# Re: rho - light frame timber construction

• To: seaint(--nospam--at)seaint.org
• Subject: Re: rho - light frame timber construction
• From: Byainc(--nospam--at)AOL.COM
• Date: Thu, 17 Jun 1999 22:48:05 EDT
```In a message dated 6/17/99 6:53:40 PM Pacific Daylight Time, pfr(--nospam--at)pacbell.net
writes:

<< 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. >>

(B.Y)I am not sure how you are coming up with this interpretation. But r_max
is the ratio of the lateral load in the wall carrying the largest portion of
the shear at the level under consideration, to the total base shear at that
level, multiplied by (10/length of that wall). Please refer to the 4th
paragraph of section 1630.1.1.

For example assume the wall resisting the most lateral load in a story is
carrying 3000 lb, and is 7 feet long. The total shear at that story is 10,000
lb. then:

r_max = (3000/10000)(10/7) = 0.43

Ben Yousefi, SE
San Jose, CA

```