Rotational deflection of beams in torsion

[Bubik]

Hi everyone,

I have an I beam in torsion due to supporting a section of a masonry cladding. What limit of rotational deflection ( in degrees) do you use? I read that it is 2 degrees, well in the UK at least. Would you share your thoughts on this?

Thanks

 

[jochav52802]

Hello Bubik,

This question came up the other day in our office as well, but I've not seen any such criteria before based on rotation; however, check out the attached Engineering Journal document from AISC which covers serviceability limits for various components. I would think that you could use the implicit rotations from the out-of-plane deflection limits as a means to come up with the rotational limits for those elements.

Enjoy!

 

[BAretired]

If the thing being supported is causing torsion in the beam, it must be at some fixed eccentricity to the centroid of the beam. Instead of focusing on the angle, consider the movement of the element being supported. 2^o is equivalent to 0.0349 radians. If e = 10", the item being supported moves downward a distance of 0.349" at midspan of the beam. Would that much deflection be of concern?

BA