Curved Integral Abutment Bridges — Thermal Response Predictions through Finite Element Analysis

Integral abutment bridges (IAB) are common types of bridges that are designed to avoid maintenance problems occurring due to corrosion, creep and fatigue at connection elements such as expansion joints, bearings and roller supports. Deterioration of these connection elements may cause corrosion in structural elements and higher bridge maintenance costs. Performance of IABs is primarily governed by seasonal thermal changes, which subject abutments and piles to large deformations. These thermal movements are dependent on the superstructure material and geometry. Past research on this type of bridge has included real time field monitoring and finite element analyses on straight bridges with and without skew. Outcomes of these research studies have been used to form the basis for several guidelines on IAB design developed by state departments of transportation (DOT). Contrastingly, research on curved IABs are scarce and since, by virtue of their geometry response of the curved integral bridges to thermal loadings are complicated, most DOTs have restricted the design of curved girders for IABs. This paper presents results from finite element modeling of curved integral abutment bridges using the structural characteristics of a curved IAB in Vermont. The bridge models differed by varying the degree of curvature of the superstructure and backfill material properties. The influence of these two parameters on IAB thermal response were quantified through comparison of longitudinal and vertical deformations of the bridge deck, abutment displacements and rotations, weak and strong axis pile moments, and backfill pressures behind abutments. The models included five different degrees of curvature ranging from 0° (straight bridge) to 50°. For each model two different backfill properties (loose sand and dense sand) were used.