New avenue of achieving ductility for reinforced concrete members

The flexural deformation of structural members is due to their curvature. For reinforced concrete (RC) members, this curvature depends on the tensile strain of the reinforcement and the compressive strain of the concrete. As concrete is a brittle material with little ductility, RC members achieve ductility and adequate deformation capacity mainly through the tensile straining or yielding of the reinforcement. When the tensile straining of the reinforcement is limited, such as in the case of over-reinforced RC beams and RC columns with large axial loads, whereby the tensile reinforcement does not yield and the member fails due to concrete crushing, the ductility of the member is limited. The application of high-strength steel or fiber reinforced polymer reinforcement significantly reduces the ductility of the tensile reinforcement, which results in a substantial reduction in the ductility of the structural member. Existing methods for improving the ductility of concrete structures with nonductile reinforcement are not satisfactory. A new scheme of providing ductility to RC members through compressive yielding instead of tensile yielding is developed and introduced in this paper. The effectiveness of the new scheme is illustrated by experimental testing of RC beams. The successful application of this novel technique may pave the way for a new field of research and application of concrete structures.