Aseismic base isolation: review and bibliography

Nonlinear natural rubber bearings for seismic isolation

A non-contact passive magnetic bearing has a low friction compared with other passive (journal or ball) bearings. But these bearings have negligible damping due to which even small rotor vibration impacts the bearing magnet. It results in breakage of brittle magnetic materials. To overcome this problem, a hybrid bearing (passive magnet+elastomer) has been proposed in the present manuscript. To select an appropriate rubber, a step-by-step approach, using pendulum and hysteresis tests, has been followed. A parametric study on thickness of selected rubber was carried out. Experiments were conducted on three configurations: (i) a stand-alone magnetic bearing, (ii) magnetic bearing with a butyl rubber having a thickness of 1mm, and (iii) magnetic bearing with a butyl rubber having a thickness of 1.5mm. To investigate the effect of rubber Young’s modulus on the damping, rubber was made softer by immersing in aromatic liquid, and the experiments were repeated using softer rubber. Copyright © 2014 John Wiley & Sons, Ltd.

https://web.iitd.ac.in/~hirani/lijesh-lubrication-science.pdf

Stiffness and damping coefficients for rubber mounted hybrid bearing

16. Abstract A two-dimensional nonlinear p-version finite element method is developed for the analysis of boundary value problems relevant to elastomeric bridge bearings. The method incorporates polynomial shape functions of the hierarchic type for the modeling of large-deformations rubber elasticity. ·In addition, a frictional-contact algorithm based on a penalty formulation and suitable for the interaction of the pad with rigid flat surfaces is derived and implemented. The J2 -flow theory with isotropic hardening is utilized to model the reinforcing steel as a bilinear elastoplastic material. Examples are presented to illustrate the performance of the element and some guidelines for the selection of appropriate orders of interpolation and integration rules. The results of a study performed to examine the effects of several design parameters of the bearing are presented. Comparisons with experimental findings are shown. A dynamic lumped model for the walking of the bearing is developed. Viscous frictional interfaces with the girder and the abutment are included. Several cases are analyzed to investigate the factors that affect this phenomenon.

Analysis of elastomeric bridge bearings

A composite characterization and accompanying finite element analysis for layered systems is presented. The model is developed for plane strain and axisymmetric (horizontal layers) configurations with stiff, relatively thin isotropic layers of reinforcement sandwiched between layers of relatively flexible isotropic matrix material. Potential applications include elastomeric bearings and reinforced earth structures. The composite theory, in addition to capturing the overall response characteristics of the layered system, approximately models the important edge effects which occur at boundaries and the stress concentrations at layer interfaces. The primary dependent variables for the composite theory have been selected such that the highest derivatives appearing in the strain energy function are first order, thus requiring only C\do continuity of the finite element approximations. As a result, the accompanying finite analysis is simple and computationally efficient. Numerical examples are presented to verify the theory, compare it to previous results, and to illustrate potential applications of the analysis.

C.J. Derham

Papers

The design and use of rubber bearings for vibration isolation and seismic protection of structures