Experimental Study on Bond-slip Behavior of Rebar Anchored in Concrete

Bond-slip behavior of rebar in concrete is crucial to the dynamic behavior of reinforced concrete structures due to the reduced stiffness at column ends and beam-column connections. This study conducted a series of 99 pull-out tests of rebar anchored in concrete to investigate the bond-slip behavior with different parameters. A novel test setup for the pull-out test of rebar was designed. The test setup can reduce loading misalignment, local confinement, and rotation-induced measurement errors. Four groups of pull-out tests with different concrete strengths, rebar diameters and anchorage lengths were conducted. The failure modes of different specimen groups were analyzed, including concrete cone failure, splitting-pullout failure, cracking failure and splitting failure. The bond strength for each group of specimens were also determined. By comparing with the widely-accepted formula for the bond strength, the real bond strength was found to be significantly underestimated due to the neglection of the important influences of rebar diameter and anchorage aspect ratio. It is hoped that the novel test setup and the results from the pull-out tests could serve as a useful reference to further investigations of a more comprehensive rebar bond-slip behavior.