Experimental study on seismic damage behavior of high strength concrete-encased concrete-filled steel tube composite columns

To investigate the effects of different loading systems, axial compression ratio, volume stirrup ratio, the ratio of steel tube diameter to height and stirrup form on the seismic damage evolution and seismic performance of high-strength concrete-encased concrete-filled steel tube composite columns, 11 composite columns and 1 reinforced high-strength concrete column were tested under horizontal bearing capacity loading. The results show that the seismic performance of the composite columns is better than that of conventional reinforced concrete columns. With the increase ofloading cycles and displacement amplitude, the cumulative damage of composite columns increases, and the bearing capacity, stiffness and ductility decrease. With the increase of axial compression ratio, the bearing capacity of the composite columns improves, but the later deformation capacity and energy dissipation capacity decrease, and the strength and stiffness degradation accelerates. The seismic performance of the composite columns improves significantly by increasing the volume stirrup ratio within the range of 1.33%~1.63%. With the increase of the ratio of diameter to height, the bearing capacity of the composite column increases slightly, but the damage develops rapidly in later period. The composite column with octagonal stirrup has better seismic performance than that in well-shaped tensile reinforcement. © 2020, Editorial Board of Journal of Huazhong University of Science and Technology. All right reserved.