Experimental investigation on seismic behavior of damaged self-centering friction beam-column joints after repair

Abstract

Self-centering beam-column joints are an effective strategy to improve the seismic resilience of frame structures. Extensive research has been conducted on the seismic performance of newly constructed self-centering joints, involving experiments, theoretical analyses, and simulations. Nevertheless, less attention has been paid to evaluating the seismic resilience of self-centering joints after repair. To address this gap, this paper presents a series of experiments to investigate the mechanical properties of damaged self-centering friction beam-column joints (SCFJ) after repair. Three SCFJs damaged by cyclic loading are repaired using epoxy injection, CFRP wrapping, and replacement concrete. The repaired joints are then subjected to cyclic loading under the same conditions as the original loading. A comprehensive analysis is conducted of the hysteretic curve, skeleton curve, energy dissipation, stiffness degradation, and residual displacement of both the original and repaired SCFJs. The results show that the repaired SCFJs maintain their commendable self-centering capacity. Specifically, the replacement concrete method is the most effective in restoring the initial seismic performance of the SCFJs. The epoxy injection method is the fastest repair method and successfully restore the SCFJ to approximately its original ultimate strength and approximately 85% of its energy dissipation and self-centering capacity. The CFRP wrapping method is able to largely restore the self-centering capacity of the SCFJ to its original level, but with a notable decrease in stiffness.