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# RE: RE: Determining Rho with a mixed system

• To: <seaint(--nospam--at)seaint.org>
• Subject: RE: RE: Determining Rho with a mixed system
• From: "Bill Allen" <Bill(--nospam--at)AllenDesigns.com>
• Date: Tue, 17 Aug 1999 22:01:44 -0700

```>From my understanding (I sure wish Dick Phillips would jump in here
somewhere), a building with one 40 ft. shear wall is equivalent in redunancy
to four 10 ft. walls. Comparing this to a building with say, four, ten foot
shear walls, it would be no less redundant. However, if you were just
counting shear walls, the building with the four ten foot shear walls would
be significantly more redundant than a building with one 40 ft. shear wall
which is what the author was trying to avoid. I believe somewhere close to a
correct interpretation of redunancy ("r sub i") is to look at the shear
force in a shear resisting element and then divide that by the total shear
force at that level in a particular direction. However, if one of those
shear elements was a shear wall greater than 10 ft. long, for the purposes
of the redunancy calculation, this wall should be broken up into sections of
10 ft. shear walls as not to penalize long shear walls.

After reading the above a couple of times, I'm not convinced I clarified
anything :o(.

Of course, we haven't talked about the redundancy effects of a "wall frame"
or a perforated shear wall yet, have we?

If someone wants to do some examples and fax (@ 949-249-2297) or e-mail them
to me, I can scan and post them on my web site so we can all throw darts at
it. I think that's the only way I'm going to figure things out, like the
shear wall deflection I put up a few days ago.

Regards,

Bill Allen, S.E.
ALLEN DESIGNS
Laguna Niguel, CA

> -----Original Message-----
> From: Rhkratzse(--nospam--at)aol.com [mailto:Rhkratzse(--nospam--at)aol.com]
> Sent: Tuesday, August 17, 1999 9:39 PM
> To: Bill(--nospam--at)allendesigns.com; seaint(--nospam--at)seaint.org
> Subject: Re: RE: Determining Rho with a mixed system
>
>
> In a message dated 8/17/99 6:12:00 AM, Bill(--nospam--at)AllenDesigns.com writes:
>
> >According to Dick
> >Phillips, the 10/lw was ONLY intended to "help" long walls but NOT to
> >"penalize" short walls.
>
> This fine distinction is not entirely clear to me.
>
> Ralph Hueston Kratz, S.E.
> Richmond CA
>
>

```