Study Of Mechanical Properties And Earthquake Damping Performance Of Fiber Reinforced Rubber Seismic Isolation Bearing

China experiences frequent earthquakes,and its rural areas have a vast geographical expanse.However,due to economic difficulties and a weak awareness of earthquake resistance,most rural residents do not consider earthquake-resistant measures for their homes.Once an earthquake occurs,it will result in significant economic losses and casualties.This paper addresses the issue of inadequate seismic resistance in village and town buildings and develops a set of high-performance and cost-effective new-type simplified isolation techniques suitable for such constructions.The main research contents are as follows:(1)Develop a new type of simple seismic isolation bearing suitable for village buildings.A fiber-reinforced plastic(FRP)rubber isolation bearing is developed based on the economic level,construction environment,and organizational management status of villages and towns.A low-cost,chemically stable,and mechanically reliable FRP board is developed to replace the steel plate in traditional laminated rubber bearings.Tensile and bending tests are conducted to determine the mechanical properties of the FRP board.The experimental results show that the FRP board used in this study meets the mechanical requirements for replacing the steel plate in traditional laminated rubber isolation bearings.(2)Mechanical performance test of FRP seismic isolation bearing.The newly developed FRP rubber seismic isolation bearings are subjected to systematic mechanical properties tests,including vertical mechanical properties and horizontal shear mechanical properties,specifically vertical compression properties,horizontal shear properties,vertical limit properties,surface pressure correlation and shear strain correlation.The study shows that the vertical stiffness of the bearing is not greatly affected by the change of surface pressure,and the vertical stiffness of the bearing is stable.Under the same axial pressure condition,the horizontal stiffness of the bearing decreases and then increases with the increase of shear strain.The horizontal stiffness of the bearing has a soft characteristic with the increase of compressive stress,when the vertical surface pressure of the bearing increases from 5MPa to 15 MPa,the horizontal stiffness of the bearing decreases by 20%～30%.The ultimate performance test determines 10 MPa as the maximum allowable surface pressure of the bearing and300% shear strain as the shear ultimate strain of the bearing.(3)Finite element simulation analysis of FRP seismic isolation bearing.The numerical simulation study of FRP seismic isolation bearing is carried out by finite element software ABAQUS.Different parameter models of FRP isolation bearings are established to analyze the stress conditions of the internal FRP board and rubber layer under compression and shear states,as well as the influence of different bearing sizes on stress distribution during bearing operation.The impact of the thickness ratio between the internal stiffening plate and the rubber layer on bearing performance is also investigated.The research results show that increasing the planar dimensions of the bearings reduces the internal unbalanced moment and weakens the P-△ effect,with a more significant reduction observed with larger shear strains.Increasing the plate thickness ratio decreases the peak value of horizontal tensile stress but does not affect the distribution of horizontal stress.Moreover,an increase in the rubber layer thickness leads to an increase in vertical compressive stress peak.(4)Seismic isolation design method for FRP seismic isolated masonry structures.The design method of FRP seismic isolation bearing applied to masonry structure is proposed.ANSYS software was used to perform the elasto-plastic time analysis under multiple earthquakes,basic intensity earthquakes and rare earthquakes for two models of ordinary masonry structure and FRP seismically isolated masonry structure to verify the seismic performance of FRP seismically isolated bearings.Under multiple,basic intensity and rare earthquakes,the average values of interstory shear force in the first layer of the isolated structure are 23%,27% and 36% of the original structure,respectively,and the average values of maximum interstory overturning moment can be reduced to 19%,23% and 20% of the original structure,respectively,and the average values of displacement angle are reduced to 23%,23% and 25% of the original structure,respectively.The results of finite element analysis prove that the FRP seismic isolation bearings have good seismic isolation effect when applied to masonry structures.