RE: Coped beams[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
- Subject: RE: Coped beams
- From: Charlie Carter <carter(--nospam--at)aiscmail.com>
- Date: Mon, 5 Mar 2001 07:54:54 -0600
> Beam is W24x55, L=18'-3, A992 Copes are:
> top: 3 x 6 7/8 deep bottom: 3 x 4 3/4 deep
> What has to be checked and what kind of reinforcement
> has to be applied for yielding and what for buckling?
That's a pretty significant reduction in the beam. Any chance of changing the size of the supporting member (I assume it is a girder) to a deeper member? The added weight at 20 cents per pound will easily be offset by savings in labor by eliminating or minimizing coping and reinforcement (if reinforcement is necessary).
If you have to live with coping, three additional limit states may apply: lateral-torsional buckling, local buckling and yielding.
Lateral-torsional buckling, in my experience, only becomes a problem when there is a very long cope. There is some guidance for these cases in the Guide to Stabilioty Design Criteria for Metal Structures. Essentially, the beam is modelled as three segments with the corresponding cross-sectional properties. I'd be very surprised if 3-in.-long copes made any difference, though.
For local buckling, there is the Manual procedure that addresses top or top and bottom coping within the limits stated. Beyond those limits, right now, you're on your own. But the 3rd Edition LRFD Manual, which we are creating right now, will have a procedure to address copes that exceed the current limitations. I'd be happy to share it with you now if you email me your fax number privately. Note, I'm on my way out of the office for the bulk of this week, so I'll have to fax it to you when I return.
For local yielding, the Manual procedure is not subject to the limitations of the local buckling limit state.
As far as reinforcement goes, when necessary, longitudinal stiffeners fillet welded to the web or a web doubler plate fillet welded to the web are two potential solutions.
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