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rho - light frame timber construction

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Please help.  I am struggling to master the inclusion of rho in
consideration of light frame
timber construction.  For a simplied static case -

Site Seismic Criteria: [1630.2.3]  Zone 3:
V = (3Ca/R)(w)  = 3(0.36/5.5)w= 0.196w
Vmin = 0.11CaI/R)w  = 0.007w
Vmax = (2.5CaI/R)w  = 0.164w
VGross   = 0.164w
Light Frame Timber Construct., Plywood Shear Walls
Timber design per ASD, therefore:
Vdesign = VGross/1.4 = 0.164w/1.4 = 0.117w

For rho = 2-20/(r_max*sqrtA) and 1.0 < p < 1.5, I am using r_max =
(v_demand/v_allow)
where v_allow is the unit shear capacity of  the plywood shearwall that
would have been
specified for the unfactored (no-rho) unit shear demand.

Given that this interpretation of rho is correct... rho may then
factored against the calculated demand unit shear and controls the
selection of an appropriate sheathing and nailing configuration to
service the demand.

Advice greatly appreciated.

Paul Reilly, PE