Preliminary Study On Permanent-magnetic-levitation-based Vertical Isolation For Cultural Relics

Most cultural relics are not anchored to their bases.This type of placement made the relics very fragile and ease to slide rock and overturn.Nowadays,there are already plenty researches and applications on lateral isolations.However,there are not many effective methods for the vertical earthquakes.Many cultural relics are equally fragile to vertical seismic action,thus it is imperative to protect consider the adverse influences caused by vertical ground motions.Based on the systematic reading and summary of a large number of related literatures,permanent magnets are used to fulfill vertical isolation in this paper and mechanical properties of permanent magnets are carefully researched.The following work is finished.1.Determination of permanent magnet constitutive relations.Parameters which affect the magnetic forces are studied.A more precise fitting formula of magnetic force is presented.The accuracy of the formula is calibrated using static tests and finite element analyses.The work supplies the theoretical basis for optimal of magnetic based isolation and practical applications.2.Magnetic vertical isolation device is designed and dynamic tests are conducted.4 magnetic vertical isolation devices with different parameters is designed.The frequency and damping ratio are tested through free vibration.Shake table tests are conducted to test the damping effectiveness.Factors like friction,magnetic forces and isolated mass are researched.Tests results under different schemes are presented.This work offers preliminary results for magnetic vertical isolation and provides calibration results for further simulation.3.The design parameters of magnetic vertical isolation device are given,and the reliability of the numerical simulation method is verified by comparing with the shaking table test results.LS DYNA is used to build the models.Results acquired from tests are used to calibrate the FE models,the influence of ground motion spectra characteristics,PGA,initial equilibrium positon,isolation mass,damping factors are studied.