Research On Dynamic Behavior Of Joints Of RC Frame Structure With NES

Structural passive control is widely used in various types of building structures,because it does not need external energy supply and its control effect is obvious.Nonlinear Energy Sink(NES)can effectively absorb seismic energy to achieve the effect of shock absorption and reduce the seismic response of the structure.The joint of reinforced concrete frame structure is the key part of the structure,which has a great influence on the seismic performance of the structure.Therefore,it is of great theoretical significance and engineering application value to study the dynamic characteristics of beam-column joints of reinforced concrete frame structures with NES under earthquake.The main contents were as follows:(1)A RC frame structure model with a scale ratio of 1:4 was designed according to the similarity ratio of seismic uniform simulation,the material performance test was carried out and the construction of the model was completed.A NES damper was designed,and the test of white noise was tested,and the natural frequency range of the device was measured.(2)The NES damper was installed on a five-storey reinforced concrete frame model and shaking table test was carried out,the effect of costing-energy on reinforced concrete frame structure is studied.With the increase of earthquake intensity,the natural frequency of structure decreases gradually.The natural frequency of RC frame structure with NES damper decreases faster than that of ordinary frame structure,which indicates that NES damper can effectively improve the seismic capacity of RC frame structure.NES damper can effectively reduce the strain of beam-column longitudinal reinforcement and stirrups at reinforced concrete joints,consequently lead to plastic hinge failure at the end of beams and shear failure in joints,and achieve the design objectives of "strong column and weak beam" and "strong joints and weak members" of frame structures,and effectively protect joints.The asymmetric distribution of tension and compression strain of concrete at joints is mainly manifested by pressure,which proves that it exists a "diagonal compression bar mechanism" for concrete at joints.(3)The NES damper was arranged at different storey heights to investigate the influence of the height of the damper on the dynamic performance of structural joints.Under the same seismic wave,the horizontal seismic shear of RC frame joints with NES shock damper is reduced.The higher the storey height of shock damper is,the better the shock absorption effect is.(4)According to the parameters of the test model,the control effect of the NES damper on the joint under the test condition was simulated by using ABAQUS finite element simulation software.By analyzing the results of shaking table test and software simulation,they can draw the same conclusion:In the case of small earthquake magnitude,the simulation of ABAQUS software is in good agreement with the actual test results,and the finite element analysis has certain accuracy.With the increase of earthquake magnitude,the damage of the structure is aggravated continuously,and the structure is in the plastic stage.The strain simulation at the joint will deviate from the real test results.