Progressive Seismic Failure of a Highway Bridge, Including Abutment-Backfill Interaction

Abstract

Current engineering practice pays little attention, if any, to nonlinear abutment-backfill soil interaction (ABSI) effects on seismic behaviour of bridges. The primary focus of this article is to assess the influence of ABSI on the progressive seismic failure of bridge structures. Emphasis is placed on the significance of ABSI effects, including abutment behaviour and backfill soil flexibility. Nonlinear dynamic analysis is performed using a bilinear hysteretic model for the bridge superstructure and nonlinear characteristics of the expansion joint. Results indicate that ABSI has a significant effect on the seismic response in the longitudinal direction and can effectively reduce bridge seismic demands. ABSI affects rotational ductility demand at pier ends of the bridges, relative displacements, pounding and axial forces in the restrainers. Thus, it is essential that numerical models used in seismic assessment of bridge structures properly consider abutment-backfill interaction.Keywords: Abutment-backfill soil interaction, highway bridges, nonlinear dynamic analysis, seismic failure.HIGHWAY bridges represent structures of economic and strategic importance. They are generally built in reinforced or prestressed concrete to span over a valley, river, road or any physical obstacle to essentially allow the passage of all kinds of vehicles. High seismic performance is usually required for this special category of structures, the potential collapse of which can result an significant economic impact.Abutment modelling and behaviour 1 , soil conditions and foundation soil stiffness 2 , soil structure interaction 3 and embankment flexibility 4 have been found to significantly influence the response of bridge systems and eventually their seismic failure 5 under strong ground motions. In addition, analysis of past and recent bridge damage data has illustrated that seismic participation of bridge abutment and backfill soil can lead to cost-effective design of bridges 6 . The primary focus of this article is to assess the influence of abutment-backfill soil interaction (ABSI) on the progressive seismic failure of bridge structures. Emphasis is placed on the significance of ABSI effects, including abutment behaviour and flexibility of backfill soil at the abutments. The effective stiffness, foundation soil damping and capacity parameters at the base of the spread footings have been evaluated using FEMA procedures 7 . Yields strengths of abutment backfill in compression and in tension have been evaluated using Mononobe-Okabe pseudostatic approach for passive force and frictional sliding capacity at the abutment footing respectively. Nonlinear dynamic analysis is performed using a bilinear hysteretic model for the bridge superstructure and nonlinear characteristics of the expansion joint. Based on the results obtained in the present study, it is concluded that ABSI has significant influence on seismic demands of bridge systems and hence can lead to cost-effective design of bridge structures. However, special attention should be ...

Effects of Height and Number of Bays on the Seismic Behavior Factor of R.C. Moment-Resisting Frame Structures Including Soil-Structure Interaction

“…3D-FE (Finite Element) modeling of soil idealized as a continuum with solid elements could have been used. However, this would require a pertinent soil constitutive model and an experimental characterization of model parameters, further, the FE model for continuum soil modeling is complex as compared to nonlinear springs modeling which has the important advantages of simplicity in FE modeling, short CPU time, only few material parameters to be determined, simple connection of the springs to the study structure and the possibility to incorporate cyclic loading in reference (Ouanani and Tiliouine 2017).…”

Dynamic analysis of a multi-span simply supported prestressed concrete bridge with restrainers and seismic isolation devices

“…In addition to above pratical justifications, the damage data of bridges have also illustrated thatthe bridge components structural performance may be very sensitive to 3D components of ground motions (Tiliouine and Ouanani, 2012) and foundation soil flexibility including abutment-backfill soil (Ouanani and Tiliouine, 2017). This paper presents some results from an exhaustive investigation carried out on the dynamic analysis of amulti-span simply supported MSSS prestressed concrete bridge equipped with retrainers and seismic isolation devices at expansion joints and abutments including Soil Structure Interaction (SSI) effects.…”