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RE: IBC "Oops" (Was Residential Design Discussion)

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I have looked at the IBC 2002 committee changes on the ICBO website. It
appears that the 10/lw<= 1.0 is being supported for LIGHT-FRAME
STRUCTURES. This is good, but still does not address many of the issues
that Gary Searer brought up in his paper. The 10/lw<=1.0 should be
applicable to all structural systems, as a 9 foot concrete shearwall is
still treated as less than a single structural element-again this wasn't
the intent of the code according to Mr. Hamburger's account.

I would like to thank the structural members of the ICC including Ben
Yousefi, Chris Tokas, John Hooper, and others who have experience in
seismic design and hopefully pushed for revisions to RHO. While I
personally would like to have seen it (Rho) removed in its entirety,
this is an important step. It sounds like ASCE-7 has yet to approve
this, so hopefully I'm not jumping the gun in having some cause to
celebrate. RHO would almost always be less than 1.0 now in a residential

Mr. Gary Searer deserves most of the credit on the RHO issue in
delivering a clear and concise account of how flawed this provision is.

To see the proposed changes here is the link:

The amendments of interest are S43-02 & S49-02.

Now we need to fix the UBC or get IBC 2002 approved in CA. If we can't
get the IBC approved, the dead UBC must be changed somehow.

It seems we are no further on rigid diaphragms...

Santa Clara, CA

-----Original Message-----
From: Allen Adams [mailto:aadams(--nospam--at)] 
Sent: Tuesday, October 01, 2002 11:38 AM
To: seaint(--nospam--at)
Subject: Re: IBC "Oops" (Was Residential Design Discussion)

One of Dennis Wish's core complaints in regard to this issue is the
that the rho factor inflicts on short walls. This problem HAS been
addressed and is in the process of resolution. The Draft copy of ASCE
defines rho for walls essentially the same as in UBC 97, but then adds:
"... where the ratio 10/lw need not be taken greater than 1.0 for
of light frame construction." Once ASCE 7-02 is formally approved, it
be incorporated into the IBC.

If California would adopt the IBC, the problem that Dennis has addressed
would soon go away. But it is now a political matter, not a technical
matter: rather than directing your ire at volunteers who work on the
committees, contact your California State Assemblyman and State Senator.
They are the only ones now who can solve the problem (by getting the
to adopt the IBC). There is not a mechanism in place to make changes to
UBC (ICBO will soon be absorbed into the ICC), and I doubt the State has
the will to finance a replacement (it seems that the State was getting a
free ride on Code development). We can yell 'til we are blue in the
but it seems obvious to me that the UBC isn't ever going to be changed
again, no matter how outrageous it might be. As long as California
to stay with the UBC, SEAOC is powerless - like eveyone else - to
the problems. So direct you energy to your Assemblyman and State Senator
tell them to support adoption of the IBC (you are wasting your time
them to support changes to the UBC - it isn't going to happen). The UBC
a dead horse. I'm not saying anything about how I thing things SHOULD
be, I
am only telling it like I see it.

But somebody did address the issue of the rho factor, and they did push
hard enough to get it approved in ASCE 7. Somebody worked within the
to correct a problem. I don't know who on the ASCE committee was behind
change; maybe it was even SEAOC members (my guess is that SEAOC had a
in it). Whoever it was, they should be thanked with as much energy as
expended previously criticizing them.

Allen Adams, S.E.
RAM International

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