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
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
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,
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 >>