Experimental Research For The Seismic Behavior Of Exterior Joint With HRB500 Steel

The 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 HRB500 reinforcement has been completed.Many large-scale steel factory in china have ability to manufature this steel. during the state's 863 plan. In order to incorporated it into the standard of engineering construction as soon as possible, loading mechanism and seismic performance of different type of specimens reinforced with HRB500 steel is needed to verify.A series of tests are conducted focusing on the seismic behaviour of joints with HRB500 reinforcement in our research group and the test about exterior join in the paper is one part of this.6 full-scale tests for beam-column combination of exterior joint with HRB500 reinforcing bar have been conducted. In specimen the longitudinal bars are anchored with 90ostandard hook and the inner diameter of hook is 5db. The seismic behavior of beam-column joints different from shear-compression ratio, stirrup parameter, relative anchorage length ldhE/db, strength of stirrup are analyzed, and the major conclusions are summarized as follows:①. The comprehensive seismic performance of exterior joint reinforced with HRB500 steel under low cyclic reversed loads: The crack width, the deflection in the beam end, the shear deformation in the joint zone and the slip of longitudinal steel become large. Displacement ductile coefficient of the combination declines on the condition of sustaining the basic shear capacity;②. In order to give full play to its advantages of HRB500 steel on the basis of ensuring that the structure has good seismic performance, the paper suggests that when the steel strength is improved, the concrete strength should be improved to correspond;③. In Chinese current construction code, the inner diameter value of longitudinal steel hook anchored in exterior joint is not enough;④. The design value of stirrup strength should be lowered when HRB500 steel is applied for stirrup;⑤. Improving axial-compression ratio appropriately when that is not too big is favorite to bond anchorage.