/ '| From the Desk ()_________)
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(__) Dennis S. Wish PE
I became concerned by the nature of the thread on Rigid Diaphragm Analysis
that we have created an issue of liability that could be used by any lawyer
to institute a suit, which may be friviolous, but can be justified by an
expert witness because of the lack of compliance to rigid diaphragm analysis
as noted in the 1994 UBC. It does not matter what the target of the suit is,
as long as the attorney include the lack of compliance to this methodology.
One engineer advised me that there is a standard of engineering practice that
is based upon the practice of the majority of engineers in that geographic
area. However, another engineer with extensive work as an expert witness
informed me that this is not so. He believes that if the method is prescribed
in the code, non-conformance for what ever reason is sufficient to support a
liability claim against the EOR.
If this is true, those engineers in Seismic Zone 3 and 4 may find themselves
suseptable to greater liability if they ignored rigid diaphragm analysis and
arbitrarily (or by standard practice) designed using flexible diaphragm
methods where rigid diaphragm may have otherwise governed.
Again, if this is true, our protect should come in the form of a position
statement from our professional organization (SEAOC or SEAOSC) which
justifies the use of flexible diaphragm design for lack of suffient design
examples or deflection criteria for unblocked, flexible diaphragms.
I believe that we all need to write to the California state chapter of SEA or
at least to SEAOSC to alert them of our concerns and ask that they protect
their members by issuing a position statment acknowledging the acceptance for
flexible diaphragm design for the life of the 94 UBC and related Local Codes.
I would appreciate any comments or suggestions from those who agree, disagree
or those who have suggestions on how to accomplish this. I am forwarding a
copy of this email to seaosc(--nospam--at)aol.com and seaoc(--nospam--at)aol.com.
Dennis S. Wish, PE
Dennis S. Wish PE
Structural Engineering Consultant