Global buckling capacity of cold-rolled aluminium alloy channel section beams

Abstract

The paper presents a series of four-point bending tests investigating global buckling of cold-rolled aluminium alloy channel beam members. These types of sections have been commercially fabricated in Australia using a roll-forming process as distinct from the usual extrusion process. A total of twenty specimens of three commercially available channel sections with two thicknesses and various lengths were tested at the University of Sydney. Mechanical properties of aluminium alloy 5052 material were reported on the basis of tests of tensile and compression coupons cut longitudinally from both flat and corner parts of the cross-sections. Prior to the testing of beams, initial geometric imperfections of each specimen were measured using a laser scanning method. A dual-actuator test rig was specially designed to maintain the load vertically applied through the shear centre of the channel section throughout the test. Flexural-torsional and distortional buckling modes were observed including interaction of these modes. The paper also details finite element (FE) models developed using the commercial ABAQUS software package to simulate the behaviour and ultimate member buckling capacities of cold-rolled aluminium alloy channel beams. The FE models with the incorporation of measured properties and actual imperfections are verified against the experimental results indicating good agreements. The test results are then compared with the design strength predictions from current specifications. The calibrated model results are laying the foundation for undertaking parametric studies and proposing new design rules for the global and distortional buckling capacities of these types of cold-rolled aluminium alloy channel sections in the subsequent work.