Understanding Torsion Design for Cold-Formed Steel Members
Cold-Formed Steel Research Consortium (CFSRC) Colloquium
Design provisions for combined bending and torsion were introduced in the North American Specification for Cold-Formed Steel Design in 2007, and more recently in the Australian/New Zealand Standard 4600:2018. The purpose of this paper is to enlighten the engineer on the application of these provisions through the use of a design example. Multiple methods of calculating and approximating bimoments and the resulting longitudinal warping stresses are presented and compared. New AISI provisions were recently approved which establish bimoment strength and an interaction equation for combined bending and torsion. Other research is underway to refine the bimoment strength with consideration for local instability. hese are explored as an extension of the design example.