Seismic Response Analysis of Continuous Multispan Bridges with Partial Isolation

E Tubaldi,A Dall’Asta,L Dezi

doi:10.1155/2015/183756

E Tubaldi, A Dall’Asta + Show 1 more

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https://doi.org/10.1155/2015/183756

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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.

Highlights

Restrained seismically isolated bridges (PRSI) are a particular class of bridges isolated at intermediate supports and transversally restrained at abutments
The aim of this study is to develop an analytical formulation of the seismic problem of Partially restrained seismically isolated bridges (PRSI) bridges, modelled as nonclassically damped continuous systems, and a rigorous solution technique based on the complex mode superposition (CMS) method [12, 21,22,23,24]
This paper proposes a formulation and different analysis technique for the seismic assessment of partially restrained seismically isolated (PRSI) bridges

Summary

Introduction

Restrained seismically isolated bridges (PRSI) are a particular class of bridges isolated at intermediate supports and transversally restrained at abutments. This type of partial isolation is quite common in many bridges all over the world (see, e.g., [1,2,3,4]). An analytical model commonly employed for the analysis of the transverse behaviour of PRSI bridges consists in a continuous supported beam resting on discrete intermediate supports with viscoelastic behaviour representing the pier-bearing systems (see, e.g., [6, 8, 9]). The strongly inhomogeneous distribution of the dissipation properties along the bridge results in nonclassical damping and this makes the rigorous analysis of the analytical PRSI bridge model very demanding

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