On the use of the EC3 and AISI specifications to estimate the ultimate load of CFRP-strengthened cold-formed steel lipped channel columns

This paper summarises an investigation carried out to predict the structural behaviour of CFRP-strengthened cold-formed steel lipped channel columns−more specifically, it addresses the applicability of the provisions of Eurocode 3 (EC3) and the AISI Specification (AISI-DSM, direct strength method), both developed for cold-formed steel members, to estimate their load-carrying capacity. It is worth noting that EC3 and AISI-DSM adopt different approaches to perform this task: while the former is based on the “effective width” concept, the latter may adopt the “Direct Strength Method”. First, the most relevant aspects related to the experimental and numerical investigations carried out to obtain “exact” column collapse loads are briefly presented. Then, an extensive numerical study is performed, which is intended to evaluate the benefits of CFRP-strengthening for different CFRP ply configurations, number of CFRP plies and steel yield stresses. After proposing different methodologies to extend the application of the EC3 and AISI-DSM design provisions to CFRP-strengthened cold-formed steel columns, the estimates provided by them are compared with the experimental values. On the basis of these comparisons, some concluding remarks are drawn concerning the merits and shortcomings of extending the domain of application of the current EC3 and AISI-DSM design approaches, so that they may cover also CFRP-strengthened lipped channel columns.