VERSION:2.1
N:Andrew Kester;PE
FN:Andrew Kester, PE
EMAIL;PREF;INTERNET:akester@cfl.rr.com
REV:20090114T151958Z
END:VCARD
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.
Orlando, Florida
Orlando, Florida