Bolted connections and releasing moments

[JRS56]

I'm working on a petrochemical equipment structure that is galvanized and most connections are bolted double clip angles. This allows everything to be assembled after galvanize without welding. My question is about how to define the end connections. Usually I set the values as "Partial Moment Release MPY = .99 & MPZ = .99" and allow the bracing to pick up most of the lateral forces. On this project because of the equipment configuration, bracing is becoming complex/expensive, specifically the floor diaphragm braces. As an added constraint, the fabricator is requesting all the clip angles be bolted to both beams. Usually we weld the clips to one beam and bolt to the other.

I'm curious how you guys handle bolted connections and the ability to transmit moments?

In this case, with double bolted double clip angles, it seems like MPZ would be different than if the clips were welded on one end and bolted on the other?

Thx in advance.

 

[SethGuthrie]

I think the common practice is to assume a pinned (hinged) connection at a bolted double angle connection, in both axes. If you want to have partial fixity that is something that STAAD.Pro analysis can handle, but if you are designing these connections using Ram Connection, moments won't be considered in the bolted double angle connection design.

 

[dozer]

If you're talking about an all-bolted double-angle connection like you would find in Table 10-1 of the AISC Steel Construction Manual, 14th edition (may be same table in other editions but that's the one that's on my desk right now), then that is considered a simple shear connection (no moments). I suggest you look through all of Part 10 of AISC.