| The range of non-prestressed reinforcement strength widely used in reinforced concrete structures in China currently is 300～400MPa,which is lower than that of developed countries 1～2 grade. In order to conserve resources, realize the sustainable economic development and consistent with the international practice as soon as possible, China urgently needs to promote application of higher strength steel. At present, the development of 500MPa reinforcement has been completed during the state's 863 plan. Many large-scale steel factory in China have ability to manufacture this steel. In order to incorporate it into the standard of engineering construction as soon as possible, loading mechanism and seismic performance of different type of specimens reinforced with 500 MPa steel is needed to verify.Results from five full-scale interior beam-column joint specimens which beam's and column's longitudinal reinforcing bar is 500MPa are presented in this thesis. These joint specimens are designed according to Code for Design of Concrete Structures (GB50010-2002) and tested under reversed cyclic loading. The objects of the experiments were to study the seismic performance of the joints with high-strength steel designed according to code that is carried out nowadays, comparing with seven interior beam-column joints with 500MPa reinforcing bar and a series of interior beam-column joints with ordinary-strength reinforcing bar those were carried out by the author's group, the law of the bond deterioration of beam bars through the joints and hysteretic dissipated energy of joints are studied. The details concerned and corresponding main results are as following:①A series of interior beam-column joint specimens with 500MPa reinforcing bar,hc d = 20 These joint specimens work with high axial load ratio and high shear-compression ratio.The relation of displacement ductility factor3 <ΔΔy< 4 when specimens failed, observed worse seismic performance, but the story drift when specimens failed were between 0.04~0.05, obversly bigger than specimens with ordinary-strength reinforcing bar.②According to the analysis of tests data, specimens which the relative length of beam bars crossing joint hc d = 20 that is the restrictive condition of code, bond performance of specimens is worse, And compared to the relative length of beam bars crossing joint hc d = 25, Under the same shear-compression conditions, the damage of joint's concrete is more serious, the process of diagonal crushing is more quick, hysteretic dissipated energy is worse.③Because of the yield strain of 500MPa is much bigger than that of ordinary-strength reinforcing bar. So the yield displacement of specimens is bigeer, the displacement ductility factor of assemblage is smaller.④With the tests of 12 interior beam-column joint specimens with 500MPa reinforcing bar and 21 interior beam-column joint specimens with ordinary-strength reinforcing bar that have been completed by author's research team, the law of bond deterioration of beam bars crossing the joints,which is influenced by reinforced bar strength,concrete strength,shear-compression ratio and the relative length of beam bars crossing the joint,is analyzed. The propositional formula of the relative length of beam bars crossing joint hc/d, which is influenced by reinforcement strength,concrete strength and shear-compression ratio, is presented.
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