Behaviour of short CFRP-steel composite tubed reinforced normal and high strength concrete columns under eccentric compression

The use of steel tubed reinforced concrete (STRC) column maximizes the confinement effectiveness of steel tube as the steel tube is disconnected at the beam-column joint. However, for high-strength and high performance concrete, the confinement from the steel tube would be limited. Also, certain measures need to be implemented to prevent the corrosion of steel tube. Carbon fibre reinforced polymer (CFRP) has the advantages of high strength-to-weight ratio and good corrosion resistance. However, the complicated construction procedures and relatively brittle post-peak behaviour limit its application to new concrete buildings. The combination of CFRP and STRC column is a good alternative to solve the concerning problems. This study experimentally investigated the behaviour of CFRP-steel composite tubed reinforced concrete (C-STRC) columns under eccentric compression. The observed failure modes, load-deformation curves, and load-stress curves of the steel tube and longitudinal reinforcing bars are presented. The test results show that the load capacity and deformability of the C-STRC columns with normal concrete strength are enhanced due to the use of CFRP and steel tube. The plastic stress distribution method was employed to analyse the axial load versus moment interaction curves and the results were found to be generally in good agreement with the test ones.