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Re: Determining Rho with a mixed system

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Dennis-
    I wouldn't recommend violating the code thinking I could explain the
violation away later.  It just isn't worth the risk.  I'd figure the deck into
the story shear load, use the rigid diaphragm analysis, ignore the contribution
of your columns, make the other walls carry the extra load, and just avoid the R
= 2.2 problem altogether. Alternately, stick a moment frame out there. My
objective is to make conservative enough assumptions to cover my ass, simplify
the analysis where I can, and meet the design intent of the code.
    Likewise, I wouldn't intentionally violate the 2:1 limit for wood shearwalls
(even if you think you can make an accurate deflection calculation.)  Given the
uncertainties in the tie down deflection calculation, I wouldn't bet my license
on it.  The consequences for you are potentially a lot worse than for the
architect who has to add a few more inches to his wall width.  If the owner
wants narrower walls, he can always pay for moment frames or a proprietary
system.
    Chuck Utzman