Bridge Abutment Nonlinear Force-Displacement-Capacity Prediction for Seismic Design

Abstract

Formulation of the mobilized force-displacement-capacity for the seismic design of a bridge abutment–embankment system is presented herein. As part of the seismic design philosophy of bridge structures, a realistic prediction of the abutment–embankment participation should be included in the bridge demand and capacity assessments. The nonlinear force-displacement capacity and/or stiffness of a bridge abutment–embankment system is a function of the abutment height, embankment soil properties (mobilized soil resistance), and the mobilized interface friction angle between the embankment and bridge abutment. A method based on a limit equilibrium logarithmic spiral, method of slices, coupled with characterization of the stress-strain behavior of the soil is employed. The stress-strain characterization relies on standard triaxial test results. The use of Mohr–Coulomb strength criteria based on mobilized strength parameters allows the consideration of a developing mobilized surface via limit equilibrium. The stress-strain behavior of soil in conjunction with the developing (mobilized) abutment–soil resistance surface is evaluated to assess the corresponding displacement. The nonlinear force-displacement response of different types of abutment–soil combinations (sand, clay, and