Direct Strength Design of Cold-Formed C-Sections for Shear and Combined Actions

The direct strength method (DSM) recently included in the North American Specification and Australian/New Zealand Standard AS/NZS 4600:2005 gives design rules for compression and bending. No rules are presented in this standard for shear or for combined bending and shear. Two series of tests on C-section can be used to develop and calibrate rules for design in shear and for combined bending and shear. These are the University of Missouri Rolla tests of the 1970s and recent tests on high-strength C-sections at the University of Sydney. Both series of tests use a similar test rig, although different levels of tension field action have been observed. Two features researched are the effect of full-section shear buckling (as opposed to web-only shear buckling), and tension field action. Full-section buckling is a feature of the DSM but requires software that can evaluate full sections for shear. The paper proposes DSM design rules for C-sections in shear and for combined bending and shear both with and without tension field action. The test results are compared with the proposed design rules.