Static analysis of the hysteretic performance of the central columns in subway station enhanced by engineered cementitious composite jacket under high variable axial force

Engineered cementitious composite (ECC), a cement-based composite material known for its high tensile strain and ductility, was utilized to enhance the seismic performance and operational safety of the central columns in vulnerable areas of subway stations. By establishing refined solid finite element models of ECC composite columns and ordinary concrete columns, and conducting dynamic time history analysis on the vertical axial force at the top of the column, a comparative analysis was performed using a static model to determine the difference in hysteretic performance between ECC composite columns and ordinary concrete columns. Furthermore, sensitivity analysis is conducted based on different structural parameters. The results demonstrate that ECC composite columns exhibit significant improvements in bearing capacity, ductility, and energy dissipation, while also reducing stiffness degradation compared to ordinary concrete columns under various vertical variable axial loading conditions. Increasing the diameter of longitudinal reinforcement and reducing the stirrup spacing can effectively enhance the bearing capacity and ductility of columns. Additionally, employing an ECC jacket can effectively improve the shear capacity of the columns. Furthermore, modifying the frequency, amplitude, and phase of the vertical axial force will significantly alter the stress distribution and damage failure of the columns.