Shear strengthening of reinforced concrete beams with high strength strain-hardening cementitious composites (HS-SHCC)

Strain-hardening cementitious composite (SHCC) was widely recognized as a material that possesses great potential in the repair and strengthening of reinforced concrete (RC) structures. SHCC can usually achieve high ductility with multiple cracking behavior and it also has excellent durability. Moreover, high tensile strength can also be achieved with proper mix design. In this study, conventional RC beams with shear span-to-depth ratio of 1.5:1 and 2.5:1 were cast first, while high-strength SHCC were then cast as thin patches on lateral surfaces of the RC beams to serve as the strengthening layers. The beams were subject to four-point bending test to obtain their ultimate shear capacities. It was observed from the test results that the ultimate shear capacity of strengthened RC beams increases evidently compared to the reference beams. Upon ultimate shear failure, no spalling of surface concrete occurred as it was restrained by the strengthening layers with the formation of stable multiple fine cracks. A finite element model was constructed to simulate the experimental tests. The results of FEM analysis correlated well with experimental results. A numerical parametric study was then carried out to evaluate the influence of the thickness of HS-SHCC layer and the shear span-to-depth ratio. This study concludes the feasibility of the use of high strength SHCC in shear strengthening of RC structures.