Eddy Current Damping-rack And Gear Wall And Numerical Simulations On Its Seismic Mitigation Performance

The technology of structural vibration control has been developed for more than40 years.Various types of damping devices have been developed,all of which have their own advantages and limitations.The damping wall,whose seismic mitigation effect is excellent,was first proposed by Japanese scholars and has been widely applied.The material of viscous liquids is often used to dissipate energy in the damping wall,but there are shortcomings such as loss of seals,liquid leakage,and slow start-up,whose mechanical property is also closely related to the working temperature.However,eddy current damping has the advantages of non-contact,no working fluid,sensitive starting,and low temperature influence.It is expected to improve the mechanical property of the damping wall.The rack and gear are common motion amplification devices,which are cost-effective and can effectively improve the the efficiency of energy dissipation of eddy current damping.In this study,the eddy current damping and rack with gear were applied to the damping wall,and a new type of damping device,called eddy current damping-rack and gear wall（ECD-RGW）,was proposed.The mechanical performance of the ECD-RGW was studied by theoretical analysis,test and electromagnetic finite element simulation,and the seismic mitigation effect of the structure attached with ECD-RGW was investigated.The main contents and results of this thesis are as follows:（1）A damping device called ECD-RGW was firstly proposed.The test of the amplification effect of the eddy current damping-rack and gear was completed on the large-scale test platform for eddy current dampers of Hunan University,whose results were compared with the results of electromagnetic finite element simulation.The results show that the measured results are in good agreement with the results obtained from electromagnetic finite element simulation,and the ECD-RGW shows excellent energy dissipation capacity.（2）The mechanical property of ECD-RGW was studied by using COMSOL Multiphysics,and the influence of the design parameters on the mechanical property was systematically studied.The results show that the efficiency of energy consumption of ECD-RGW can be significantly improved by reducing the air gap,installing the back iron of the conductive plate and increasing the number of permanent magnets;the thickness and the material of the conductive plate have a significant effect on the critical velocity and peak damping force of ECD-RGW.（3）The time-history analysis of the structure attached with ECD-RGW,which was under earthquake excitations,was carried out.Compared with the fluid viscous damper,the seismic performance of the ECD-RGW was investigated based on the single degree of freedom system.The results show that the ECD-RGW can achieve the same seismic mitigation effect as the fluid viscous damper,which can replace fluid viscous damper as a new type of damper with better mechanical performance.（4）Based on the second Benchmark problem of the seismic structure,the seismic performance of a 20-story steel frame structure attached with ECD-RGW was studied.The influence of earthquake intensity on the seismic performance was discussed,and the arrangement of the ECD-RGW on structural floor was optimized.The results show that the ECD-RGW can drastically reduce the seismic response of the structure,which shows good energy dissipation capability and self-protection capability.The position of the ECD-RGW has a significant impact on seismic performance.For the 20-story steel frame structure,it should be arranged continuously and evenly on the middle and upper floors.The seismic mitigation performance of the structure increases with the increase of earthquake intensity,and it increases first and then decreases with the increasing of the number of the ECD-RGW.Reasonable setting of the number of ECDRGW can effectively improve the seismic mitigation performance of the structure.