EXPERIMENTAL STUDY ON BOND BEHAVIOR BETWEEN HIGH DUCTILE CONCRETE AND RIBBED STEEL BAR

In order to study the bond performance between high ductility concrete (HDC) and ribbed bars, 20 groups of specimens were designed and manufactured. Through the center pull-out test, the failure mode and bond-slip failure mechanism of specimens under monotonic and repeated loads were studied, and the effects of compressive strength, of fiber content, of fiber types and of protective layer thickness of HDC on the bond performance between ribbed steel bars and HDC were analyzed. The experimental results show that: under monotonic and repeated loads, brittle splitting failure occurs in ordinary concrete specimens, and splitting and pulling-out failure occurs in HDC specimens. The test results also show that the bond strength between ribbed steel bars and HDC increases with the increase of HDC compressive strength. When the compressive strength of HDC is the same, the increase of fiber content can improve the bonding performance between ribbed steel bars and HDC. Compared with PP fiber, PE fiber and PVA fiber with the same volume content can effectively limit the development of radial cracks in concrete and improve the bond strength between ribbed steel bars and HDC. According to the failure mode and bond strength, the critical relative protective layer thickness is 2.0. Under monotonic and repeated loads, the bond strength ratio of specimens is dominated by fiber types and relative protective layer thickness, while the residual bond strength ratio is dominated by compressive strength and fiber content. According to the test results, the bond strength calculation formula and bond-slip constitutive model between ribbed bars and HDC are established.