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RE: Residential Design Discussions

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Gerard,

I would suggest that the "lean" be placed toward them being unable to
remove it.  There are two reasons that I think/suggestion this.

One deals with the current legal code in force in California, which is the
1997 UBC code.  SEAOC does not have the power actually change that code,
only the state government does.  SEAOC could certainly attempt to get the
state legislature or commission (or who ever in the state officially
handles the California Building Code) to make the change, but they are
just as powerless to actually make the change in the currently enforcable
code as you are.  What they can do is make changes (or try to...see the
second reason) to future editions of the model building codes that then
the state government may or may not adopt.  Having said all that, it is
certainly possible that they are not bringing the full pressure to bear on
the state government to make the changes that they could actually bring to
bear.  If so, then by all means pile on.

The second reason is that while the SEAOC Seismiology committee is still
influential and somewaht powerful in the seismic design world, they are no
longer the center of the seismic design universe.  In the past, the SEAOC
Blue Book would become the seismic provisions in the UBC.  This is no
longer true.  The seismic provisions of the IBC and NFPA 5000 will come by
way of NEHRP and ASCE 7's Seismic Task group (as well as AISC for steel
provisions, ACI for concrete provisions, and ACI/ASCE/TMS for masonry
provisions.  While many of the members of the SEAOC seismology committee
are involved in both NEHRP and ASCE 7, SEAOC no longer controls the code
development process of the seismic design provisions.  Thus, there are
bound to be things that SEAOC Seismology may want that does not make it
into the model building codes.

My point was that while SEAOC may be able to do more (or even do
something), the more likely avenue to get something changed is to realize
that the state government of California really holds the cards when it
comes to the Rho issue.

HTH,

Scott
Ypsilanti, MI


On Thu, 26 Sep 2002, Gerard Madden, PE wrote:

> Scott,
>
> I have the meeting minutes from Seismology committee meetings, they have
> definitely looked at it and know it needs changing, but they are either
> Unable or unwilling to REMOVE it from the code, let alone cap 10/lw<=1.
> Some want significant change, some want no change. Unfortunately, I
> don't think they post the meeting minutes anymore for us to see. It has
> been 5 years that this has been in the code, and 2 years since Gary
> Searer's paper was delivered.
>
> I think they are unwilling to touch it because those that created it
> didn't think it through enough as Gary Searer proved. Too much emphasis
> is given to RHO when determining seismic forces. The IBC has made slight
> improvements to the RHO, but here in CA, we can't use it yet nor does
> there seem to be a light at the end of the tunnel saying we will ever.
>
> Rho should not have ever been introduced into the code, let alone have
> the potential to raise design forced by 50% because I have a short
> shearwall yet I could have a mass irregularity or soft story and just do
> a dynamic analysis and not be subject to the penalty.
>
> It is an idea with definite merit and I'm sure developed with the best
> intentions, but I am sure it was a mistake to put it in the 97 UBC.
>
> -gerard
> Santa Clara, CA
>
>
>
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