Experimental And Analytical Study On Seismic Behavior Of Rubber Concrete Frame Joints

The common reinforced concrete frame joints have complex mechanical state,poor ductility and low energy dissipation capacity.The research shows that the concrete doped with waste rubber particles has the advantages of light weight,high energy dissipation,good ductility,vibration and noise resistance.This paper holds that the application of these advantages of rubber concrete to frame joints can not only reduce the environmental pollution caused by waste rubber,but also provide theoretical basis and scientific support for the practical application of rubber concrete frame joints.In this paper,three full-scale rubber concrete frame joints and one full-scale ordinary concrete frame joints with equal strength are fabricated.Through quasi-static test,the seismic behavior of joints,such as failure mode,hysteretic behavior,displacement ductility and energy dissipation capacityand so on are studied.The degradation law of longitudinal bond stress,shear deformation and stirrup strain in the core area of joints are discussed.The main research results show that:The failure process of rubber concrete frame joints is similar to that of ordinary concrete,and all of them go through four stages: initial crack stage,through crack stage,limit stage and failure stage.The failure form of the joint is mainly shear failure.Under the same strength,the cracking resistance of rubber concrete frame joints is obviously stronger than that of ordinary concrete,and the integrity of rubber concrete frame joints is better in the whole loading process.The toughness of rubber concrete frame joints is generally stronger than that of ordinary concrete when the bearing capacity of rubber concrete frame joints decreases to the failure stage.After the ultimate load,the energy consumption capacity of rubber concrete frame joints is about 10% higher than that of ordinary concrete.Bond stress of beam tendons in rubber concrete frame joints The bond strength is lower than that of ordinary concrete frame joints,which is about 5% lower than that of ordinary concrete frame joints.With the increase of axial pressure,the shear capacity,energy dissipationcapacity,cracking resistance and bond stress of rubber concrete frame joints increase correspondingly,but the ductility of rubber concrete frame joints decreases.In addition,excessive axial pressure increases the decline rate of load-bearing capacity of specimens before failure,and the damage is the most serious.Based on the experimental data,the calculation formula of shear capacity of rubber concrete is theoretically analyzed by comparing the measured shear value with the theoretical value.The finite element software ABAQUS is used to analyze the test specimens nonlinearly,and the hysteretic curves of the joints,the tensile damage of concrete,the compressive damage and the stress nephogram of the reinforced skeleton are obtained.The analysis results show that the experimental values are in good agreement with the theoretical values,which shows that ABAQUS can simulate the mechanical behavior of rubber concrete frame joints better.On this basis,the strength grade,axial compression ratio and stirrup diameter of rubber concrete are analyzed by finite element method,and its effect on the mechanical properties of rubber concrete frame joints is understood.