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Re: UBC 1997 Seismic Provisions for Steel Buildings

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Ed:

My comments are inserted below.

-Mike

> Date:          Tue, 10 Aug 1999 09:32:09 -0700
> From:          Eddie Gonzalez <Eagonzal(--nospam--at)ENG.CI.LA.CA.US>
> To:            seaint(--nospam--at)seaint.org

> At a recent seminar, the following items were brought up or led to my personnal
> discovery which may worthy of discussion on this list:
> 
> Item 1: Omega Factor (Seismic Force Amplification Factor) is also included for
> calculations of equations in Division V, Sect. 2213.5.1
> 
> Item 2: The term "gravity loads" in Sections 2213.6.2 and 2213.7.2.1 was
> interpreted to mean "factored DL & LL".  I personnally disagree since 1) this
> already existed in the 1994 UBC where the loads were calculated using working
> stress. 2) When this section (chp22) want one to use load combinations, it
> usually states it emphatically (ie. 2213.5.1).

The interpretation "factored DL & LL" is incorrect.  Section 2212 
clearly states that Division V uses the "load combinations of Section 
1612.3."

> 
> Items 3: There are two guidelines for the design of ASD.  One is at the end of
> Part II of Div. 4 and the other is all of Div. 5. of Chap 22 of the Code. 
> Which one are people using?

This looks like a mistake on the part of the code writers.  When they 
inserted the AISC Seismic Provisions they should not have taken along 
section 2211.5 since it has the same applicability as Division V.  If 
I used ASD, I would use Division V as it is probably one step closer 
to the real intent (not using fudge factors to modify other fudge 
factors).

> 
> Regards,
> ed gonzalez

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Michael Valley                                   E-mail: mtv(--nospam--at)skilling.com
Skilling Ward Magnusson Barkshire Inc.                  Tel:(206)292-1200
1301 Fifth Ave, #3200,  Seattle  WA 98101-2699          Fax:        -1201