Lintel Beam Design

[Escobales]

Hello Fellow Engineers:

I am interested in studying homogeneous non-symmetrical sections subjected to torsion. For example, built-up sections, (I-beams), having the bottom flange extended to carry brick. So far, I have studied the modified flexure analogy presented by Salmon & Johnson 4th Edition (Steel Structures) but I seem not be able to find anything related to torsional rotation other than the AISC Steel Design Guide Series 9. What about calculating deflections. Are the standard procedures still applicable for this non-symmetrical sections? I think not. Any suggestions?

 

[Ron]

The torsional response of the primary section of the beam is the same without regard to the source of the torsion. Just because you have a built-up section doesn't change this. Hanging a ledge angle off the side of a beam produces torsion in the beam that would be the same as if you placed cantilever outriggers off the beam and loaded those. In short, the AISC torsional parameters still apply.

 

[Escobales]

RON,

Thanks for your message. You meant that I can calculate the deflection using the standard equations regardless that this section is unsymmetrical and that the load does not passes thru the shear center? Shouldn't I used the principal moments of intertia, Iu & Iv, to calculated this values? What about the rotation of the beam. What will the allowable rotation in radians will be?