Research On The Seismic Performance Of RC Continuous Girder Bridge Considering Abutment-soil-structure Interaction

Bridges are one of the most crucial parts of the transportation network and studying its seismic performance during seismic events has profound theoretical and practical significance. Currently, the seismic design methods of short to moderate span multi-span continuous girder bridges are discussed in detail by domestic and foreign scholars, however, when previously evaluating the seismic performance of this type of bridges, the abutment-soil-structure interaction has not been taken into account. Therefore, it is necessary to strengthen the research in order to facilitate China's continuous improvements of bridge seismic design objectively. This topic is carried out with the support of the National Science Foundation(Contract No. 51278183)—‘Research on reasonable earthquake resisting system of bridge in mountain zone based on time-dependent fragility'. In this paper, a short to moderate span continuous girder bridge is selected, and the seismic performance of the bridge considering abutment-soil-structure interaction is studied. The main contents include:(1) Earthquake damage forms of bridges and the research achievements and developments of the interaction between abutment and backfill soils are introduced and reviewed, based on comprehensive reading and understanding of related literature home and abroad, it indicates that there is a need to accurately simulation the abutment-soil-structure interaction during seismic events; It describes the bridge seismic fragility analysis methods and research status.(2) Taking an existing reinforced concrete continuous girder bridge for example, the finite element software Open Sees is adopted to establish the nonlinear dynamic analysis model of the whole bridge, which discusses the mechanics simulation of the bridge main components including superstructure, bearings, pier columns, pile-soil interaction, expansion joints etc. and focuses on the abutment. This paper introduces the different ways of abutment simulation and all kinds of considerations of the abutment stiffness.(3) Based on the Open Sees nonlinear dynamic analysis model, the elastic-plastic and hyperbolic force-displacement relationship are employed to simulate the abutment stress behavior and three ground motion records are selected, the seismic response of the structure under each longitudinal seismic wave input is calculated through nonlinear time history response analysis. This paper studies the seismic response of the bridge considering the abutment-soil-structure interaction and explores the influence of the types of backfill soils on the dynamic response of the bridge.(4) The paper describes the process of building bridge seismic fragility curves, the input of seismic waves, the determination of damage index and probabilistic seismic demand analysis are discussed. Selecting 100 seismic records in the US Pacific Earthquake Engineering Research Center(PEER) strong earthquake ground motion database, the earthquake-bridge samples are analyzed through nonlinear time-history method for the bridge dynamic analysis model; the spectral acceleration(Sa) is chosen as ground motion intensity, the pier displacement ductility ratio is determined as the damage index and seismic fragility analysis is implemented; it studies the changes of fragility curves on pier columns considering the abutment-soil-structure interaction and discusses the influence of different backfill-soil types on fragility curves.