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RE: IBC and Rho factor

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Gerard makes many valid points. I have known your experience in the past
to try and simplify the complexities of the codes that even you admit
were wrong (or you had in the past) and I admire you tremendously for
your efforts.
Gary Searer made an excellent argument against Rho and because the
results were conservative and because S.K. Ghosh in Illinois believed
that by maintaining the requirement of Rho at 1.5 in residential
construction would "force" or "encourage" (either word is equally
insulting to me as a licensed professional) to design properly, the
Seismology Committee decided it would take no further action on the
issue of Rho.

Adding to Gerard's comments; Try comparing a two story conventional
construction project to the same building designed to engineered
standards. Where is the incentive to design by engineering standards in
order to improve the performance of the home and how do you educate the
public on the difference? Whose responsibility is this?

Finally, why widen the gap between design methods when you do not serve
the public's interest but simply avoid the strength of the lobbiest and
allow each to follow their own design belief. The bottom line is that
the public suffers, we lose much of our livelihood because compliance to
the building code encourages incentives for developers to simplify their
design and avoid engineering.

I'm not arguing that conventional construction doesn't work, only that
it doesn't work as well as engineered designs. The public should have
the right to make the decision as to how they want their homes to
perform because they become responsible for the cost of repair. If we
have multiple codes - one less restrictive than the other - we need
disclosure laws to educate the homebuyer as to why they need to by a
Sunrise home verse Joe Schmoes custom home. Is either better or does one
simply profit more?

Dennis S. Wish, PE

-----Original Message-----
From: Yousefi, Ben [mailto:Ben.Yousefi(--nospam--at)] 
Sent: Tuesday, October 01, 2002 1:58 PM
To: 'seaint(--nospam--at)'
Subject: RE: IBC and Rho factor


A point of clarification here. The limitation of Rho to 1.0 for light
frame shear walls was actually approved to the be incorporated to the
2003 IBC in April of 2000. Long before ASCE 7 incorporated it per your
email. The proposal was submitted by the SEAOC Seismology. It intended
to include the concrete and masonry shear walls also. However, Dr.
Ghosh, rightfully in my opinion, spoke against extending it to those
types of walls. (what good is a 4 ft concrete shear wall anyway?!)

On a side note:

The change has also been approved by the LA Basin Regional code Group
and will be adopted by ordinance throughout southern California
jurisdictions. We took up the same issue in our Tri-chapter (Bay area)
code committee. Most didn't think this is a real issue in residential
(or light frame) construction anyway, since you normally have many shear
walls and most are lightly loaded. We even asked our Plan check staff to
see if this is a major point of contention with designers, and all
indications were that it is not. And, some of the committee members were
of opinion that it is not such as bad idea to penalize short walls even
in light frame constrion.

Ben Yousefi, SE
San Jose, CA

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