Coping to force pin action in masonry bolted moment connection

[David Deck Guy]

I need a little bit of a sanity check on this. I'm installing a new pergola on an existing masonry. If I run this thing as a moment connection, the loads always blow up my anchors. I would like this to be a pin. My first thought was to bolt the HSS to two angles, which would then be epoxy anchored to the masonry parapet. Unfortunately, as they tend to do, the architect has already vetoed this for "aesthetic" reasons. Two options come to mind:

1. I am overthinking this, and its fine to model this as a pin.

2. Cope the flanges and web until the moment capacity of the coped section is less than the moment capacity of masonry connection. This gets complicated when factoring in combined loading, where the shear can fail the connection if it also included a reduced moment.

Any advice on this would be greatly appreciated, as I suspect its going to be a detail I use quite often moving forward.

 

[Tomfh]

You're overthinking it if you're considering notching the beam to induce a plastic hinge.

Just make it a flexible enough connection that it wont break the masonry - e.g. flexible two bolt end plate.

 

[David Deck Guy]

Thank you.

Flexible enough, meaning:
- no stiffeners (obvious)
- keep the base plate thin
- make the base plate long enough that the plate will go plastic in bending before really cranking on the bolt

?

 

[Tomfh]

Those are all things that will make the connection flexible.

If you make it flexible it won't behave as a moment connection.

You don't necessarily have to make it so weak that it will yield prior achieving the peak moment at the support, it simply has to be flexible enough that it doesn't generate that high moment in the first place.

How big is this pergola anyway if you're shearing off bolts?