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Re: Bracing the compression flange on steel beam?

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> From: Andy Costello <acost(--nospam--at)cwfab.com>

> How about a technical question, for a change.
> Is a lateral brace that is attached from the tension flange 
> to half way up the web considered an effective brace?

Is this a brace connected to a stiffener plate/clip that is half the
depth of the member?

> Some would say that the stiffness of the web can support its comp flange,
> and keep the beam section from twisting, hence Lc reduced.
> I have some references but still not clear, your option is appreciated.

Things to consider:
1) h/w and h(clear)/w; clear is above stiffener
2) what is the stress level in the flange
   (% with and % without brace considered)
3) will the web, connection and stiffener combined be STIFF enough to
   actually function per assumptions as a comp flange stiffener?
4) is there a conc/udl load nearby
5) is this fab'd/erected or in design?

If the item is still in design, rework for your personal knowledge and
comfort level. If not, the analysis could get ugly and expensive
compared to simply improving the brace. Ignoring it may become even
uglier and more expensive.

If h/w is high, then fix the brace or ignore its existence as a comp
flange brace. If the brace/stiffener combination is a RIGID moment
restraint for the web and h(clear)/w is low, you may be lucky.

Chances are, especially if Mu/Mr approaches 1, that you are wasting your
time doing the analysis - the flange will need a direct, stiff brace.

-- 
Paul Ransom, P. Eng.
Civil/Structural/Project
Burlington, Ontario, Canada
<mailto:ad026(--nospam--at)hwcn.org> <http://www.hwcn.org/~ad026/civil.html>