Behavior of Cold-Formed SHS Beam-Columns

This paper describes a test program conducted on the behavior of cold-formed, compact square hollow section beam-columns. The tests were conducted in a purpose built test rig capable of applying load and moment in a constant ratio. The test specimens were pin-ended specimens loaded, with varying load/moment ratios, at two different ratios of end moment. The results of the tests were closely simulated using a finite-element program, thereby validating its use in predicting cold-formed tubular beam-column behavior. The finite-element program was then used to find the maximum load and moment capacity, for the section tested, at varying ratios of end moment, from which the corresponding maximum second-order elastic moments were calculated. The results of this numerical investigation are compared with the relevant interaction design rules from the 1990 Australian standard AS4100 and the 1986 American Institute of Steel Construction (AISC) load and resistance factor design (LFRD) specification.