Larry Hauer wrote:
> Thanks Tom, that is what I thought with WOOD and masonry the only
> materials being allowed the 1/3 increase. (Oh well!).
>
> Larry
>
> ------------------------------------------------------------------------
> To: seaint@seaint.org
> Subject: Re: Steel strsss increase for seismic loads
> From: Tom.Hunt@fluor.com
> Date: Tue, 21 Apr 2009 14:22:48 -0700
>
>
> Larry,
>
> If you use the load combinations from IBC Section 1605.3.1 then a 1/3
> increase in allowable stresses is not permitted. If you use the IBC
> load combinations from Section 1605.3.2 then you are allowed to use
> the 1/3 increases *but ONLY if allowed by the material chapter*.
> Unfortunately for steel neither the IBC nor AISC have the 1/3
> increase factor anymore. I believe the only material left is masonry
> and in some cases geotechnical soil bearing.
>
> Thomas Hunt, S.E.
> Fluor
>
>
>
>
>
> *Larry Hauer <lhauer@live.com>*
> 04/21/2009 02:09 PM
> Please respond to seaint
> To
> "Struct. Eng. Assoc." <seaint@seaint.org>
> cc
>
> Subject
> Steel strsss increase for seismic loads
>
>
>
>
>
>
>
>
>
> I am checking existing steel roof framing members for support of
> replaced roof top mechanical equipment. Obviously, I need to design
> per the '06 IBC/'07 CBC for seismic forces and will be using ASD
> equation 16-20 of the IBC/CBC. Based on Sec. 1605.3.1.1 it looks like
> a 1/3 increase in allowable stresses for the existing steel roof
> members is no longer allowed when considering seismic loads. Is this
> correct?
>
> Thanks in advance,
>
> Larry Hauer
>
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