Theoretical And Experimental Study On Modular Metal Seismic Isolation Bearing

China is an earthquake-prone country.Tall-flexible electrical equipment and freestanding cultural relics are often seriously damaged in earthquakes.Considering the importance of electrical equipment and the preciousness of cultural relics,it is very urgent to reduce their damage under earthquakes.In recent years,domestic and foreign researchers have carried out a series of studies on the applicability of isolation technology for electrical equipment and freestanding cultural relics.However,the anti-overturning capacity,self-centering ability and university of seismic isolation bearings are still insufficient.In this paper,the modular metal seismic isolation bearing(MMSIB)and its design method was proposed.Taking current transformer and freestanding vase as examples,the reliability of seismic isolation device and the feasibility of design method were verified using shaking table tests.Considering different design objectives,the recommended design parameters of MMSIB are given.The main research work and innovation achievements include the following four aspects:1.The strucucture and design method of MMSIB were proposed.The MMSIB is composed of linear guide rail,slider,spring,friction damper and other parts.The number of guide rails in each layer is relatively fixed,and the arrangement of spring and friction damper is flexible.The position and number can be adjusted according to the isolation requirements,which has modular characteristics.The design method of the bearing is introduced.The calculations of the main components of MMSIB,i.e.,linear guide,spring and friction damper,are introduced in detail.The force-displacement curve of MMSIB was presented.A simplified multi-particle simulation model was established to calculate the seismic response of equipment,freestanding culture relic and MMSIB using ABAQUS.2.Shaking table test of a seismic isolated tall flexible electrical equipment was carried out.Tall flexible electrical equipment has a high center of gravity and a large slenderness ratio,which is prone to overturning damage under earthquake.A 110 kV current transformer(CT)and a seismic isolated CT were tested using shaking table and their seismic resonposes were comparied.The effectiveness of the MMSIB and the feasibility of the design method were verified.The MMSIB has good and stable isolation effect and strong anti-overturning ability,which can meet the needs of high-flexible electrical equipment layer isolation.The vertical input has adverse effect on the performance of MMSIB,the deformation is increased.The dynamic amplification effect of support and inherent capacity of electrical equipment should be considered in seismic isolation design.The design objective should be carefully determined to avoid reaching ultimate deformation of the isolation bearing.3.Shaking table test of a seismic isolated freestanding vase was carried out.The freestanding vase has the disadvantages of low strength,cracking tendency,irregularity and high center of gravity.Therefore,they are prone to be damaged when subjected to earthquakes.The feasibility of MMSIB for small freestanding culture relic was verified using shaking table test of a freestanding vase.The MMSIB has good and stable isolation effect and self-centering ability.The sliding and overturning phenomena of cultural relics are consistent with the calculation results.The MMSIB can prevent the vase from overturning under seismic exicitation.In the design of MMSIB for small cultural relics,reduction ratio of acceleration,demand of bearing displacement,limitation of bearing deformation,self-centering ability,etc.,should be fully considered.These targets are sometimes difficult to meet at the same time,trade-offs are needed.4.The recommended design parameters of MMSIB were presented.The analysis software of MMSIB was developed based on MATLAB and ABAQUS.The typical design of 400 × 400mm,600 × 600mm,800 × 800mm and 1000 × 1000mm MMSIB are given.The relationships between bearing size,spring stiffness,friction force and upper isolated mass,acceleration reduction ratio,maximum deformation and residual deformation are further discussed.