Cyclic behavior of damaged reinforced concrete columns repaired with high-performance fiber-reinforced cementitious composite

A high-performance fiber-reinforced cementitious composite (HPFRCC) prepared with high-volume fly ash is proposed to repair damaged reinforced concrete (RC) columns. This study aims at developing an effective and easy-to-apply repairing technique for RC columns damaged in earthquake. Four columns with 200 mm × 200 mm cross section and 900 mm height were prepared and tested to 85% of the load-carrying capacity under amplitude-increasing lateral loads and a constant axial load. The damaged columns were repaired using the HPFRCC: two repair heights (300 and 500 mm) and two repairing processes (with and without axial loads). The effectiveness of the repairing schemes was evaluated by comparing load-carrying capacities, displacement ductility, stiffness, and energy dissipation of the columns. The results indicated that the load-carrying capacity and ductility of the repaired columns could be respectively 14% and 29% higher than those of the original columns. With axial loads during repairing, the repaired columns displayed better cyclic performance. Increasing the repair height beyond the plastic hinge zone slightly improved the load-carrying capacity and ductility. Considering the performance-to-cost ratio, it is recommended that the repair height of HPFRCC be 1.5 times the depth or width of the damaged column.