Andrew and MJ:
Thank you for your response. I did not want to go through the AISC formula and was hoping to find a quick and dirty rule of thumb if there were any.
I solved the problem by refiguring the framing members to take the torsion.
Gautam
From: Andrew Kester, PE [mailto:akester@cfl.rr.com]
Sent: Wednesday, January 14, 2009 7:20 AM
To:
Subject: re: curved channel
Gautam,
This is covered in AISC if you have the manual, it works like biaxial bending, there is an interaction equation involved. It has been a while since I have hand calc'd it, not that hard but the iterations can be time consuming.
There may be other issues with a channel, as it seems like the worse shape besides an angle to put into torsion. Too bad the architect eliminated the best shape for this situation- HSS. It just seems like the outer legs of the channel would have buckling issues, something that would need to be checked. No way to use outriggers or other framing members to eliminate or decrease the torsion via force transfer??
Good luck, sorry I don't have the formulas handy...
Andrew Kester, P.E.