Software that accounts for Torsion in WF's 1

[dozer]

Are there any structural programs that account for torsion in wide flanges when code checking per AISC 13th edition. I use STAAD.Pro and it does not. It does for the 9th edition but they decided AISC 13th edition was too vague so they just don't check.

 

[ToadJones]

You sure STAAD doesn't for the 13th?
I think it does.

 

[a2mfk]

Off the top of my head, if your torsion is under a certain level I think you can ignore it. I also remember that the interaction equations for this aren't bad, may be easiest to design it in STAAD and then run some hand calcs for torsion.

 

[JoshPlumSE]

The 13th edition's treatment of WF torsion cannot be reasonably implemented in any software program. The problem as I see it is an inconsistency with the rest of the code. As written, the code would have you move from a moment capacity of Mp to a moment capacity of My when you have even the smallest iota of torque in the member. You can't have that type of large discontinuity in your combined stress equations.

In RISA, we consider torsion in wide flanges for the 13th edition. But, we use the recomendations of the AISC Design Guide on Torsion. Those recomendations seem more rational to me. The recommendations consist of calculating torsional shear stresses and torsional warping normal stresses and adding them to the existing flexural shear stresses and weak axis bending stresses. Done in this manner this is not any discontinuity between the combined stress equations with or without torsion.

Also, FWIW, I think the reason why the code is so conservative with torsion of wide flanges is because it is assuming that whatever analysis was done is ignoring the torsional warping effects on the wide flange members. Since these can be significant, it makes sense to be conservative.

Therefore, ewhen a program like STAAD (which I don't believe copnsiders torsional warping effects), I would always recommend running a side calculation related to warping effects.... at least until you are comfortable with what your program does related to warping.

 

[dozer]

Toad, STAAD does not include torsion in AISC 13th ed code checks of wide flanges. It doesn't even have the TORSION design parameter for AISC 360-05 (13th ed.).

Josh, STAAD does allow you to the control the warping restraint at the end of beam, so I assume this means they consider torsional warping effects. I know if you model a cantilever and torque it, it makes a big difference in rotation whether you have warping restraint set or not. The default is not.

Anyway, so it sounds like RISA is at least taking a stab at it. Good for you. Anybody else know what other programs are doing?