Analytical modeling of the pre- and post-yield behaviour of bond in reinforced concrete

This paper presents the theoretical basis and the main results of an analytical model that describes the pre– and post–yield response of bond in reinforced concrete, as well as its influence on the behavior of structural members. The model is based on a number of reasonable assumptions that simplify the differential equation governing the phenomenon. In this way, a closed–form integration is feasible in certain cases, and relatively simple but accurate expressions can be worked out for the interface slip, the strain and the stress in the reinforcement and the bond stress at the bar–concrete interface. Applications are made to different structural members (pull–out specimens, tension ties and beams in bending), whose behavior is well documented in the literature. The agreement between the available test data turns out to be quite satisfactory. Consequently, the proposed model can be usefully adopted for studying the serviceability behavior, the ductility and the post–yield response of a variety of reinforced–concrete members.