Torsional design of open sections to AISC code 1

[Ussuri]

I have a question regarding the design of open sections under torsional loading in accordance with AISC 2005 spec.

Section H3, clause 3 covers torsion of non HSS members. It gives three separate conditions (local yielding, shear and buckling) which must be met. It states this must be done 'by analysis'. The commentary expands on this slightly by stating the analysis should be done using straight forward structural mechanics, for instance using torsional theory and first principles. Which is covered in numerous textbooks such as Salmon and Johnson.

In the UK the Steel Construction Institute have a supplementary publication for torsional design of open sections in accordance with the UK steel codes. This publication takes the theory and codifies it for use with the existing steel code. It makes it simpler and uses the capacity equations already in the code, albiet modified to include the torsional effect.

Does the AISC have a similar publication or is the standard approach for these cases to go back to first principles?

 

[IceNine]

http://www.aisc.org/store/p-1585-design-guide-9-torsional-analysis-of-structural-steel-members.aspx

Design guide #9 'Torsional Analysis of Structural Steel Members'

pdf is free for AISC members.

 

[JoshPlumSE]

For what it's worth, I have both the AISC design guide #9 and the british publication (SCI's Design of Members Subject to Combined Bending and Torsion).

Not surprisingly, the theory is virtually idential for open sections. However, the design procedures seem to be a bit more complex (and conservative) in the British code.