Of Hrb500 Bond Properties Of Bars The Pilot Study

HRB500 steel bar is a kind of hot-ribbed bar whose characteristic tesile strength is 500MPa. It is a new sort of steel with high strength and good ductility, and it was exploited through alloying drops of other special metals with steel in China.In this paper, we carried out the research about the mechanical capability, especially the bond-anchorage property in concrete of HRB500 steel bar to solve the problem on the anchorage design of HRB500 steel bar in concrete structures.The mechanical capability test proves that the stength and the elongation of HRB500 steel bar not only satisfy the requirements in Chinese standard, but also achieve the demands in Eurocode. So it can be used in seismic design structures. And in the design of concrete structure, the value of characteristic tensile yield strength fyk can be set as 500MPa, the value of modulus of elasticity Es can be set as2.1x105N/mm2.According to 72 pullout tests, the effects of concrete strength, thickness of concrete cover, anchorage length, and stirrup ratio etc. for the bond-anchorage property have been analysed. By way of experimental statistical regression, the calculating formula of ultimate bond-anchoring strength has been established. The result is in good agreement with what comes from the formula of crescent hot-ribbed bar proposed by the special bond-anchorage research group of Chinese "code for design of concrete structures'.Based on the above experiments and present τ-s constitutive relationships, the bond-anchorage τ-s constitutive relationship for HRB500 steel bar has been established.The design of anchoring length through reliability analysis has been proposed. The result shows that the anchoring length for HRB500 steel bar can be designed by the formula in existing "code for design of concrete structures"(GB50010-2002).