Nonlinear Response of Medium Size Continuous Bridges with LRB

Abstract

—The main objectives of this work were to investigate the effects of the nonlinear behavior of the isolation pads on the seismic response of bridges with rubber bearings, and to identify when base isolation improved their seismic performance. To achieve these objectives a parametric study was conducted designing a set of bridges for three different soil types and varying the number of spans, span lengths, and pier heights. The seismic responses (accelerations, displacements and pier seismic forces) were evaluated for three different structural models. The first represented bridges without base isolation; the second corresponded to the same bridges including now rubber bearings with linear elastic behavior that shifted the natural period of the bridge by a factor of 2 to 4. In the third model the seismic response of the base isolated bridges was studied accounting for the nonlinear behavior of the pads. The results show clearly the importance of the nonlinear behavior on the seismic performance of the bridges.