Development of arching action in longitudinally-restrained reinforced concrete beams

Membrane action of reinforced concrete (RC) beams is one of the primary mechanisms that enhances progressive collapse resistance of frames and influences the robustness of a structure under an unforeseen overload event. Compressive membrane action increases both the capacity and stiffness of longitudinally-restrained reinforced concrete members. In this study, six scaled reinforced concrete beam assemblages with longitudinal end restraints were tested under a monotonically increasing displacement applied at the mid-span. The longitudinal reinforcement ratio and configuration of stirrups were the main variables investigated in the experimental programme. The effect of support stiffness and strain penetration on arching behaviour is studied using a numerical model calibrated against the experimentally measured rotation of the end supports. It is concluded that, for RC beams, the longitudinal reinforcing ratio and stirrup configuration has only a minor influence on arching action, whereas compressive strength of the concrete and strain penetration have pronounced effects on the peak as well as post-peak response.