Sloping Cold Formed Metal Rafter Connection Question

[bigmig]

I am new to cold formed metal framing, and have been searching for a detail I would think is pretty common. The sloping, metal C joist bearing condition.
I have found some generic details describing the stacking condition, i.e. cold formed steel joist ON TOP of the primary support.

What happens if they are in the same plane and need to align flush relative to each other? I have attached a sketch to describe this.
In wood, we have sloping connectors, or we cut a birdsmouth into the rafter. How does it work with Cold Formed steel?

 

[hokie66]

That is an unfortunate alignment, but I would just provide a plate extending out from the beam web and up to the cold formed member.

 

[SAIL3]

that is an awkward connn...I would try clipping the C-section so that it rests on the WF and then check the remaining web for shear & mom and reinf as necessary...

 

[JAE]

You could add an angle to the top of the flange with an upturned leg located at the flange tip.
Then use a clip angle to fasten each and every C rafter to the angle.

However, this will induce torsion on the WF (lots of twist) and you'd want to have some means of laterally bracing the WF against the twist.



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[DaveAtkins]

I would take another cold formed section (it might need to be very shallow, like 2-1/2" deep, and set it horizontally on top of the wide flange, so that it crosses the centerline of the wide flange and laps (back to back) with the sloping rafter. You will need enough screws connecting the two cold formed members together to resist shear and moment. In short, I am saying lap a shallow piece of cold formed steel with the rafter.

DaveAtkins

 

[msquared48]

Get a new Architect.

This is the perfect situation to apply the KISS principle. The steel beam needs to be dropped so that a sloping rafter connection can be used.

Mike McCann
MMC Engineering

 

[Agent666]

In the past I have provided an extended cleat with a 4 bolt arrangement (2 bolts by 2 bolts) and effectively made a moment connection and designed the connection and purlin for the resulting load due to the eccentricity of the purlin stopping short of the shear centre of the beam.