Research Of Mechanical Properties Of Rubber Bearings With Initial Rotations

In recent years,with the development of isolation technology,more and more buildings use isolation technology.At present,isolation rubber bearings are usually set between the superstructure and the lower foundation in large-span spatial structures using isolation technology,so as to reduce the earthquake impact.However,in some established large-span spatial structures using rubber bearings,the upper and lower surfaces of the bearings often have certain rotation angles,which will inevitably have a direct impact on the mechanical properties and isolation effect of rubber isolation bearings.Based on this,the mechanical properties of rubber bearings with initial rotations are studied.The main research contents and conclusions are as follows:(1)Theoretical research.Based on the Haringx theory,the horizontal stiffness of rubber isolation bearings with initial rotations was deduced,and the theoretical model was used to analyze the influence of initial rotations on the horizontal stiffness of rubber bearings.The results show that the horizontal stiffness of rubber bearings with initial rotations is related to the loading direction of horizontal load,that is,it has directional effect.Based on this,the horizontal stiffness of rubber isolation bearings with initial rotations are studied from two directions: the same direction as the bearing rotation and the direction perpendicular to the bearing rotation,referring to rectangular bearings.(2)Experimental analysis.In order to verify the rationality of the theoretical calculation model and the finite element model,the rubber isolation bearing with initial angle was tested.The test contents include shear strain correlation test,pressure correlation test,repeated loading times correlation test and large deformation shear performance test under different initial angles.The results show that when the loading direction is the same as the rotation direction,the hysteresis curve is center symmetry,and when the loading direction is perpendicular to the rotation direction,the hysteresis curve is no longer the center symmetry,but rather to drift upwards,because of horizontal thrust due to rotation;compared with the rubber isolation bearing without rotations,the horizontal stiffness of the rubber isolation bearing with initial rotations is decreased,and the decrease amplitude increases with the increase of the angle.(3)Finite element analysis.The influence of initial rotations on mechanical properties of rubber bearings were studied by modeling bearings with ABAQUS,a large general finite element software.Finally,by changing the size of initial rotations,bearing size,vertical pressure,bearing first shape coefficient and bearing second shape coefficient,the parameters of rubber isolation bearing were analyzed.The results show that the results obtained by finite element analysis are in good agreement with the experimental results,which provides a basis for subsequent analysis.The influence of initial rotations on the horizontal stiffness of rubber bearings has a strong correlation with the size of initial rotation,the first shape coefficient of bearings and the second shape coefficient of bearings,and increases with the increase of initial rotations,the first shape coefficient of bearing and the second shape coefficient of bearing.Based on a large number of finite element data,a formula for calculating the horizontal stiffness of rubber bearings with initial rotations is proposed.