Research And Application Of Eddy Current Tuned Mass Damper

With the continuous development of China’s economy and the continuous promotion of urbanization,the span of footbridge is also inclined to the development of large span,but the increase of span will bring a new problem,that is,it will reduce its natural frequency,make it easy to resonate under the action of pedestrian load,so that pedestrians feel uncomfortable,It is a scientific and economical technology to reduce vibration by using TMD(tuned mass damper).As the damping part of TMD,eddy current damper has a good engineering application prospect.In this paper,the damping characteristics of the eddy current damper are studied from both theoretical and simulation aspects,and the theoretical formula for the parameter design of the tuned mass damper is derived.Finally,the parameters of the tuned mass damper are selected from the economic point of view combined with the actual project,and an eddy current damper is designed based on the selected damping parameters.The main contents of this paper are as follows:(1)Based on the molecular current model and the equivalent magnetic charge model,this paper deduces the formula of the magnetic field distribution generated by the cuboid permanent magnet,the current distribution generated by the movement of the finite large conductor plate in the magnetic field and the eddy current resistance force.The COMSOL simulation results are compared with the theoretical calculation results and the existing simulation results,To verify the feasibility of COMSOL simulation.(2)In this paper,the eddy current resistance force of an eddy current damper is simulated and analyzed under the influence of different magnet size,magnet spacing,copper block size,copper block spacing,magnet base size and copper block installation horizontal and vertical plate size.(3)In this paper,the PQ fixed-point theory and optimal parameter design formula of two degree of freedom system with tuned mass damper are derived,and the relationship between dynamic amplification factor and different frequency ratio,mass ratio and damping ratio is analyzed respectively when the main structure has damping or not.The finite element analysis software MIDAS civil is used to establish the element model of pedestrian bridge.Based on the pedestrian load model in German pedestrian bridge design guide EN03 and building vibration load standard,the dynamic response of pedestrian bridge is analyzed and evaluated with reference to EN03 comfort evaluation standard,and the vibration reduction measures are analyzed.In order to reduce the vibration,the tuned mass damper(TMD)is installed to control the vibration.The parameter design of TMD is carried out according to the optimal parameter design formula,and the relationship between the vibration reduction rate and the installation position,stiffness,mass,damping coefficient and number of TMD is analyzed,Based on the economic considerations,the parameters of the optimal tuned mass damper are selected.Finally,the eddy current damper is designed based on the optimal damping coefficient parameters.