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[SEAOC] Plywood Shearwall Deflection

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A friend that lives in Los Angels recently contacted me to see if I could
help him with this problem. I would like some input on the following
hypothetical problem:

The L.A. City building department increased the H/b ratio of 2:1 for
plywood shear panels - where, prior to the Northridge earthquake the ratio
was 3.5:1. The height of the panel was twelve feet from foundation to
lateral restraint at the roof diaphragm.  The design has a three foot
shear panel on either side of a four foot by seven foot door. The panels
don't make the 2:1 ratio required by the ordinance.
I responded by explaining that I thought you could exceed the 2:1 ratio if
you design the panel for deflection based upon the 1991 UBC standard. He
indicated that he did not feel comfortable with this based upon the
current ordinance. He further explained that as far as he knew, there was
no new testing on wall deflection.

Classically, the tow panels can be combined across the opening as long as
each pier is adequately anchored and braced. The question came as to how
to determine the deflection of the two piers when tied across the opening
and acting together.

Does anyone have a method for determining shear wall deflection with an
opening in the shear panel?

Dennis Wish PE

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