Preliminary Study On The Mechanical And Seismic Isolation Performance Of X-Shaped Rubber Bearings

At present,laminated rubber bearings are often used in seismic isolation technology,but traditional cylindrical laminated rubber bearings are prone to excessive deformation and compression shear failure under rare or extremely rare seismic effects.Aiming at how to deal with the failure prevention and control of bearings when the displacement of isolation layer exceeds the design displacement limit of isolation layer,the research of X-shaped rubber bearings is carried out.According to the mechanical characteristics of X-shaped rubber bearing,the horizontal stiffness characteristics and the compression-shear critical bearing capacity of X-shaped rubber bearing were studied.The differences in mechanical properties between X-shaped rubber bearings and traditional cylindrical laminated rubber bearings under compression and compression-shear stresses were compared by using numerical analysis.At the same time,X-shaped rubber bearings are applied to earthquake isolated buildings,and the seismic responses of X-shaped rubber bearings and traditional cylindrical laminated rubber bearings are compared and analyzed.The main research work carried out in this paper is as follows:(1)Discusses the problems of stability and compression-shear deformation failure of rubber seismic isolation bearings and the current status of deformation prevention and control failure,and introduces the geometric characteristics of an X-shaped rubber seismic isolation bearing.(2)Based on the analysis of the horizontal mechanical characteristics of the laminated rubber bearing,the compression-shear critical bearing capacity and the geometric characteristics of X-shaped rubber bearing,the mechanical characteristics of X-shaped rubber bearing,including the horizontal stiffness,the effective pressure area in compression-shear state and the compression-shear critical bearing capacity are discussed and analyzed.(3)Designed and fabricated X-shaped rubber bearing specimens,and studied the horizontal stiffness performance of X-shaped rubber bearing through the test.Then,based on the geometric characteristics of traditional cylindrical laminated rubber bearings,such as the thickness and diameter of the rubber layer,as well as the outer diameter of the X-shaped rubber bearing,four types of traditional cylindrical laminated rubber bearings and six types of X-shaped rubber bearings are designed.The difference between the horizontal stiffness of the X-shaped rubber bearing and the traditional cylindrical laminated rubber bearing is further analyzed by means of finite element numerical analysis.The results show that by forming an X-shaped rubber bearing on traditional cylindrical laminated rubber bearings,there is a certain increase in the horizontal stiffness of the bearing,but the relative impact is relatively small.(4)According to the designed X-shaped rubber bearing and the traditional cylindrical laminated rubber bearing using the method of finite element numerical analysis of its compression and compression-shear force analysis.Analyze the stress and strain distribution of each bearing,and then analyze its compression bearing capacity and compression-shear critical bearing capacity.At the same time,the ultimate horizontal deformation capacity of X-shaped rubber bearing under design compressive stress is studied.The results indicate that the X-shaped rubber bearing has a high critical bearing capacity for compression and compression shear,and the deformation capacity of the bearing has been greatly improved compared to the traditional cylindrical laminated rubber bearing.(5)Seismic isolation buildings with X-shaped rubber bearings and traditional cylindrical laminated rubber bearings are established,and the seismic response calculations for rare and extremely rare earthquakes with a seismic fortification intensity of 8 degrees are performed using the method of dynamic time history analysis.By analyzing its seismic isolation bearing displacement response,the absolute acceleration response of the first floor of the building and the inter-story displacement response of the building,we compare the seismic response of X-shaped rubber bearing and traditional cylindrical laminated rubber bearing and the failure prevention and control ability of large deformation.The results show that X-shaped rubber bearings can prevent excessive deformation of the isolation layer under rare earthquakes,resulting in isolation failure,and ensure the overall safety of the isolated building.