Drag beam connection

[bouk715]

When detailing a connection between a steel drag beam and an adjacent braced bay, what type of connection is preferred? I suppose a typical double angle connection could be used, but the prying action on the tension side could become a problem. The columns are tubes...could a rectangular shear tab connect between the two beams through a slot in the tube? If the beams are each bolted to the shear tab, I wouldn't think this would affect my beam end fixity.

 

[14159]

It's difficult to intelligently reply without seeing structural drawings.

"When detailing a connection between a steel drag beam and an adjacent braced bay, what type of connection is preferred? I suppose a typical double angle connection could be used, but the prying action on the tension side could become a problem."

I've seen double angles for this before, if the beam is connected to a WF column. You would have to design bolts for the combined shear and tension including prying forces. The AISC procedure (see Fig 9-4 of the 3rd Ed. Manual) should be used.

"The columns are tubes...could a rectangular shear tab connect between the two beams through a slot in the tube?"

I don't know a reason why this wouldn't work, although can't be sure without seeing your drawings. Back on the previous question: If you have HSS, how could we have the prying action issue mentioned earlier?

"If the beams are each bolted to the shear tab, I wouldn't think this would affect my beam end fixity."

You need to follow the AISC 3rd Edition rules for shear tab eccentricity for a fixed support. Beam end rotational restraint is usually ignored even for shear tabs if these provisions are satisfied.

You might consult the 1997 AISC HSS Manual also. They have lots of info for connections to HSS columns.

I think it mainly has to do with the magnitude of your forces and size of your columns. If your columns are small (even HSS4x4 or 6x6) then your double-angle idea is probably out, leaving you with some kind of shear tab like you suggest. Without knowing more about your situation, my best guess is that your knife-plate shear tab is probably best.

Another thought: Can you stack the columns in this area? That might allow you to run the braced frame beam through and shear splice it to your drag strut.

DBD