Experimental study on the seismic performance of thin-walled CFST superimposed shear walls with different column widths

Prefabricated concrete-filled steel tube shear walls leverage the advantages of both concrete and steel and have found applications in high-rise buildings and regions with high seismic activity. This paper proposes a type of thin-walled concrete-filled steel tube with superimposed shear walls (CFST-SSWs) that can be conveniently installed on-site to improve construction efficiency and quality. Four full-scale specimens were experimentally tested under constant axial forces and lateral cyclic loads to examine their seismic performance. The two main variables during tests were the end column type and the CFST column width. The X-shaped crack in the CFST-SSWs specimen only extended to the edge of the superimposed wall, while that of the cast-in-place concrete column composite shear wall specimen connected to a crack in the end column. As the widths of the CFST column increased, the ductility increased to 13.47%, and the bearing capacity increased by an average of 14.5%. The average ductility coefficients of the specimens ranged from 2.23 to 3.95, and the CFST-SSWs showed moderate ductility. Increasing the width of the CFST column had little effect on its overall energy dissipation capacity in the early stage, but helped slow the stiffness degradation and intensity degradation of CFST-SSWs. It also significantly increased the ultimate inter-story displacement angle. A calculation model was developed to predict the CFST-SSWs’ cracking load, and experimental data were used to validate the model’s accuracy.