Beam to Beam moment connection 1

[twinnell]

You have two beams framing into a girder, one on each side. The two beams are in line. One beam is a cantilever fastened with a moment connection to the girder. Can the other beam be a simple shear connection or does it have to be a moment connection? I have seen it designed both ways. It has been said that since the other beam frames into the girder opposite the moment connection, that beam will stiffen the girder enough to resist the torsion created by the cantilever. Can anyone tell me if this is true or what is industry standard. Where can I find literature on this?

Most of the time we put a moment connection on both sides of the girder.

 

[valleyboy]

I think it depends on how you deal with the moment at the end of the cantilever.

If the main girder is designed to resist the vertical reaction plus the torsion from the cantilever, then the other connection may be 'pinned'.

If however the main girder is designed to carry the vertical reaction only, and you are relying on the second beam member to resist the moment from the cantilever, then both connections will need to be moment connections.

 

[swivel63]

depends on your connection. if you put that moment connection, then it will be a cantilever with the backspan on it. personally, i would put the moment connection and call it a day.

 

[swivel63]

oh yea, i think you're deflection will be higher if you don't make it a moment connection because that beam will rotate if it has nothing to pull it back. someone correct me if i'm wrong.

 

[JAE]

Both connections MUST be moment connections if your girder is a wide flange. Wide flanges have almost zero torsional stiffness so having the cantilever beam fixed to the girder, with the opposing beam pinned, will depend on torsional stiffness you don't have.