Seismic Design of Bridges on Lead‐Rubber Bearings

Abstract

This paper reports on a parametric study of the response of bridge superstructures supported on lead‐rubber bearings when subjected to the 1940 El Centro earthquake (N‐S component) and the 1966 Parkfield earthquake. The effect of parameters such as lead‐plug size and aspect ratio, bearing thickness and yield strength, pier, abutment, and superstructure stiffnesses, and different earthquake records were investigated. The results of the time‐history analyses by Turkington (1987) produced clear trends that are used in the design procedure proposed by Turkington et al. (1987, 1989). The trends showed that the presence of lead shifts the natural period of the structure and increases the amount of damping. The magnitude of the period change and damping decreases as the natural period of the structure increases or as the pier height increases. Lead‐rubber bearings are most effective when used in conjunction with stiff substructures and can be used to redistribute seismic forces between piers and abutments.