EXPERIMENTAL AND NUMERICAL STUDY ON THE NONLINEAR MECHANICAL PROPERTIES OF OBLIQUE 3D ISOLATION BEARINGS

An oblique three-dimensional (3D) isolation bearing was introduced based on the properties of lead rubber bearings (LRB) to meet the vertical strength and damping demands. A mechanical model considering the influence of the pressure and nonlinear stiffness degradation of LRB was established. The horizontal and vertical performance test was carried out on the 3D isolation bearings with inclination angles of 12 degrees and 15 degrees. The hysteretic behavior had non-parallel characteristics during the loading and unloading process. The vertical stiffness showed a nonlinear variation with the deformation. The variation of the vertical performance with the inclination angle and the vertical displacement was obtained. The proposed nonlinear theory and experimental results matched well. A numerical simulation of the 3D isolation bearings with different inclination angles was accomplished using the finite element method. The variations of the vertical nonlinear stiffness with the friction coefficient, shear strain, and inclination angle were discussed based on the simulation results.