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Re: ACI 318 Appendix C

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     Regarding ACI 318 Appendix C Load combinations
     
     The E in ASCE 7-88 is based on the 1985 UBC's "allowable stress based" 
     definition of earthquake forces.
     
     The E in ASCE 7-95 is based on the 1994 NEHRP Provisions' "strength 
     based" definition of earthquake forces.
     
     1.5 is the old conversion factor between allowable stress and strength 
     based earthquake forces.  The 1997 UBC uses 1.4.  The Final Draft of 
     the 2000 IBC uses 1.4
     
     Rick Drake, SE
     Fluor Daniel, Irvine
     
     ***************************************************************
     
Reed R. Figley wrote:

I am designing a building using both concrete and steel elements using ACI 
318-95 strength design and LRFD 2nd ed., respectively.  I would like to use 
a uniform set of load cases for both, which is provided for by Appendix C 
of the former.  The problem is that LRFD has gone to the ASCE 7-95 load 
combinations, where earthquake (E) is multiplied by 1.0.  This disagrees 
with ACI Appendix C, which references the ASCE 7-88 load combinations, 
where E is multiplied by 1.5.  Does anybody know how this is currently 
being handled?  Has ACI issued an addendum addressing this?
     
Further, does anybody know of a reason why this approach would be 
undesirable?
     
Reed Figley, P.E. 
Boise, Idaho
reed_figley(--nospam--at)mk.com