Seismic Performance of Concrete Composite Columns of Ultra-High Performance Concrete Precast Pipe

To investigate the seismic performance of concrete composite columns of ultra-high performance concrete (UHPC) precast pipe under low-cycle repeated loads, three concrete composite columns of UHPC precast pipes and one reinforced concrete (RC) column were subjected to quasi-static tests, so as to analyze the seismic performance of each composite column specimen in terms of damage mode, displacement ductility, energy dissipation capacity, and stiffness degradation under different UHPC strengths and core concrete with or without reinforcement. The analysis results show that the hysteresis curves of the concrete composite column specimens of UHPC precast pipe are fuller, and their damage patterns are basically the same, which are both integral compression-bending damage. Compared with those of the conventional RC columns, the stiffness, yield load, and ductility of the concrete composite column of UHPC precast pipe are improved. With the increase in UHPC strength, the hysteresis curves of the composite column specimens are fuller, and the energy dissipation capacity is enhanced. The residual displacement is small, and the horizontal peak load and displacement ductility coefficient increase by 20.6% and 6.4%, which shows good overall seismic performance. The finite element analysis model of the composite column is established by the ABAQUS program, and the calculation results are in good agreement with the test results. Different axial compression ratios, slenderness ratios, and UHPC strengths are important parameters affecting the seismic performance of concrete composite columns of UHPC precast pipes, which can provide a reference for similar engineering designs.