Cyclic over loads on life of bond anchorages in reinforced concrete

Performance of anchorage reinforcement under dynamic loads is important to ensure adequate safety and structural integrity with adequate ductility. In the end regions, load transfer mechanism is influenced by cyclic loads under overloads. Since anchorage bond and its mechanics under cyclic over loading are absent, an experimental study to investigate the influence of type of loading and lateral confinement have been performed. Anchorage bond in concrete with different lateral confinement by spiral reinforcement has been studied under cyclic loading. The bond length was 80mm in the middle of 150mm depth of concrete. Bar diameter of 25mm was embedded in 25 MPa strength concrete with spirals of 8mm diameter with pitch of 25mm, 50mm and 75mm was adopted. It has been observed that the strength of concrete and the level of lateral confinement showed significant influence on the mode of failure and bond stress. Pullout failure was observed under monotonic and cyclic loading under overload in confined concrete. Different failure modes have been observed depending on the influencing parameters. The life of reinforced concrete due to deterioration of anchorage bond in rebars under cyclic loading is significantly reduced by the accidental overloads. The early application of overloads lowers the bond strength and service life of reinforced concrete. Abhishek, P, Harekrishna Kumar, and G. Appa Rao