Experimental and numerical study on retrofitting partially damaged exterior beam-column joints under lateral monotonic loading

Purpose The purpose of this paper is to present an experimental study aimed at improving the performance of seismically designed reinforced concrete (RC) beam-column joints (BCJs) with partial failure. Design/methodology/approach Various retrofitting methods, including carbon fiber reinforced polymer (CFRP) sheets and steel plates (SPs), were tested. Six specimens were subjected to constant vertical and increasing lateral monotonic loads until failure. Five of the specimens failed partially, reaching up to 85% of the ultimate load of the control specimen. The damaged specimens were repaired with epoxy resin and retrofitted using different techniques: SP, CFRP sheets and CFRP sheets with strips. Retrofitted specimens were tested using the same loading protocol. Findings The results of this study showed that CFRP retrofitting improved peak load, stiffness and energy absorption by up to 25.7%, 46.3% and 47.8%, respectively, compared to the control specimen. SP improved these metrics by up to 58.0%, 44.8% and 71.4%, respectively. SP showed significantly greater improvements in peak monotonic load, stiffness and energy absorption compared to CFRP, indicating superior performance in resisting monotonic loads and absorbing energy. Originality/value These retrofitting methods significantly enhance joint strength, seismic resistance and energy absorption. Additionally, the experimental results were validated using a highly accurate numerical model.