Torsion Restraint on Steel Beam

[sgs114]

Hello,

I have a unique condition that I am not sure how to address some torsion that I am putting on an (E) WF Beam. The beam is spanning across an opening and we want to put a track on top of for some equipment. The equipment load does not align with the centerline of the beam, so there is some torsion on the beam. At the area there is no metal deck on the top flange, but there is a angle brace diaphragm to brace the beams. My question is: am I going to run into difficulty bracing the beam for torsion since I don't have a diaphragm to brace it to? I was going to brace the bot flange of the beam, but doesn't really seem like I have anything to brace it to. Now thinking of using full depth stiffener plates to connect the bracing beams, but again I don't have a diaphragm on the top flange, so not sure that addresses my loading. Thoughts/input?

Link to plan:

https://files.engineering.com/getfi...542-4e9e-9b89-eea255dba673&file=Document1.pdf

 

[hotmailbox]

Add stiffener plate at the load point and angle like this. Two beams work like a horizontal truss as-is so diaphragm may not be needed.

 

[WARose]

My question is: am I going to run into difficulty bracing the beam for torsion since I don't have a diaphragm to brace it to? I was going to brace the bot flange of the beam, but doesn't really seem like I have anything to brace it to. Now thinking of using full depth stiffener plates to connect the bracing beams, but again I don't have a diaphragm on the top flange, so not sure that addresses my loading. Thoughts/input?

What you show in your "Section A-A" is what I have used myself to handle torsion in girders. (Especially in the case of light loads.) A couple of important differences though: #1-I'd make the girders the same depth. #2- I'd make it a 3 bolt connection on those intermediate members that run between the girders. #3- Be sure the ends of those girders will not try to transfer (significant) torque to those columns via a simple shear connection. (The web of most beams can't take it. You may have to have one intermediate member close to a support (which will look odd to everybody....but that's how it goes).

More comments: make sure you account for this in your model. The torque will run into those intermediate members as strong-axis moment. You'd release about 90% of the strong-axis fixity on the (ends of) intermediate members.....since we are talking simple shear connections making the transfer. The connection to the girder is how it needs to be. (I.e. plate welded to flange and web of girder. Show that on your section detail so the fabricator knows that is what you want.)

Anyway.....if you account for this......it can easily be done.