4:36:56 PM Pacific Daylight Time, 
Paul_Reilly(--nospam--at) writes:

 A light-frame structure, with plywood shearwalls, does not have sufficient
 lengths of tributary shearwalls (Li), within the 'wall-line' being 
 to comply with the prescribed height/length ratios for plywood shear walls.
 May the bases of the Li be elevated above the finish floor to attain the 
 height/length ratio?   If so, must all Li within the wall-line be the same?
 Thanks in advance >>