Strengthening of aluminium and stainless steel tubular sections with fibre-reinforced polymer

Strengthening of aluminium and stainless steel structural tubular sections using adhesive bonded fibre-reinforced polymer (FRP) subjected to web crippling has been investigated. Aluminium and stainless steel tubular sections may experience web crippling failure due to local concentrated loads or reactions. The web crippling strength can be enhanced by strengthening the webs of the sections in localized regions. The current international specifications of aluminium and stainless steel structures do not provide web crippling design rules for strengthening of tubular sections. Therefore, there is a need to develop safe and reliable web crippling design rules for FRP strengthened aluminium and stainless steel structures. An extensive test program was performed on FRP strengthening of aluminium and cold-formed stainless steel tubular sections subjected to web crippling. The test specimens consisted of 6061-T6 heat-treated aluminium alloy, ferritic stainless steel type EN 1.4003 and lean duplex type EN 1.4162 square and rectangular hollow sections. A total of 254 web crippling tests was conducted in this study. The tests were performed on eighteen different sizes of tubular sections which covered a wide range of web slenderness (flat portion of web depth-to-thickness) ratio from 6.2 to 62.2. The web crippling tests were conducted under the four loading conditions according to the American Specification and Australian/New Zealand Standard for cold-formed steel structures, namely End-Two-Flange, Interior-Two-Flange, End-One-Flange and Interior-One-Flange loading conditions. The investigation was mainly focused on the effects of different adhesive, FRP, surface treatment, widths of FRP plate and web slenderness of tubular sections for strengthening against web crippling. Six different adhesives, six different FRPs, two different surface treatments, three different widths of FRP plate were considered. It was found that the web crippling capacity of aluminium tubular sections are significantly increased due to FRP strengthening, especially for those sections with large value of web slenderness. The web crippling strength can be increased up to nearly 3 times using the appropriate adhesive and FRP for aluminium tubular sections, whereas the web crippling strength can be increased up to 51% and 76% for ferritic and lean duplex stainless steel tubular sections, respectively. The finite element models for FRP strengthened aluminium and stainless steel tubular structural members subjected to web crippling were developed and calibrated against the experimental results. The debonding between FRP plate and aluminium or stainless steel tubes was carefully modelled using cohesive element. It is shown that the calibrated model closely predicted the web crippling strengths and failure modes of the tested specimens. An extensive parametric study included 212 web crippling specimens was carried out using the verified finite element models to examine the behaviour of strengthened aluminium and stainless steel tubular sections subjected to web crippling. Design equations are proposed to predict the web crippling strengths of FRP strengthened aluminium and stainless steel tubular sections based on the experimental and numerical results. The web crippling strengths obtained from the tests and numerical analysis were compared with the design strengths calculated using the proposed equations. The reliability of the proposed design rules was evaluated using reliability analysis.

並列關鍵字

Tubular steel structures ； Fiber-reinforced plastics

國際替代計量

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