HSS one sided moment connection

[sadienerd]

I am designing a 30,000sq.ft mezzanine in a low seismic area (SDC B). I am wanting to know what the most economical and generally used one sided moment connection between a wide flange beam and tube column is. I will have about 16 bents in total with the interior connection being continuity plates at the top and bottom of a beam that bears on top of the HSS column tube column with cap plate). Two of my moment connections are at the end of the mezzanine and will require one sided connections. I am wanting to avoid the directly welded connection as I don't want to trigger the contious special inspection requirements from the pjp welds( has anyone had success from this type of connection. Using fillet welds?) My lead designer is questioning using a cut out bolted diaphragm plate connection because he believes it will need to be a slip critical connection(connection is for the LSFR system). With those two out I am struggling to find an adequate detail for this connection. The connection will need around 65k-ft of capacity.

As a side note, I have noticed that my analysis is showing the moment at the coulmm connections to be lower than at the mid span of the beam. Reviewing the calcs the low stiffness of the columns appears to be shedding load back to the moment frames beam. This feels right to me but I am curious if this throws up any red flags that this connection will behave more like a flexible moment connection.

 

[jdgengineer]

Check out CIDECT Design Guide #9 it's a great resource for HSS connections.

A sketch would probably help explain your exact condition. If the fillet welds calc out I don't have a philosophical reason against them. You may be able to find a bolted option possibly with blind bolts if for non-seismic and loading is small.

 

[calvinandhobbes10]

Based on your description of interior columns I am guessing the HSS columns stop at the mezzanine level.

If that's the case I would run the wide flange over the end HSS and use four pretnsioned bolts from column cap plate to the bottom flange. Add stiffeners in beam web as needed.

If that doesn't meet your constraints you should just deal with the continuous inspection of a 3/8 fillet weld or whatever a top and bottom plate would need. That's the detail I usually use.

Last, and more generally---it sounds like yo are doing a freestanding mezzanine, with moment frames stabilizing for seismic. Does the mezz connect to the roof supports? Can that help reduce your load? Do you have no room for knee braces between the beam and HSS? I found those most efficient when can't get braced frames.