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RE: UBC Eq. 30-1

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Gerard,

ACI 318-02 now uses the same load factors as ASCE 7.  The resistance
factors (phi) have been adjusted to work with those factor.  You should
also note that the old Appendix B was moved into the main body of the code
while the "companion" stuff that was in the code is now in Appendix B.
This effects phi for flexural and compression members.

Thus, the 1.1 adjustment in the UBC would no longer be necessary if there
were future versions of the UBC.  But since there will be no future
versions of the UBC, you will want to look at the IBC.  The IBC has a
similar provision, but rather than multiply the IBC load combinations by
1.1, the IBC has you use the ACI 318 load combinations for combinations
without seismic and adjust the wind loads portion and just use the IBC
combinations when dealing with seismic.  This provision should go away in
the 2003 IBC.

BTW, there has been alternate load factors for use with ACI 318-99 (and
before) in Appendix C that correspond to the ASCE load factors.
Basically, the 2002 ACI 318 moved Appendix C into the main body of the
code and moved the old load factors into Appendix C.

For masonry, the new Strength Design provisions in the 2002 MSJC (ACI 530)
references ASCE 7-98 for load combinations IF the governing code does not
provide load combinations.

HTH,

Scott
Ypsilanti, MI


On Thu, 12 Sep 2002, Gerard Madden, PE wrote:

> Thanks Rick & Scott,
>
> This makes sense now that I think about it... I have never understood
> why ASD was immune from this in UBC, probably just to punish an LRFD man
> like myself.
>
> What's the update on the 1.1 factor for concrete in the load combos? I
> heard they were going to be the same now, but some are still against
> this. I don't think ASCE has a this multiplier.
>
> -gerard
> Santa Clara, CA
>
> -----Original Message-----
> From: Rick.Drake(--nospam--at)Fluor.com [mailto:Rick.Drake(--nospam--at)Fluor.com]
> Sent: Thursday, September 12, 2002 8:50 AM
> To: seaint(--nospam--at)seaint.org
> Subject: RE: UBC Eq. 30-1
>
>
> E-sub-v is defined in the 1997 UBC as "an ADDITION ... to the dead load
> effect."  SEAOC, as explained in the 1999 Blue Book, intended that
> E-sub-v
> be applied in both vertical directions.  In other words, add E-sub-v for
> most load combinations and subtract E-sub-v for "uplift" load
> combinations.
>
> The 2000 IBC makes this clear.  The 2000 IBC also applies it to both
> working stress design and strength design.  ASCE 7-02 will also apply
> the
> vertical earthquake in both vertical directions for both working stress
> and
> strength design.  ASCE 7-02 will be adopted by reference by the next
> generation of IBC and NFPA Building Codes.
>
> Regards,
>
> Rick Drake, SE
> Fluor Daniel, Aliso Viejo, CA
>
> *********
>
>
>
>
>
>                     "Gerard Madden,
>
>                     PE"                  To:     <seaint(--nospam--at)seaint.org>
>
>                     <gmadden@attbi.
>
>                     com>                 cc:
>
>                     09/11/02 01:40
>
>                     PM                   Subject:     RE: UBC Eq. 30-1
>
>                     Please respond
>
>                     to seaint
> .....
>
>
>
>
>
>
>
>
> Ev is only used in non-working stress design. It is a reduction factor
> for dead lead and acts Upward. SO combine this term with your DL and
> you'll get something smaller than 0.9D in your load combo.
>
> -gerard
> Santa Clara, CA
>
> -----Original Message-----
> From: RainCat1(--nospam--at)aol.com [mailto:RainCat1(--nospam--at)aol.com]
> Sent: Wednesday, September 11, 2002 1:18 PM
> To: seaint(--nospam--at)seaint.org
> Subject: UBC Eq. 30-1
>
> In the UBC Eq. 30-1 E=rhoEh + Ev, what is the direction for Ev?
> Are we suppose to combine numerically the expressions rhoEh & Ev?
> Thanks!
>
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