Rotated Beam Connection Design

[CVG0]

Hello all,

I am designing connections for a small project with rotated beams to accommodate a slope. They EOR and their fabricator decided it would be easier to just rotate the beams to accommodate the slope rather than account for the slope in the connections of the beams on top. After some discussion on this matter, everyone agreed it would be easier to rotate the beams. My question is about the connections for the rotated beams to HSS columns. The beams are rotated a maximum of 5 degrees and the EOR has provided shear end reactions. What considerations for other forces do I need to consider in this situation what is the best way to calculate these forces?

At first I thought about just calculating a moment like this: bf/2 * V = moment, but that seems overly conservative. Then I thought about calculating the distance from the center of the beam with a 5 degree line passing through and multiplying by the shear (that probably doesn't make much sense). dist = tan(5degrees) * d/2, moment = dist * V. That yields a much lower moment. I'm not sure if either method is correct.

Any thoughts on this would be appreciated.

 

[HTURKAK]

If the rotated beam loading is vertical ,( probably yes) , the rotated beam will be subjected to two loadings . ( components of vertical loading ) and probably the design of rotated beam will be more tricky than HSS column. The support reactions should be not only Vyy but also Vxx, Mxx, Myy .

I would prefer to keep the beam horizontal and use tapered shim.

 

[KootK]

If your load is shown oriented correctly, I would just throw a rotated single plate shear tab on the column for the connection and design it per usual. No moments. Perhaps I am missing something.

 

[CVG0]

If your load is shown oriented correctly, I would just throw a rotated single plate shear tab on the column for the connection and design it per usual. No moments. Perhaps I am missing something.

That was my first thought too. The EOR shows end reactions on the drawings which I am assuming it is oriented in the plane of the member as shown above. I was thinking of assuming the worst case scenario which is that the shear is perpendicular to the ground and a moment would be generated, but I don't know the correct way to estimate this. Perhaps I should just ask the EOR if there is moment generated in their model for these.

 

[EngDM]

I agree with KootK, however I think the load drawn isn't necessarily correct. If it is gravity loads it should be along the vertical axis and then broken up into a Vxx and Vyy component, which will generate a twisting moment.

Maybe OP can clarify a bit further.

 

[dold]

I think it would be worth discussing the magnitude of the load. "small project" does that mean small loads? Also 5 degrees is borderline "might just ignore this", depending on the magnitude of the load. I'd probably just take the "horizontal" component of the reaction (component that would bend the shear tab about its weak axis) and multiply by ~3" to find that weak axis bending moment.

 

[CVG0]

I think it would be worth discussing the magnitude of the load. "small project" does that mean small loads? Also 5 degrees is borderline "might just ignore this", depending on the magnitude of the load. I'd probably just take the "horizontal" component of the reaction (component that would bend the shear tab about its weak axis) and multiply by ~3" to find that weak axis bending moment.

Most cases are <10k. Worst case is 35k & 3 degrees rotation. Your method would yield sin(3)*35k*3in/12in/ft = 0.46 k-ft. Which is pretty much negligible.

 

[KootK]

I, too, would not sweat the 5 degree tilt for modest loads. Ours is a game of approximation, always and forever.