From: "Sprague, Harold O." <SpragueHO(--nospam--at)bv.com>
Date: Thu, 8 Feb 2001 13:29:40 -0600
You are correct. In your assessment. Currently, I chair one of the
technical subcommittees and I am a member of the Provisions Update Committee
(PUC) of the BSSC that develops the NEHRP Provisions.
Many of the people involved on the SEAOC Seismology Council are also
involved in the development of the NEHRP Provisions. The 1997 UBC was an
incremental step toward the NEHRP Provisions which are codified and
contained in the 2000 IBC and the ASCE 7. The big issue with NEHRP was the
new maps and the disappearance of zones which did not happen in the 1997
UBC. Since there are no zones the zone triggers had to be modified in the
NEHRP. Some of the Blue Book / 1997 UBC was developed as a result of the
NEHRP, and some was developed within the SEAOC Seismology Committee. For a
full list of those who are seated at the NEHRP table, you might want to look
at the list in the back of the NEHRP Provisions.
There are some academics participating in the NEHRP process, but the
majority of the participants in the PUC and Technical Subcommittees are
practitioners. SEAOC in its various California and other state domains have
votes and input, but the development process has evolved to rely on a more
national, broad based constituency.
One of the issues that was discussed informally recently was complexity. It
is a sincere concern that the code is getting very complex, but provisions
are only added when there is a perceived and demonstrable need. Some of
code gets added when it is pointed out that engineers are interpreting the
code as a lawyer as opposed to as an engineer. Intent of the code can be
determined by looking at the commentary, but it is seldom done in practice.
I have had this argument even within my own company.
Lateral Drift issue:
This thread started with a discussion by Gerard Madden on the differences
between the 1994 and 1997 UBC invoking equation 30-6 in the UBC-97. I sat
in on an informal discussion on the issue with 2 of the members of the
seismology committee that created this section. And the issue focused on a
review of a tall building in San Diego. I don't want to betray any
confidence, but suffice it to say that the 1997 UBC has a problem in this
area. It is a major issue to fix it, but it will be fixed.
I am just a foot soldier in the code development community. The
participants who really know what they are talking about (I fake it) share
the concerns expressed on this forum. The participants see the warts, and
try to fix them. Sometimes the fix adds complexity, and creates its own
warts. But I assure you that the concerns for simplicity and accuracy are
shared by my BSSC colleagues.
Hopefully, now that the impetus for seismic code development is unified and
contained in the NEHRP and ASCE 7 processes, the effort will be more
efficient and responsive. Seismic code provides no value if it can not be
understood by the practitioners. By the same token, it is incumbent on the
practitioners to not only use the code, but to review the commentary and
background in order to understand the intent.
Harold O. Sprague
Retired Iron Worker
Mediocre Seismic Guy
> -----Original Message-----
> From: Scott Maxwell [SMTP:smaxwell(--nospam--at)engin.umich.edu]
> Sent: Thursday, February 08, 2001 12:18 PM
> To: seaint(--nospam--at)seaint.org
> Subject: RE: seismology committee
> I won't step into the debate of the use of the term "bashing", but I will
> reinforce Martin's point about extend of the "power" of SEAOC's Seismology
> committee. I think that it is unfair to lump all the critizism of the
> seismic code at SEAOC's Seismology committee. From what I understand,
> with the advent of the NEHRP provisions and the adoption of those
> provisions into the model codes, the SEAOC Seismology has lost much of it
> past power.
> Keep in mind that in the past the UBC seismic portions WAS the SEAOC Blue
> Book. This is no longer the case with the IBC and was never the case with
> the BOCA and SBBC codes. From my understanding, the seismic code of today
> and the future is a product of NEHRP which is a product of the BSSC
> committees. I am sure that at least some of the SEAOC Seismology
> committee members are also participants in the BSSC process, especially
> since California IS still one of, if not the most, earthquake aware states
> in the country.