NONLINEAR FE MODELLING OF ANCHORAGE BOND IN REINFORCED CONCRETE

Abstract

The transfer of forces from the surrounding concrete to the reinforcing bars in reinforced concrete (RC) can be influenced by several parameters. In this paper an attempt has been made to study the influence of specimen geometry, bar diameter, strength of concrete, lateral confinement and embedment length on the bond properties of concrete. The embedment length of the bar was varied between 50mm and 400mm by varying the diameter of the bar, strength of concrete and lateral confinement. The different bar diameters of 16, 20 and 25mm were selected along with three different concrete strengths of 25, 40 and 65MPa. The specimens with the above parameters were modeled by using a nonlinear finite element analysis package. It has been found that for the same geometry, the specimens with small bond length exhibited high bond strength. With the range of bar diameters considered the bond strength of concrete decreases as the diameter of the bar increases. The splitting failure has been observed in unconfined concrete, while the pullout failure was predominant when the concrete laterally confined. In case of large embedment length, the post peak plateau is prolonged with small diameter bars when compared to the large diameter bars. The descending branch of the bond stress-slip response with large diameter bars has been found to be steep.