Abstract
Based on the plastic-damage constitutive model of concrete and elastic-plastic mixed strengthen constitutive model of steel material, the finite element software ABAQUS was used to build an elaborate 3D finite element (FE) solid model and perform pseudo-static analysis of terminal stirrup-confined concrete-filled rectangular steel tubular columns (SCFT) in this study. The FE model considers the confinement effect of both the steel tube and the stirrups exerting on the core concrete and the cumulative damage effect due to the horizontal cyclic load. Good agreement was achieved between the FE results and the existing quasi-static experimental results regarding to the load-displacement hysteretic curves, load-displacement skeleton curves, load-strain ratio curves, and local buckling-displacement curves. Based on the validated model, a total of 315 full-scale column models were established and extensive parametric analysis was conducted. The results indicate that: (1) When the axial compression ratio n is up to 0.8, the seismic behavior of rectangular CFT columns with bidirectional stirrups is significantly better than those counterparts with ring stirrups having the same volume stirrup ratio. (2) When the longitudinal compressive strain of steel tube reaches 30 times of the yield strain, plastic hinge is formed at the end of SCFT column and the stirrups can effectively reduce the plastic hinge length. A formula of plastic hinge length suitable for different axial compression ratios and equivalent stirrup ratios is proposed. (3) According to the results of parametric analysis, the seismic structural measures including reasonable equivalent stirrup ratio and region height of terminal stirrups are proposed for different axial compression ratios and strength matching patterns between steel tube and core concrete.
Published Version
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