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# Re: Concrete Shearwall Load Combination Question

• To: seaint(--nospam--at)seaint.org
• Subject: Re: Concrete Shearwall Load Combination Question
• From: "Gerard Madden, SE" <gmse4603(--nospam--at)gmail.com>
• Date: Mon, 22 Jun 2009 10:32:31 -0700

Brian,

Check with Ben or his website. Sometimes there are typos and things and he issues a very thorough errata...I'm assuming the code changes are in the new review guide.

-gm

On Mon, Jun 22, 2009 at 6:37 AM, Brian S Bossley wrote:

Gentlemen -

I am currently studying for the California SE-III and came across a load combination that I was unfamiliar with.  I am looking over Ben Yousefi’s review manual for a design problem for a special reinforced concrete shearwall in SDC D.

The generic load combination goes from  (1.2+0.2Sds)D+rho*Qe+0.5L  & (0.9-0.2Sds)D+rho*Qe, where Sds =1.0, rho = 1.3

to  1.4D+1.3Qe+0.5L                        &  0.7D+1.3Qe

and then  1.46D+1.1Eh+0.5L                           &  0.63D+1.1Eh

Qe = rho*Qe, so really I think that the second set of equations should be 1.4D+1.3Eh+0.5L &  0.7D+1.3Eh, but I am totally baffled as to how you get from the second set of equations to the third.  I can’t find any reference that points to increasing/ reducing the dead load and increasing the seismic loads by different factors.

What am I missing?

Brian S Bossley, P.E.

7610 Olentangy River Rd

Columbus, OH 43235

(614) 847-1110 x 121 (ph)

(614) 847-1116  (fax)