1.Tongji university;2.China Construction Fifth Engineering Division Corp.,ltd
Thirty-two pullout tests were carried out in order to investigate the bond behavior between upsetting steel bar and high strength steel fiber reinforced concrete (SFRC). Two types of steel rebar (upsetting and normal steel bar), six types of bond length (3d-6d for upsetting steel bar, 5d-8d for normal steel bar, d is the diameter of steel bar) and two types of concrete coverage thickness (2d and 4d) were considered in this study. Bond-slip relationship, failure pattern, bond strength and the corresponding slip were analyzed.It was found that the upsetting steel bar can effectively enhance the bond strength between steel bar and SFRC, significantly reduce the relative slip corresponding to the bond strength. The failure pattern was changed from concrete splitting failure to steel bar tensile failure. In addition, based on the experimental data, the empirical bond stress-slip relationship between normal/upsetting steel bar and SFRC was established and the recommended correction coefficients of anchorage length were proposed.