Design Steel in torsion to AS4100

If you have access to NZS3404 which is pretty much the same as AS4100, then you'll find NZS3404 has a few additional clauses in the commentary section 8.5 related to torsion (least compared to the version of AS4100 amd#1 that is the latest I have).

This information includes some combined actions checks for combining warping torsion and non-uniform torsion, and bending stresses. The remainder of the torsion section is more or less identical to AS4100, but for some reason we have this additional information. Given the similarity of our standards I'd imagine it would be appropriate to use and apply without too many questions being raised.

Otherwise you'd need to resort to some overseas advice like AISC design guide 9, or SCI P385.

Hi Agent, Thanks for your help.
I got induced minor moment, the warping moment and st Venant torsion by using the AISC and SCI but couldn’t find the corresponding formula in AS4100 to applied them for combined actions check.

Unfortunately I don’t have New Zealand standard. Can you please let me know what formula is used for combined actions check in New Zealand one? Thank you very much.

Thank you very much

I was curious and used Space Gass 'design to NZS3404' and it looks like Space Gass doesn't design to torsion regardless. Is there any software that design to torsion by any chance?

'CHECKSTEEL' software will check torsion capacity.

For hollow sections it uses the check of phi*0.6*fy for maximum stress, as in Agent666's post, although expressed in terms of a section capacity (kNm) instead of a stress (MPa).

Similarly, it can also check torsion capacity of angles based on a paper by Trahair:

Trahair, NS 2001, 'Bending, Shear and Torsion Capacities of Steel Angle Sections', University of Sydney Centre for Advanced Structural Engineering Research Report No. R810.

Other than that, it will not check torsion for any other section type.

Thank you. I will have a look