Flexural behavior of high strength concrete filled square steel tube with inner CFRP circular tube

Abstract

This paper investigates the flexural behavior of high strength concrete filled square steel beam with inner CFRP (carbon fiber-reinforced polymer) circular tube by the ABAQUS/Standard solver. In addition, eight specimens were fabricated and tested to investigate the pure flexural behavior. The test data was used to verify the Finite Element Analysis (FEA) modeling and good agreement was achieved in general. Furthermore, the influences of steel yielding strength, concrete strength, steel ratio and the thickness of CFRP on the flexural performance of the specimens were analyzed by FEA. According to the analysis of bending moment versus strain curves, the materials of CFRP, steel and concrete worked well together subjected to pure bending before the CFRP tube ruptured. The results presented in this paper show that these composite beams have a very ductile response because the concrete is confined by the CFRP tube and the steel tube. The beams’ flexural response, including the flexural stiffness and the ultimate load, can be substantially improved by the inner CFRP tube. The parametric studies provide information for the development of formulae to calculate the moment capacity. A comparison of experimental failure loads with the predicted failure loads in accordance with the formulae showed good agreement.