Mr. Shipp's letter expressed many of my own thoughts and beliefs in terms of
the rigid-flexible diaphragm problem.
Especially in residential construction, we are dealing with too many
components participating in the lateral resistance and in the structural
performance of the diaphragms. With that many unknowns, we will never know
exactly what kind of the diaphragm rigidity we are dealing with. Hence, the
analysis of "extremes" seems to be a logical way to determine the "worst
case" scenario and to design a safe structure.
Indeed, residential wood-frame structures had performed well during the 1992
and 1994 earthquakes. Unfortunately, we would never know, was it due to the
adequacy of the engineering approach, or to the sky-high ultimate/allowable
ratio of wood, or to a considerable redundancy of such structures.
Can we, at that point, say "it ain't broken", and keep using the
"traditional" approach? Sure, we can. Should we say and do that?
Apparently, the consensus between those who have the desire, ability,
knowledge, and time to participate in the code development is "no, we should
As a practicing consulting engineer, I do not like "them" changing
(especially, sharply changing) the building code. Those changes divert sooo
much time to understand and implement (think about the "in-house-developed"
Yet still, those changes seem imperative, and it looks like we have to
accept them. Unless, of course, the issue (unlike the subject one)is
something totally outrageous. But for that very purpose we have OPEN
discussions BEFORE the final approval of the code. As far as I am concerned,
the system appears to be logical and working. That system may not be
perfect, but it is definitely the best available.
Mr. Shipp, your ideas (and the latest e-mail letter) are very PROFESSIONAL,
knowledgeable, educational, and, in general, greatly beneficial to the
engineering community and to the public we serve.
Please accept my professional gratitude and support for your work.
Vyacheslav "Steve" Gordin, S.E.
Get Free Email and Do More On The Web. Visit http://www.msn.com