Web crippling of aluminium alloy channel sections with flanges restrained

This paper describes an investigation of web crippling behaviour of aluminium alloy plain and lipped channels with flanges restrained. A total of 340 data is presented that include 52 test results and 288 numerical results. A series of tests was conducted on plain and lipped channels fabricated by extrusion using 6063-T5 and 6061-T6 heat-treated aluminium alloys under end-two-flange (ETF) and interior-two-flange (ITF) loading conditions. The concentrate loads were applied by means of bearing plates. The flanges of the channels were either bolted (fastened) to one or two bearing plates. A finite element model was developed and verified against the experimental results. Geometric and material non-linearities were included in the finite element model. It was shown that the finite element model closely predicted the web crippling strengths and failure modes of the tested specimens with flanges restrained. Hence, the finite element model was used for an extensive parametric study of cross-section geometries, and the web slenderness value ranged from 24.0 to 207.3. The test results and the web crippling strengths predicted from the finite element analyses were compared with the design strengths obtained using the American, Australian/New Zealand and European specifications for aluminium structures. A unified web crippling equation with new coefficients for aluminium alloy channels with flanges restrained under ETF and ITF loading conditions is proposed in this study. Since two failure modes of web buckling and web yielding were also observed in the aluminium plain and lipped channels with flanges restrained, design rules of web crippling strengths are also proposed by considering the lesser of the web buckling strength and web yield strength.