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Re: Philosophy: Seismic Design Standards

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Mike:

Personally, I need time to absorb all of the recent (1997 UBC) and near future
(2000 IBC) design changes.  Unless we get another major earthquake that
indicates a glaring area of weakness in our knowledge, I would like the next 10
years to be devoted to simplifying what we have, correcting errata, design
example manuals, and better enforcement of those seismic design standards that
presently exist.

Rick Drake, SE
Fluor Daniel, Aliso Viejo

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"Mike Valley" <mtv(--nospam--at)skilling.com> on 01/17/2000 12:03:03 PM

Please respond to seaint(--nospam--at)seaint.org

To:   seaint(--nospam--at)seaint.org
cc:    (bcc: Rick Drake/AV/FD/FluorCorp)

Subject:  Philosophy: Seismic Design Standards



Introduction:

We are standing at an important crossroads in terms of seismic design
standards.  Nearly every important U.S. standard that affects
seismic-related portions of the design and construction of buildings (and
some other structures) has just completed a development cycle.  There is an
overwhelming consensus among those who are involved in the various aspects
of the process that now is the time to regroup and plan the near future
(perhaps 10 or more years) of seismic design standards in this country.  I
won't pretend to represent the parties involved.  However, many of the
participants in the formal process subscribe to this listservice.  I believe
that your consideration and input may help to guide the process.

Many of the participants on this listservice could write volumes on this
topic.  However, I would suggest that you provide only a brief outline of
your fundamental philosophy on this topic; please don't provide a laundry
list of code items that need to be fixed.  Please keep in mind that the
underlying philosophy is the topic of this thread and that brief comments
are more likely to be read (and thus have a better chance of being
implemented).

Please comment on how you believe that things should be done.  Then, if you
believe that it is impossible for the code development process to achieve
this end, feel free to comment on what you feel must be done at a minimum.

================
Substance:

To what extent should seismic design standards:
a) Simply codify prevalent practice?
b) Codify current approaches with some improvements (i.e., be consistent
with current practice with some changes to address how things SHOULD be
done)?
c) Be founded on first principles (a "rigorous" approach) versus observed
performance (an "anecdotal" approach; recognizing that the two are not
always easily reconciled)?
d) Reflect the current state-of-the-art (recognizing that this can be a
rapidly moving target)?

I would suggest that several important items which affect the approach taken
may include: applicability to geographically diverse moderate and high
seismic areas; evaluation and rehabilitation of existing structures versus
design of new structures; various sizes and styles of construction (from
residential wood frame to long-span or high-rise steel or concrete
construction); various levels of engineering sophistication; material- or
system-specific behavior; life safety versus economic recovery; prescriptive
requirements in legally binding standards versus an outline of design
philosophy in voluntary guidelines.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Michael Valley, P.E., S.E.                       E-mail: mtv(--nospam--at)skilling.com
Skilling Ward Magnusson Barkshire Inc.                  Tel:(206)292-1200
1301 Fifth Ave, #3200,  Seattle  WA 98101-2699          Fax:        -1201