Shear strengthening of RC beams with corrosion-damaged stirrups using FRP grid-reinforced ECC matrix composites

Abstract

This paper presents an experimental investigation of the shear behavior of reinforced concrete (RC) beams with corrosion-damaged stirrups strengthened using a fiber-reinforced polymer (FRP) grid-reinforced engineered cementitious composite (ECC) matrix. A total of 18 beam specimens, including four referential beams and 14 strengthened beams, were prepared and tested. After corroding the stirrups to the expected ratio using the electrochemically accelerated method, the lateral corrosion-damaged concrete cover was removed, and then repaired using the FRP grid-reinforced ECC matrix (FGREM). The main test parameters included the stirrup corrosion level, shear-span ratios, and types and strengthening amounts of the FRP grid. Based on the experimental results, the shear bearing capacity of the beams with corrosion-damaged stirrups improved significantly after being restored using this technique. The embedded FRP grid could effectively share the shear force borne by the stirrups and the ECC improves the deformation characteristics and energy absorption of the specimen owing to its excellent strain-hardening behavior. Furthermore, a theoretical calculation formula was proposed to predict the shear bearing capacity of the strengthened beams based on the truss-arch model, which was confirmed to be safe and accurate after being assessed using the modified version of the demerit points classification (DPC) method.