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# RE: Determining Rho with a mixed system

• To: <seaint(--nospam--at)seaint.org>
• Subject: RE: Determining Rho with a mixed system
• From: "Bill Allen" <Bill(--nospam--at)AllenDesigns.com>
• Date: Wed, 18 Aug 1999 18:46:03 -0700

```Yes, Chuck, I'm aware of how the Code reads in this particular section,
degree of complexity not withstanding. I am only trying to highlight that
the way the wording in this section came out in the final print is not
exactly how the original author, Dick Phillips intended it. He said as much
at the seminar in Alhambra and (I hope) something in writing will be
forthcoming from SEAOC shortly.

FWIW, it doesn't work so nicely for short shear walls. This penalty was
unintentional and will be/should be corrected. Currently V in Lw divided by
Lw is fv. All you have to do is look for fv(max) multiply it by 10 and
divide by the story shear to determine "r sub i". So, fv (max) really
determines rho, not the actual redundancy of the structure. Again, this was
not the intent of the author.

To: John Shipp-
Can you (pretty please) talk to Dick Phillips and have him (or someone from
the seismology committee) write a clarification to this 10/Lw issue so that
we can post it on the 'Net?

Regards,

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

> -----Original Message-----
> From: chuckuc [mailto:chuckuc(--nospam--at)dnai.com]
> Sent: Wednesday, August 18, 1999 6:30 PM
> To: seaint(--nospam--at)seaint.org
> Subject: Re: Determining Rho with a mixed system
>
>
> Bill-
> IMHO you're making something complicated out something very
> simple. Ri max. =
> the maximum value of (10/ Lw) x (the shear load in Lw/the
> total story shear at
> that level). That's the way the code reads and it works
> nicely.  It has nothing
> to do with counting the number of 10 foot walls (which
> doesn't work well at
> all).
> Chuck Utzman
>
>
>

```