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[SEAOC] Re: [SEAOC] Plywood Shearwall Deflection

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Dennis,

>From what I read, it would be more appropriate to call your system a wood
frame. The two shearwalls acting as columns, and the connection above the
door header acting as a beam.

Now, the question is, will this frame work? I don't think so. Primarily
because you can not accomplish a moment connection in wood members. A pin
frame will not work.

I recommend that you look at the whole wall. Consider moving the door such
that you get at least one shear panel that meets the h/d requirements.

Hope that helps.

Shafat




>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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