Web crippling of aluminium tubular structural members strengthened by CFRP

Aluminium tubular structural members may experience web crippling failure due to localise concentrated loads or reactions. This paper presents a test programme on strengthening of high strength aluminium tubular structural members using externally bonded carbon fibre-reinforced polymer (CFRP). A series of tests on CFRP strengthened aluminium square and rectangular hollow sections subjected to web crippling is presented. The web crippling tests were conducted under four loading conditions of End-Two-Flange, Interior-Two-Flange, End-One-Flange and Interior-One-Flange. A total of 48 web crippling tests was conducted in this study. The investigation was mainly focussed on the effects of web slenderness of aluminium tubular sections on CFRP strengthening against web crippling. The tests were performed on eight different sizes of square and rectangular hollow sections which covered a wide range of web slenderness (flat portion of web depth-to-thickness) ratio from 6.2 to 62.2. The test specimens were fabricated by extrusion from 6061-T6 heat-treated aluminium alloys. Material properties of the aluminium sections were obtained from tensile coupon tests. Most of the strengthened specimens were failed by debonding of CFRP plate from the aluminium tubes. Three main failure modes were observed in the tests, namely the adhesion, combination of adhesion and cohesion, and interlaminar failure of CFRP plate. The failure loads, failure modes and the load-web deformation behaviour of the aluminium sections are also presented. It was found that the web crippling capacity of aluminium sections are significantly increased due to CFRP strengthening, especially for those sections with large value of web slenderness ratio. (C) 2012 Elsevier Ltd. All rights reserved.