Experimental investigation into FRP-confined concrete-filled steel tubular columns under axial compression

The mechanical behavior of 66 carbon-fibre-reinforced polymer (CFRP)-confined concrete-filled steel tubular (CFST) short columns and 42 non-CFRP-confined CFST short columns under axial compression are studied. The typical failure modes and load–displacement curves of the specimen are obtained, and the stress mechanisms of the specimen are analysed. The effects of fiber-reinforced polymer (FRP) layers, core concrete strength and cross-section forms on the axial mechanical properties of CFST short columns are discussed. The test results show that there is a positive correlation between the improvement coefficient of bearing capacity and the confinement effect coefficient of FRP. Based on the superposition principle, the bearing capacity calculation formulas of circular and square CFST columns without CFRP confinement are proposed. On this basis, taking the confinement effect of FRP into account, the calculation formula of axial bearing capacity of FRP-confined CFST short columns is proposed. The comparison between the calculated values of the model and the measured values of the experiments shows that the model has good prediction effect.