Bond behavior of plain round bar embedded in high ductile concrete under monotonic and cyclic loading

Bond behavior is the basis of combined action of steel bar and high ductile concrete (HDC), which has an important effect on the mechanical performance of reinforced HDC structures. In this paper, nine groups of pullout specimens were tested to investigate the bond behavior and degradation mechanism of plain round bar embedded in HDC under monotonic and cyclic loading. The design parameters included HDC compressive strength, HDC flexural toughness and anchorage length. Experimental results indicated that only a small free end slip occurred for specimens with plain round bar when the maximum bond stress was reached. Bond strength of polyethylene fiber specimens was 1.67 times that of polyvinyl alcohol fiber specimens. Compared with the monotonic specimens, the cyclic specimens exhibited an obvious degradation in bond strength and residual bond strength, and the degradation degree of former was more serious than that of latter. Besides, it also should be noted that the HDC compressive strength had a great influence on the energy dissipation capacity of cyclic specimens. Based on the test results, a calculating formula of bond strength was built. Then this paper proposed a bond stress-slip relationship model for the plain round bar embedded in HDC under monotonic loading.