Three-Dimensional Nonlinear Finite-Element Soil-Abutment Structure Interaction Model for Skewed Bridges

TLDR: In this paper, the authors developed three-dimensional nonlinear finite-element models to estimate soil capacities behind a non-skewed and a skewed abutment wall as a function of wall displacement.

Abstract: Seismic design of bridges is based on a displacement-performance philosophy This type of bridge design requires that the geotechnical engineer provide abutment-embankment soil springs which are inherently nonlinear To date, a number of experiments have been performed to determine the nonlinear lateral force-displacement capacity of ordinary non-skewed bridge abutments, pile caps and walls Typical highway bridges are wide so that the abutment walls are much wider than they are tall Therefore, the nonlinear abutment backfill response behind a wide non-skewed abutment wall is essentially a two-dimensional plane-strain earth pressure problem However, the estimation of the lateral force-displacement capacity behind a skewed abutment wall is a three dimensional problem that involves bridge deck rotation during dynamic loading The capacity is developed from passive wedge failure in the soil mass which occurs when the frictional resistance along the bottom and the two sides of the wedge are mobilized The mobilized passive resistance is dependent on the bridge displacement, bridge geometry (bridge skew angle, deck width and height), the soil stress-strain properties of the abutment backfill, and ground motion characteristics In common abutment design practice, the abutment load-deformation relationship due to passive resistance is based on load test data or presumptive values where the wall is pushed normal to the soil However, the passive resistance and stiffness for the skewed wall is expected to be smaller than for the ordinary non-skewed abutment wall due to the bridge rotation A three-dimensional model is required to capture the geometry and capacity of the full passive soil wedge behind the skewed abutments walls The objective of this paper is to develop three-dimensional nonlinear finite-element models to estimate soil capacities behind a non-skewed and a skewed abutment wall as a function of wall displacement The predicted force-displacement capacities will be compared with the results obtained from a field load-deformation test of a wall pushed into typical structure backfill The nonlinear force-displacement relationship of the abutments can be used to evaluate the seismic performance of skewed highway bridges