UC San Diego

This paper presents an experimental study on the response of a half-scale geosynthetic reinforced soil (GRS) bridge abutment subjected to shaking in the direction transverse to the bridge beam. The specimen geometry, reinforcement stiffness, soil modulus, applied surcharge stress and characteristics of the earthquake motions were scaled according to established similitude relationships for shaking table tests in a 1g gravitational field. The GRS bridge abutment was constructed using modular facing blocks, well-graded angular sand and uniaxial geogrid reinforcement, in both the longitudinal and transverse directions. Facing displacements, bridge seat settlements, accelerations, vertical and lateral soil stresses, reinforcement strains, and bridge seat and bridge beam interactions were measured during a series of input motions. The average incremental residual bridge seat settlement was 4.7 mm after the Northridge motion, which corresponds to a vertical strain of 0.22% for the lower GRS fill. After the series of motions, the maximum residual tensile strains occurred near the facing block connections for the lowermost reinforcement layer and under the bridge seat for higher reinforcement layers.