Experimental Research Of The Interior Joint With HRB500 Steel In Earthquake-resistant Frames

Based on the reversed cyclic loading six tests of the interior joints of framework, which are designed according to Code for Design of Concrete Structures (GB50010-2002) and in which are with 500MPa bar as longitudinal bars of beams and columns, high bond condition and one is with large axial load ratio and large shear-compression ratio, the seismic performance of the assemblages were main studied that is influenced by high-strength of bars according to the current Design Code. With the reversed cyclic loading tests of several interior joints with HRB335 and HRB400 bars as longitudinal bars of beams and columns in reinforced concrete plane frames which have been completed by our study group,the law of bond deterioration of beam bars crossing the joint is analyzed and dissipated energy capacity of joint, the seismic behaviour of the interior joints has been contrasted roundly. The specific work and main conclusions we concerned are as following:â‘ One plane frame joint specimen with rectangular column, which is with large axial load ratio and large shear-compression ratio which is upper limit defined in the code has been completed, and the displacement ductility of the specimen is 3 in shear failure, the seismic performance of joints can not be accepted.â‘¡According to the analysis of tests data, in the same condition, the penetrating length is lengthened to 25 times of bars diameter, the seismic performance of joints can be improved.The shear-compression ratio of joint is larger, then the damage of joint is slighter, the speed of bond deterioration of beam bars crossing the joint is slower, dissipated energy capacity of joint is larger.â‘¢The yield displacement of specimens is lager, the ductility capacity of the specimen is worse ,but . the displacement of the specimen is large.â‘£The reversed cyclic loading tests of the interior joints of framework which are with 500MPa bar as stirrup of joints also have been finished, according to the analysis of tests data, we can conclude that when the joints were damaged, few of the stirrup of joints has yield, the shear behaviour of them has not been utilizized.