Compression Tests of Cold-Reduced High Strength Steel Channel Columns failing in the Distortional Mode (No. R825)

Abstract

This report describes a series of compression tests performed on lipped channel section columns fabricated from cold-reduced high strength steel of thickness 0.42 mm with nominal yield stress 550 MPa. The test results presented in the paper are the third stage of an Australia Research Council research project entitled “Compression Stability of High Strength Steel Sections with Low Strain-Hardening”. A range of lengths of lipped channels with intermediate stiffeners in the web and the flanges were tested between fixed ends to determine the strength of the sections. For the lipped channel sections, the failure resulted from local and distortional buckling with interaction between the modes. The tests indicated that distortional buckling and the interaction of local and distortional buckling may have a significant effect on the strength of the sections formed from such thin steel. The report presents the results obtained experimentally and theoretically using the effective width method and the direct strength method. Two new design methods are proposed to account for the adverse interaction of local and distortional buckling.