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RE: Rho for diaphragms

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Because the INDIVIDUALS who work on the Codes, Blue Book, and Seismic Design
Manual are not the same (even though they may all represent SEAOC), there
are often subtle and sometimes glaring differences in these documents.

During balloting of the 2000 IBC, a proposal was made (S89-99) to "fix" part
of the redundancy section by adding the sentence "For design of diaphragms
and collectors, a rho of 1.0 may be used."  The proposal was disapproved by
the committee (including influential members of SEAOC); the committee's
response was "The reliability factor should apply to the design of
diaphragms and collectors."  Apparently there is not consensus on this
matter (even within  SEAOC).

Although I believe that the idea of requiring redundancy is sound, I must
agree with Charles Greenlaw that the present codification of redundancy is
"a regular Rosemary's Baby."

> -----Original Message-----
> From: Mark Swingle [mailto:mswingle(--nospam--at)]
> Sent: Sunday, January 14, 1996 7:20 AM
> To: seaint
> Subject: Rho for diaphragms
> The Seismic Design Manual states in at least three places that rho
> does not apply to diaphragms.  Unfortunately no code reference is
> given for any of these three notations.
> Can anyone cite the CODE reference (97 UBC) where this is stated?
> thanks in advance
> Mark Swingle, SE