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Re: Ev in UBC Equation 12-5/12-6

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The 1999 Blue Book is different than the previous six editions, which preceded
the referenced UBC.  The 1999 edition is sandwiched in between the 1997 UBC and
the 2000 IBC.  Provisions and commentary in the 1999 Blue Book do not always
agree with the 1997 UBC.  Sometimes it supports proposals to the 2000 IBC.
Places of Blue Book disagreement with the 1997 UBC are indicated by a vertical
line in the margin.  The part of the Blue Book regarding E-sub-v is one of these

One argument for not applying E-sub-v to 1997 UBC "uplift" equation 16-5 is that
the minus 1.0E term is overly conservative to "columns" with tension components
due to lateral loads.  However persuasive this argument may be, the 1997 UBC
requires that  E-sub-v (part of E as defined in Section 1632) must be considered
in BOTH strength design equations 12-5 and 12-6.  Per Section 1632, E-sub-v need
not be considered in allowable stress equations 12-9, 12-10, 12-11, 12-13,
12-16, or 12-16-1.

Rick Drake, SE
Fluor Daniel, Aliso Viejo


"Julian Chu" <julian(--nospam--at)> on 03/27/2000 01:10:42 PM

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

To:   <seaint(--nospam--at)>

Subject:  Ev in UBC Equation 12-5/12-6

The 1999 SEAOC Bluebook page 9 states  that Ev applys to the UBC load
combination 12-5 but not 12-6. The  commentary explains the reason for adding
the Ev to 12-5. However, there is no  information given regarding the 12-6. I
know a lot of us have been subtracting  the Ev = 0.5CaID from the 0.9D in the
12-6 which may give you a more  conservative result for uplift or tension force
than the past strength design  provisions.

Does anyone know the reason why Ev need not be  included in the 12-6?


Julian Chu
Newport Beach, CA