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RE: Steel beam unbraced length limit

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Probably because you placed a channel on top of the beam to help brace the compression flange.

________________________________

From: Gary Hodgson & Associates [mailto:ghodgson(--nospam--at)vaxxine.com]
Sent: Sat 2/26/2005 9:03 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: Steel beam unbraced length limit



I wonder how I ever designed all those crane runway
beams of 40-50 ft length
Gary


On 25 Feb 2005 at 9:12, Sherman, William wrote:

> In general, I would not place a limit on unbraced length as long as
> the beam meets the code requirements. However, I sometimes get nervous
> when the allowable stress based on the code is very low - although
> this forces the applied loads to also be very low, it implies that the
> beam does not have much lateral stiffness.
>
> William C. Sherman, PE
> (Bill Sherman)
> CDM, Denver, CO
> Phone: 303-298-1311
> Fax: 303-293-8236
> email: shermanwc(--nospam--at)cdm.com
>
>
> > -----Original Message-----
> > From: Will Haynes [mailto:gtg740p(--nospam--at)hotmail.com]
> > Sent: Thursday, February 24, 2005 1:50 PM
> > To: seaint(--nospam--at)seaint.org
> > Subject: Steel beam unbraced length limit
> >
> > I have designed steel beams with unbraced lengths up to 20 ft
> > before (above "Lr" value).  I have had other engineers tell
> > me they won't design for an unbraced length this high even if
> > it works by AISC equations, I guess due to their fear of
> > fabrication and erection influences on the beam and this
> > being magnified by a larger unbraced length.  Isn't this
> > already accounted for in the AISC equations?  Any thoughts?
> >
> > Will Haynes
>
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