Ordinary Moment Frame Connection Upgrade

[Croceng78]

I am analyzing an existing ordinary moment frame connection (end plate at beam to column interface) and determined that the plate fails in bending. Is adding a web stiffener at the middle of the plate a viable solution to help reduce the plate bending? If so, how would I analyze the plate with the new web stiffener? Would I need to do some finite element analysis? Thanks in advance for your time.

 

[SWComposites]

A sketch of where it is failing in bending would help.
Why not just make the plate thicker?

 

[Croceng78]

To make the plate thicker, do you mean by welding new plates to the existing plates? You would probably only be able to weld a small plate to it but not the entire length of the connection...

 

[human909]

Generally it makes little sense economically to start throwing in more plates to stiffen things when you can just increase the thickness of the end plate. In general when it comes to moment connections DO NOT be frugal on the thickness of the connecting plate.

One exception that springs to mind because I addressed it TODAY is if you end plate is intersecting the column in its minor axis. Then web stiffeners on the opposite side make sense and are often necessary as webs are thin.

 

[Flotsam7018]

Yes, adding stiffeners in the correct locations will result in additional yield lines in the end plate. Have a look at AISC Design Guide 39, the basis of which is yield line analysis but they provide simplified equations, one of which likely fits your scenario.