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Shock and Vibration
Volume 2015 (2015), Article ID 183756, 15 pages
http://dx.doi.org/10.1155/2015/183756
Research Article

Seismic Response Analysis of Continuous Multispan Bridges with Partial Isolation

1Department of Construction, Civil Engineering and Architecture (DICEA), Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona, Italy
2School of Architecture and Design (SAD), University of Camerino, Viale della Rimembranza, 63100 Ascoli Piceno, Italy

Received 17 December 2014; Accepted 23 March 2015

Academic Editor: Laurent Mevel

Copyright © 2015 E. Tubaldi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Partially isolated bridges are a particular class of bridges in which isolation bearings are placed only between the piers top and the deck whereas seismic stoppers restrain the transverse motion of the deck at the abutments. This paper proposes an analytical formulation for the seismic analysis of these bridges, modelled as beams with intermediate viscoelastic restraints whose properties describe the pier-isolator behaviour. Different techniques are developed for solving the seismic problem. The first technique employs the complex mode superposition method and provides an exact benchmark solution to the problem at hand. The two other simplified techniques are based on an approximation of the displacement field and are useful for preliminary assessment and design purposes. A realistic bridge is considered as case study and its seismic response under a set of ground motion records is analyzed. First, the complex mode superposition method is applied to study the characteristic features of the dynamic and seismic response of the system. A parametric analysis is carried out to evaluate the influence of support stiffness and damping on the seismic performance. Then, a comparison is made between the exact solution and the approximate solutions in order to evaluate the accuracy and suitability of the simplified analysis techniques for evaluating the seismic response of partially isolated bridges.