Influence of matrix ductility on tension-stiffening behavior of steel reinforced engineered cementitious composites (ECC)

This paper investigates the interaction of structural steel reinforcement and high-performance fiber-reinforced cement composites (HPFRCC) in uniaxial tension. The effects of cementitious composite ductility on the steel reinforced composite deformation behavior are experimentally investigated and contrasted to conventional reinforced concrete. The substitution of brittle concrete with an engineered cementitious composite (ECC), which represents one particular type of HPFRCC with strain hardening and multiple cracking properties, has shown to provide improved load-deformation characteristics in terms of reinforced composite tensile strength, deformation mode, and energy absorption. Analysis of the deformation mechanisms suggests that the combination of steel reinforcement and ECC results in composite action, where unlike in reinforced concrete or conventional fiber-reinforced concrete (FRC), both constituent materials deform compatibly in the postcracking and postyielding deformation process. This deformation compatibility results in a more uniform strain distribution in reinforcement and composite matrix, reduced interfacial bond stress, and controlled damage at relatively large inelastic composite deformations. Research described in this paper particularly focuses on the influence of composite ductility on the deformation behavior of the reinforced composite and its effects on the strain distribution in the reinforcement, composite matrix, and interfacial bond.