Unique Connection Help
Unique Connection Help
(OP)
I need some help choosing the best way to make a connection.
The situation: 3x3x1/4 square tube being connected to the underside of a W27x84. It must be a rigid moment connection (used to support a sign being canilevered out)
Considerations: I know the conroversy about leaving it to the detailer or having the EOR design the connection...but my preference is to design what I can. Plus, I think that only applies to simple connections...not moment connections.
Obviously, I am thinking weld here and probably on four sides with the vertical welds taking the vertical/horizontal load and the top and bottom welds resisting the moment. Am I on the right track? When welding tubes, are there provisions I need to account for which need to be included on the contract drawings?
Thanks!
Picture attached illustration the situation...initial weld locations shown in magenta.
The situation: 3x3x1/4 square tube being connected to the underside of a W27x84. It must be a rigid moment connection (used to support a sign being canilevered out)
Considerations: I know the conroversy about leaving it to the detailer or having the EOR design the connection...but my preference is to design what I can. Plus, I think that only applies to simple connections...not moment connections.
Obviously, I am thinking weld here and probably on four sides with the vertical welds taking the vertical/horizontal load and the top and bottom welds resisting the moment. Am I on the right track? When welding tubes, are there provisions I need to account for which need to be included on the contract drawings?
Thanks!
Picture attached illustration the situation...initial weld locations shown in magenta.





RE: Unique Connection Help
I have attached an alternate, with a little less field welding and bolts for erection and the shear load.
http://www.FerrellEngineering.com
RE: Unique Connection Help
RE: Unique Connection Help
RE: Unique Connection Help
RE: Unique Connection Help
RE: Unique Connection Help
Adding the stiffener below the HSS, shortens the cantilever length, thus reinforcing the HSS. But, similar bending still occurs in the beam flange and web. If necessary a combination of both can be used, stiffener below HSS and backup stiffener in beam.
Depending on the number of HSS connections along the length of the W27, the W27 should be adequate for the torsion. Note, that the end connections for the W27 should probably be full depth.
http://www.FerrellEngineering.com
RE: Unique Connection Help
All of the details suggested appear to address the connection of the HSS to the beam flange, but I would suggest that there are two possible sources of torsion that merit consideration.
1st, the entire W27 might be able to rotate between its ends, you should review the span and determine if any connecting members restrain rotation.
2nd, local warping of the flange, the web below the fillet could behave similar to a fulcrum and the top flange could "tip". This affect would be greatest at the HSS and warping of the flange would diminish in relation to distance from the HSS.
Personal experience has been a stern teacher with regard to torsion on open sections (wide flange, channels, etc.). An owner does not care if the section has adequate strength if it does not provide adequate serviceability.