Torsion capcaity of a Fin or shear tab steel connection with top flange connected

[allimuthug]

Hi
I have a shear tab connection of HE400 A (European Section) longitudinal beam with HE300 A column as shown below.

The cross looks like this

When some pipe supports are supported on the longitudinal beam, as shown the picture above shall cause torsion on the beam.
The beam is restrained by the bolts on the web and top flange. Please explain me how to find the torsional capacity on the beam.

 

[WARose]

Please explain me how to find the torsional capacity on the beam.

In my opinion, you'd have virtually none because the bottom flange of the beam is not restrained. Ergo the torque will get to the "stiffener" by bending in the web (which likely doesn't have much capacity). If you restrained the bottom flange as well.....you might be in business.

 

[allimuthug]

It means the T beam doesn't have any torsional capacity. I can understand that the couple is formed from the web and the flange.
What does the top flange do in this case?

 

[WARose]

A T-beam does have torsional capacity......but you've got this thing welded (if I understand this pic correctly) to the bottom flange of a I-Beam.

In the case of no restraint of either flange.....we've discussed this before (on the board):

http://www.eng-tips.com/viewthread.cfm?qid=427598

Note my diagram in the thread. You'd have half of that situation here.....but it would still be enough to put the web (above the bottom flange) in bending. (Which would likely fail it for any significant load.)