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RE: new SEAOC seismology web page

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"Almost right" meaning that it is INTENTIONAL that we poor structural
engineers are faced with doing the redundant calculations for R=4 for no
apparent benefit to life safety?

Shouldn't this be corrected?

What's wrong with this picture?

Bill Allen, S.E.
ALLEN DESIGNS
Laguna Niguel, CA


=>-----Original Message-----
=>From: Mark E. Deardorff [mailto:MarkD(--nospam--at)DandDEng.com]
=>Sent: Wednesday, December 22, 1999 4:14 PM
=>To: seaint(--nospam--at)seaint.org
=>Subject: RE: new SEAOC seismology web page
=>
=>
=>That is almost right. When SEA first incorporated the NEHRP
=>provisions the changed the R values for working loads by
=>dividing by 1.4 and rounding to achieve the Rw values. When
=>they went back to Ultimate loads they forgot to go back to
=>the NEHRP values and just multiplied by 1.4 yielding slightly
=>different values.
=>
=>> -----Original Message-----
=>> From: Bill Allen [mailto:Bill(--nospam--at)AllenDesigns.com]
=>> Sent: Wednesday, December 22, 1999 4:00 PM
=>> To: seaint(--nospam--at)seaint.org
=>> Subject: RE: new SEAOC seismology web page
=>>
=>>
=>> Me first! Me first!
=>>
=>> Ref: 1997 UBC Code, section 1633.2.9.3 (R not exceeding 4).
=>>
=>> In the old code, 1994 UBC, section 1631.2.9.3, the limitation
=>> was Rw<=6.
=>> When designing wood framed structures under the old code
=>> using a Rw=6 (Table
=>> 16-N, item 1.1.b), this requirement was invisible. Now, the
=>> designer is
=>> required to produce MORE (IMO tedious and worthless)
=>> structural calculations
=>> for the same structure since R=4.5 for item 1.1.b in Table 16-N.
=>>
=>> My Question:
=>>
=>> It appears to me that Table 16-N and section 1633.2.9.3 were
=>> given to two
=>> engineers to translate to the 1997 UBC code language (i.e.,
=>> divide by 1.4)
=>> with one engineer rounding up to 4.5 in Table 16-N and one
=>> engineer rounding
=>> down to 4 in section 1633.2.9.3 and the seismology
=>committee failed to
=>> coordinate the two. Is this the case or has the seismology committee
=>> discovered some scientific data or anecdotal evidence which,
=>> in the interest
=>> of life safety, warrants the additional structural
=>> calculations? Or, should
=>> UBC section 1633.2.9.3 be amended to read "...R not exceeding 4.5."?
=>>
=>> Regards,
=>>
=>> Bill Allen, S.E.
=>> ALLEN DESIGNS
=>> Laguna Niguel, CA
=>>
=>
=>
=>