Experimental Study On Shear Behavior And Seismic Retrofit Of SRC Column-RC Beam Joints

Recently, steel reinforced concrete(SRC) structures are widely adopted in tall buildings. SRC structure is provided both advantages of steel and concrete when properly designed. However, there is few information of the seismic behavior and design method of SRC joints, for its complicated stress behavior and resistant mechanism.In order to implement the performance-based seismic design for SRC beam-RC column joints, the following studies are carried out: (1)Two SRC column-RC beam assemblages with weak joints and two damaged SRC column-RC beam assemblages which were retrofitted with steel plate hoop in joint core are tested under cyclic loading. The influence of the strength ratio of joint to beam on the seismic performance and hysteretic behavior of subassemblages, and the effects of joints retrofitted by steel plate hoop are studied;(2) The shear mechanisms of SRC joints and seismic design method are studied;(3)The restoring force model for shear force-shear deformation in SRC joints is studied.Based on experimental study and theoretical research, the following can be concluded:(1) It is indicated that SRC joints have better seismic behavior, for the resistant effect of the steel web in joint core.(2)The strength ratio of joint to beam is one of the most important factors to control the failure pattern of assemblages. When the value of ratio is less than 1.1, assemblages tend to be shear failure in joint core.(3) Joints core shear deformation and bond-slip of longitudinal bar in joint core caused an large proportion in displacement of SRC with weak joints, and it is necessary to take these two disadvantage deformation into account in seismic design and earthquake response analysis.(4)It is indicated that joints retrofitted by steel plate hoop showed satisfactory seismic performance.(5)The proposed design shear force formula for calculation which is based on joint shear deformation can be used to design the joint core for different performance.(6) The elastic-plastic behavior of SRC joint can be simulated reasonably with the proposed restoring force model.The study results can be a valuable guide for the elastic-plastic analysis when the shear deformation of joints needed to be considered.