Analytical Parameter Study for Class of Elastomeric Bearings

An analytical parameter study is conducted for a class of elastomeric bearings often used in base isolation systems and as bridge support bearings. The study is carried out using a recently developed nonlinear finite element analysis for such bearings. In order that the results be applicable to as wide a range of bearings as possible, a spectrum of sizes and properties is considered in the study and the results are presented in nondimensional form when possible. The loading conditions are compression, compression-shear, compression-bending and eccentric compression. Bearings of sufficient heights for buckling to occur are included in the study. Special attention is focused on the loss of shear and bending stiffness due to impending unstable behavior. End support conditions that do and do not allow for possible "lift-off" of the loading surface from the bearing are both included. Considering the wide spectrum of bearing types and loading conditions that occur in practice, the parameter study cannot be considered to be in any sense exhaustive; however, sufficient data are given to be of value in many design situations. Lastly, a modification of the traditional definition of "shape factor" for elastomeric bearings is proposed and results are given that indicate its use will lead to an improvement in the correlation of behaviors for bearings of diverse shapes.