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Re: Determining Rho with a mixed system

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Bill-
    You're right.  What I had be seeing is the fact that, in a system with
varying wall lengths, rho does penalize the use of short walls.  If  a system
is all 4' walls (unlikely) it doesn't make a difference.  However, if you
compare the relative stiffness of a pair of 4' walls to an 8' wall(rigid
diaphragm analysis) the 8' wall stress goes up substantially because the short
walls are so soft.  Breaking an 8' wall into two 4' walls in effect, penalizes,
the system.
    I still think that's appropriate.  It looks like stiffness is  proportional
to length from 6' on up, but from 6' on down things aren't so proportional. I
also think similar problems occur when stacked walls jack up the post and tie
down loads/deflections.
    As to the practice of ignoring the stiffening contribution of finishes, the
labs results I've seen show an early stiffness increase but under cycled
loading GWB looses strength and stiffness pretty fast.  Current practice seems
reasonable (and conservative).  It's even more true when the walls are short.
Chuck Utzman