Applies To
	Product(s):	STAAD.Pro
	Version(s):	ALL
	Environment:	ALL
	Area:	Steel Design
	Subarea:	American Design Codes
	Original Author:	Modestas Turulis, Bentley Technical Support Group

Why design takes a lot of time when torsion checks as per DG9 are considered for AISC 360-10 code?

When the torsion design as per AISC Unified DG-9 is performed (design parameter TORSION 1 is used), a lot of additional calculations during the design must be done and that requires a lot of time. In order to reduce this time, the user has to consider a couple of things:

1) Assign TORSION 1 command only to these members which you really want to check for torsion. Other members should have a TORSION 0 parameter assigned;
2) Have a clear idea on the load combinations you want to include for the torsion check. LOAD LIST command should be used to set up this load combinations.

AISC 360-16 design routine has been updated to perform the torsion design much faster, so you might want to AISC 360-16 design code instead of AISC 360-10.