Experimental and analytical study of thin-walled stirrup-confined CFST piers under pseudo-static loading

Abstract

A pseudo-static test study was conducted to investigate the seismic performance of stirrup-confined square concrete-filled steel tube (CFST) bridge piers. Furthermore, a refined finite element model (FEM) that considers the cracks in concrete and the ductile damage of steel was established. Based on this, a refined restoring-force model for stirrup-confined square CFST bridge piers that takes into consideration the pinching effect coefficient was proposed. The research results show that, compared with traditional square CFST bridge piers, stirrup-confined square CFST bridge piers exhibit a superior seismic performance, as their yield load, horizontal peak load, cumulative energy dissipation, and elastic stiffness are higher by 49.3%, 42.8%, 24.1%, and 15.1%, respectively. The axial compression ratio, yield strength of the steel tube, compressive strength of concrete, aspect ratio, and width–thickness ratio have a significant effect on the seismic performance of stirrup-confined square CFST bridge piers, while the yield strength of the stirrup has little influence on their seismic performance. The proposed refined restoring-force model for stirrup-confined square CFST bridge piers that takes into consideration the pinch effect coefficient has high accuracy and is in good agreement with the FEM results.