NONLINEAR ANALYSES OF THIN-WALLED CHANNEL SECTION COLUMNS

The paper presents a detailed comparison of nonlinear analyses of thin-walled channel section columns with tests. The columns are analysed as beam-columns having nonlinear constitutive relationships. The constitutive relationships are obtained firstly, by assuming elastic material behaviour and allowing local buckling of both flanges and web, and secondly, by assuming elastic-plastic material behaviour and confining local buckling deformations to the web. Based on the comparison, including theoretical and experimental load-shortening and load-deflection curves, it is concluded that the nonlinear theory generally closely agrees with the tests. The paper also investigates the applicability of combining an elastic nonlinear analysis with a spatial plastic mechanism analysis to describe the structural behaviour both before and after the ultimate load. The question of when this combination can be expected to accurately describe the column behaviour over the full loading range is discussed. A separate section compares theoretical ultimate loads with test strengths. The nonlinear analyses employed in the paper provide ultimate loads which agree with the test strengths to within 2% on average where primary local buckling occurs in the web of the channels, and 11% on average where primary local buckling occurs in the flanges of the channels.