Bond-anchorage Capability Experimental Research On 600MPa Hot-ribbed Steel Bar

600MPa hot-ribbed steel bar is a new kind steel bar,which has lots of advantages,such as high strength,much safety stock,and savings more reinforcement steel in engineering.Research and application of 600 MPa steel bar not only has a very important significance to China's energy-saving and emission reduction,but also deeply change in using steel bar level.However,600 MPa steel research has still not started in our country.A pull-out experiment of 63 specimens was carried out in this paper,so that the bond-anchoring property was discussed deeply.Based on the experiment,a systemic study was finished.The systemic study included bonding mechanism,main influencing factors of bonding property,the development length of steel bars,?-s constitutive relationship and reliability analysis.The details are as follows:63 specimens were being pulled out in this experiment,and the main factors which influenced bond-anchoring property of 600 MPa steel bar were analyzed.The main influenced factors were concrete strength,cover thickness of concrete,development length of steel bars and ratio of transverse stirrup.Research shows that increasing the strength of concrete and the cover thickness of concrete can improve the ultimate bonding strength.The longer development length of steel bar has,the weaker of average bonding strength is.Compared with common specimens,specimens placing transverse stirrup have good ductility.Based on 63 prism testing data,a ultimate bonding strength formula is carried out.According method of inner-embedded strain-gauge in this paper,distribution of bond stress was discussed about different development length,and the formula was obtained.Basic bond-slip function was suggested by analyzing bond stress and the relative slip disciplinarian along the anchoring length.The product form between basic bond-slip and bond stress position function was used to study ?-s constitutive relationship.Finally,?-s constitutive relationship applying to 600 MPa hot-rolled ribbed bar was proposed.Center point method was used to analyze reliability,and advised the development length of 600 MPa hot-ribbed bar.Results of the study show that the bond-anchoraging length of 600 MPa steel bar can still be designed by code for designof concrete structures(GB50010-2010).