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Re: 2003 IEBC vs 1997 UCBC URM shear wall capacity

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Taking a guess since I am not familiar with either, but here goes...  I beleive the UCBC eqn is for working stress loads, while the IEBC eqn is for factored load combinations.  That would explain the 0.5 vs. 0.9...
In previous URM retrofits under '94 UCBC, I remember using 1/2 of the wall pier weight for rocking resistance.  It gave reasonable values without being overly conservative.

David A. Topete, S.E.

Wildman & Morris
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San Francisco, CA 94105
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"Marc Mitchell" <mitchell.marc(--nospam--at)>

11/01/2006 11:59 AM

Please respond to

2003 IEBC vs 1997 UCBC URM shear wall capacity

Why is the equation for rocking shear capacity Vr = 0.5*PD*D/H in the UCBC and Vr = 0.9*PD*D/H in the IEBC?  From a statics standpoint the UCBC is the correct formula, isn't it?  Also PD is defined in both as "...dead load at the top of the pier under consideration..."  Why wouldn't you use the self weight of the wall acting at the centroid to resist rocking as well?
Marc Mitchell