Tests of carbon fibre–reinforced polymer strengthened cold-formed stainless steel tubular sections subjected to web crippling

Abstract

A total of 67 web crippling tests were conducted on carbon fibre–reinforced polymer strengthened cold-formed stainless steel square and rectangular hollow sections in this article. Several carbon fibre–reinforced polymer strengthening schemes were adopted, such as strengthened with carbon fibre–reinforced polymer sheets, strengthened with carbon fibre–reinforced polymer plates and strengthened with anchored carbon fibre–reinforced polymer plates. Two loading conditions of end-two-flange and interior-two-flange have been considered. The tests were performed on five different tubular section sizes which covered a slightly wide range of measured web slenderness ratios from 18.70 to 68.41. The effects of carbon fibre–reinforced polymer length, number of carbon fibre–reinforced polymer layers and carbon fibre–reinforced polymer strengthening schemes on the strength enhancement have been discussed based on the test results obtained from this study. It was found that the web crippling capacity of stainless steel tubular sections can be obviously increased by carbon fibre–reinforced polymer strengthening, especially for those sections with large values of web slenderness under end-two-flange loading condition. However, the strengthening enhancement of carbon fibre–reinforced polymer sheets and carbon fibre–reinforced polymer plates is quite limited due to the debonding between stainless steel tube and carbon fibre–reinforced polymer. The anchored carbon fibre–reinforced polymer plates can effectively delay or totally prevent the debonding failure. The web crippling behaviour of cold-formed stainless steel square and rectangular hollow sections strengthened with anchored carbon fibre–reinforced polymer plates has been significantly improved. Finally, the web crippling test results obtained from this study are compared with the current design strengths.