Bond behavior of deformed bar embedded in Engineered Cementitious Composites under cyclic loading

Abstract

The bond behavior between deformed bar and ECC has a significant effect on the mechanical performance of reinforced ECC structures when subjected to dynamic loading. In this paper, 12 groups of ECC specimens and one group of concrete specimen as control were prepared to investigate the bond behavior of deformed bar under cyclic loading. Designed parameters included compressive strength, flexural toughness, cover thickness and anchorage length. Experimental results showed that, owing to the fiber bridging effect preventing the opening and propagation of internal cracks, failure modes of ECC specimens demonstrated an obvious ductility whereas the brittle splitting failure occurred for concrete specimen. The bond strength of steel bar in ECC had an extreme enhancement as the compressive strength of matrix increased. In comparison with the monotonic specimen, the cyclic specimen undergoes an obvious degradation in terms of bond strength as well as stiffness, and the degradation coefficient of bond strength ranged from 0.6 to 0.9. It was noticed that the increase in compressive strength and cover thickness can reduce the degradation degree of bond strength. Furthermore, the energy dissipation capacity of cyclic specimens rose first and then fell since the toughness of matrix increased. Finally, a calculating equation of bond strength under cyclic loading was proposed and the predicted results had a great agreement with the test results.