A sample model built for verifying the torsion check under the AISC 360-10 code check, and seems there are some problems:
1. When a round HSS profile used, a warning appears in the output ANL file saying “WARNING- TORSION DESIGN OF MEMBER # 1 NOT POSSIBLE AS IT HAS NO TORSIONAL FORCES/STRESSES.”, however the torsional force does apply and torsional stress does exist, and it seems actually the torsion does be checked. For details please see pictures as follows:
2. When a AISC W shape profile used instead of a round HSS profile, the same warning appears in the output ANL file but this time everything is the same as the round HSS example shown above except that there is no any sign of performing torsion check as the warning tells.
Hi Structural Fans,
As per Section 220.127.116.11 of the Technical Reference manual, only member loads of the types listed are considered for torsion. The joint load does induce a torsion but is not considered in the DG9 check. Please apply a concentrated torque as a member load near the end of the member when using the DG9 torsion check (i.e., TORSION 1).
Jason Coleman, PE
Bentley Systems Senior Manager Technical Content