Experimental investigation of initially damaged beam column joint retrofitted with reinforced UHP-HFRC overlay

Abstract

The present experimental study investigates the effectiveness of ultra-high-performance hybrid fiber reinforced concrete (UHP-HFRC) overlay for retrofitting the initially damaged reinforced concrete beam column joint (BCJ). Eight control BCJ specimens are tested under quasi static reverse cyclic loading. The ‘Park and Ang’ damage indices are calculated for four distinct damage states, i.e., complete, severe, moderate and slight from the load displacement curve of the control specimen. Each set of specimens were subjected to reverse cyclic loading to achieve their respective damage states. Each damaged specimen is then retrofitted using the wire mesh as reinforcement in the UHP-HFRC overlay. The retrofitted specimens using reinforced UHP-HFRC overlay exhibited the improvement in the load-carrying capacity, ductility, drift capacity, energy dissipation, equivalent viscosity damping, stiffness retention at higher drift, and lower strength degradation for a given damage level. However, the performance of the retrofitted BCJ specimens significantly depends upon the initial damage state of the BCJ. The improvement in the performance of the retrofitted specimen gradually decreases as the initial damage state of BCJ shifted from slight to complete; nevertheless, the performance of all the retrofitted samples is better than the controlled specimen.