Stiffnesses of abutments on spread footings with cohesionless backfill

Characterization of bridge-abutment-backfill interaction is an important component in seismic bridge response evaluations. The paper presents a relatively simple and realistic methodology to evaluate the nonlinear translational (longitudinal, vertical, and transverse) spring stiffnesses to represent bridge-abutment-backfill interaction. Many important factors such as the nonlinear soil behavior, abutment dimensions, superstructure loads, and difference in soil behavior under active and passive conditions have been accounted for. Only routinely used soil properties are required in the model. The results predicted by the proposed approach have been calibrated against abutment stiffnesses (longitudinal and translational) measured in large-scale field tests. The agreement between the predicted and measured stiffnesses is very good. Subsequently, the approach has been used to develop normalized relationships for abutment stiffnesses.