Aluminium alloy channels subjected to web crippling

Abstract

This article reports experimental and numerical investigations of aluminium alloy plain and lipped channels subjected to web crippling. A total of 240 data are presented that include 24 test results and 216 numerical results. A series of tests was conducted first on channels fabricated by extrusion using 6063-T5 and 6061-T6 heat-treated aluminium alloys under end-two-flange and interior-two-flange loading conditions. The concentrate transverse loads were applied by means of bearing plates. The flanges of the specimens were not fastened (unrestrained) to the bearing plates. A non-linear finite element model is then developed and verified against 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. Hence, the 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 analysis were compared with the design strengths obtained using the American, Australian/New Zealand and European specifications for aluminium structures. An empirical unified web crippling equation with new coefficients for aluminium alloy channels under end-two-flange and interior-two-flange loading conditions is proposed. Since two failure modes of web buckling and web yielding were observed in the tests, the web crippling strength is also predicted using the proposed theoretical design rules for channels. The web crippling strength is the lesser of the web buckling strength and web yield strength.