Causes of elongation in reinforced concrete beam subjected to cyclic loading
Elongation in the plastic hinge regions of reinforced concrete beam has a significant influence on the integrity of the structure. This paper describes the research carried out to examine the key mechanisms that contribute to the elongation in plastic hinges. The effect of axial forces on the mechanisms that causes elongation is also investigated. A finite element program is employed to simulate the experimental work reported in literature. The analytical predictions are compared with the experimental results. It is found that elongation in plastic hinges is associated with two key factors: (1) unrecoverable stretching of compression reinforcement, and (2) plastic strains in reinforcement due to plastic rotation. The contributions of these factors to elongation are found to be markedly different for different types of plastic hinge.