Steel beam to beam moment connection

[Gopher13]

I have a somewhat typical steel beam to steel beam moment connection (see attached). The cantilevered end of the moment connected beam is 16 feet. Strength does not control as I am only at about 40% capacity. However, I very much care about limiting deflection of the cantilevered end. My question is: Do I design the moment connection for the full bending capacity of the beam or do I design it for the actual moment on the beam? Surely, a moment connection with 2 rows of 3 bolts will rotate more than one with 2 rows of 12 bolts as I have shown, right? AISC 13th ed. Commentary on Specification Section B3.6 (pg. 16.1-218) appears to maybe address this but I am struggling to understand it.

 

[dik]

I'd design it for the moment on the beam... realising that cantilevers do not offer much re-distribution of load.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[ProgrammingPE]

I agree with dik and would likely design for the actual moment using conservative numbers. Your decision should ultimately be based on strength considerations rather than deflection considerations.

Since you are using slip critical bolts, the stress is being transferred through friction between the plate and the flange, not through shear in the bolts. This means that as long as the amount of friction is sufficient to prevent the bolts from slipping, adding additional bolts will not increase the stiffness of the connection, since the stress does not pass through them. If you are concerned about deflections, increasing the size of the flange plates or the wide flange beams will have a more significant impact than adding additional bolts.

You'll also need to make sure that the initial camber gets set correctly, and that the effect of vibrations are considered.

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[Gopher13]

I appreciate the responses. Explanation on slip critical bolts not moving makes sense. I will design for the actual moment. Thanks again!!!