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Re: Question on "Seismic Zone Factor" (Z

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Roger, thanks for the follow-up.

When I was on the SEAOC Seismology Committee in the mid 1980's, and it was
doing zones for the 88 UBC, I recall a rep from SEAOA appearing and asking
that the proposed eastern edge of Zone 4 in SE Calif swerve into AZ so as to
include Yuma. He stated a reasonable basis for that and it was done.

The San Diego delegates held out for Zone 3 for their locality, as before,
when there was sentiment among others to change it to zone 4.

Calif's Central Valley and northward was slated to drop back to Zone 2 (2B)
for 1988, but delegates in this area maneuvered to restore Zone 3. I was one
of the ringleaders in that; we had to take the matter to the SEAOC Board and
trump Seismology there. Language in ATC3-06 was cited in justification.

Currently there is a move to lobby the CA Bldg Stds Commission to overrule
the 2000 IBC and raise the zone-replacing "seismic design category" in the
same territory in North-central CA to the equiv of zone 3. Locally, many of
us oppose that because it would also impose the arbitrary 2:1 aspect ratio
for plywood shear walls, which we regard as technically bogus and a stupid
remedy that fails benefit/cost considerations.

At least there was a convenient Zone 2A on the shelf for the Hawaii people
to use when their research showed the shoe fit. And it fit the political
sentiments in your locale, much as it did east of the Rockies, to good effect.

All the noise that's made for changing codes, both in flyspeck minutiae and
in basic format --all for the sake of calling them "more rational"-- what a
joke. Like "patriotism" in affairs of state, "rationality" should be
regarded as the last refuge of disingenuous policycymakers. All sorts of
motives are at play in codework, and professionalism counsels to be candid
about them, as you have been.

Charles O. Greenlaw SE  Sacramento CA