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RE: Steel beam unbraced length limit

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Matthew. 
I try to avoid those cap channels where I can,
because they create problems: fit up, flatness,
sweep or camber, access for welding, stitch weld
versus continuous, etc.  The biggest problem I run
across is that engineers just check to see if the
cap channel fits on the wide flange, but they never
ensure it is wide enough for the welder to get a decent
45 degree fillet.  Just went through this with a
customer who put a C12 on a W24.  The thickness of flg
material dictated a 5/16" fillet per the welding code
but in a single pass at that angle of approach gave him
something like 3/16" on the vert leg.  I made him add a
second pass to build up the weld to 5/16" and he was
none too happy with me.  As if I chose the d**n channel.
Gary
happy

On 26 Feb 2005 at 9:57, Stuart, Matthew wrote:

> 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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