Direct Strength Design of Cold-formed C-sections in Combined Bending and Shear

The paper describes a research program including tests on both plain C- and SupaCee ® purlin sections in combined bending and shear, and bending only. The high strength SupaCee ® profile steel sections contain additional return lips and web stiffeners which enhance the bending and shear capacity of the sections. They are used widely in Austra lia as purlins in roof and wall systems. The tests were performed at the University of Sydney with and without straps on the flange and thus allowed distortional buckling in the latter case. Design methods for these sections are normally specified in the Australian/New Zealand Standard for Cold-Formed Steel Structur es or the North American Specification for Cold-Formed Steel Structural Memb ers. Both the Effective Width Method (EWM) and the Direct Strength Method (D SM) can be used for the design of C- sections although rules for the DSM in combined bending and shear are not provided in either standard/specificati on. New DSM design rules for C-sections in shear both with and without tension field action are presented and discussed in a separate paper at this conference. This paper proposes DSM design rules for C-sections in combined bending and shear both with and without the effect of distortional buckling included. Both series of test results are compared with the proposed design rules