Confinement model for concrete in circular and square FRP–concrete–steel double-skin composite columns

Abstract

This paper presents a new design-oriented model for predicting the ultimate failure conditions of concrete in fiber-reinforced polymer (FRP)–concrete–steel double-skin tubular columns (DSTCs). An experimental test database consisting of all the axial compression test results for DSTCs available in the published literature is presented and used to assess the performance of four existing models to predict the compressive strength and ultimate axial strain of concrete in DSTCs. A new concrete confinement model that incorporates the failure mode of the inner steel tube is proposed. Both the strength and strain predictions of the proposed model are in close agreement with test results to an accuracy better than the existing models.