Finite Element Analysis on Seismic Performance of Socketed Joints for Concrete-filled Steel-tubular Bridge Piers

Concrete-filled-steel-tubular (CFST) bridge piers have become a critical component in bridge structures due to their excellent bearing capacity, ductility, and seismic performance. To investigate the seismic performance of socketed joints in concrete-filled steel tube (CFST) bridge piers, this study conducts parametric numerical analyses method to examine the effects of socket embedment depth, steel-tube strength, steel-tube thickness, and infilled-concrete strength on the seismic behavior of socketed joints. The research findings indicate that as the socket depth increases, failure transitions gradually from foundation failure to column-base bending failure. It has been demonstrated that increases in steel pipe thickness or strength result in significant growth trends in both the initial stiffness and peak horizontal load capacity of the pier. Specifically, an increase in steel pipe thickness of 1 mm has been shown to enhance initial stiffness by approximately 8%~9% and to boost peak load capacity by 2%~6%. For each grade increase in concrete strength, initial stiffness and peak load-carrying capacity increased by over 7% and 4%, respectively. This indicates that high-strength concrete effectively enhances the overall seismic performance of socket-type steel-concrete composite bridge piers. This study clarifies the influence patterns of key parameters on the seismic performance of socket joints in concrete-filled steel tube bridge piers. It demonstrates that optimizing socket depth, appropriately increasing steel pipe thickness and strength, and enhancing concrete strength can effectively improve joint seismic performance. The research findings provide theoretical basis and data support for seismic design, parameter optimization, and engineering application of socket joints in steel-concrete composite bridge piers.