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RE: 1997 UBC 1630.1.1

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When we design walls, columns, etc., we combine vertical (DL, LL) forces
with horizontal (E) forces all the time.  In Sect. 1630.1.1 it says that
the horizontal forces used should equal rho times E, and the vertical
forces, in addition to the factored vertical DL and LL components, should
include a vertical E force.

Note that a paper by S.K. Ghosh was published in the ICBO Standards
magazine about 6 to 9 months ago that made the position, with the backing
of SEAOC Seismology, that the vertical E component should be used with load
combination Eqn 12-5, and not with Eqn 12-6.  The essence of the vertical
component is that the net vertical load using the new 1.2D + 1.0 E
combination will be about the same (in zone 4) as the old 1.4D combination
in the 94 UBC.








Al Grathwol <AGrathwol(--nospam--at)BoyleEngineering.com> on 07/13/99 02:26:55 PM

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


                                                              
                                                              
                                                              
 To:      "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>           
                                                              
 cc:      (bcc: Martin W. Johnson/EQE)                        
                                                              
                                                              
                                                              
 Subject: RE: 1997 UBC 1630.1.1                               
                                                              








Thank you- but what about horizontal loads combined with vertical loads,
like in section 1630.1.1?

> -----Original Message-----
> From: Martin W. Johnson [mailto:MWJ(--nospam--at)eqe.com]
> Sent: Tuesday, July 13, 1999 2:29 PM
> To: seaint(--nospam--at)seaint.org
> Subject: Re: 1997 UBC 1630.1.1
>
>
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> vertical loads are applied in the vertical direction, and
> horizontal loads
> are applied in the horizontal direction.
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> Al Grathwol <AGrathwol(--nospam--at)BoyleEngineering.com> on 07/13/99 02:01:57 PM
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> Please respond to seaint(--nospam--at)seaint.org
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>  To:      "'SEAOC List'" <seaint(--nospam--at)seaint.org>
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>  cc:      (bcc: Martin W. Johnson/EQE)
>
>
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>  Subject: 1997 UBC 1630.1.1
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> Equation 30-1 combines the effects of horizontal and vertical
> earthquake
> loads.  However, the code fails to indicate how the combined
> load is to be
> applied for purposes of design.  Are we to infer that this
> combined force
> is
> supposed to be applied in the horizontal direction only?
> It's not clearly stated in the code.
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