Beam-to-Beam Connection (Simple question) 1

[gharli]

Hi All,

In this very short 30 second video from steelconstruction.info (UK based organisation). Two Beam-to-beam connections are shown. The second detail has the incoming beam connecting directly to the flanges of the supporting beam. My questions are:

1. Will this connection induce torsion into the supporting beam considering forces don't go straight into the web?
2. If the flexible "bracket" as they call it in the video has a perpendicular stiffener that is also welded to the supporting beam's web will the torsion increase or decrease in the supporting beam.

Link to the video: Link

Would appreciate your thoughts.

Thanks!

 

[human909]

1. Yes.
2. If you stiffen the connection like you say then you are getting close to creating a moment connection. Then the torsion becomes dependent on the curvature of the incoming beam. So it could increase or decrease the applied torsion depending on the beams stiffness and load.


It is not a connection I like. I don't see too many obvious benefits of this type of connection. It is neither cost nor structurally efficient.

 

[MIStructE_IRE]

Yes it will induce torsion. Fabricators like it because it’s easy to erect. I never permit this type of connection though as I don’t like the torsional effect.

 

[BAretired]

Well, if the bolts are able to resist a moment of R*e where R is the beam reaction and e is the eccentricity, the rotation of the supporting beam is held to the end rotation of the supported beam. Torsion in that situation does not need to be considered. In fact, the same is true if the supported beam is end plate connected to the web. So, in essence, the answer to the first question is NO!

I like the idea of a stiffener connected to the web because otherwise, you are relying on the top and bottom flange of the supporting beam to resist the reaction in bending.

BA