Seismic-Induced Deformations of a Geosynthetic Reinforced Soil Bridge Abutment Subjected to Longitudinal Shaking

Although geosynthetic-reinforced soil (GRS) bridge abutments have been used widely in highway infrastructure projects, understanding their response during earthquake loading is a remaining issue that is affecting their implementation throughout the U.S. In particular, the three-dimensional (3D) seismic response of GRS bridge abutments is critical to consider as the direction of shaking in the field may be uncertain and because experimental work has shown that it is possible to have horizontal deformations in directions other than the primary direction of shaking. Further, any horizontal deformations of the GRS bridge abutment may be linked with settlements of the bridge seat, so 3D deformations are important to understand. This study involves 3D numerical simulations of the seismic response of a hypothetical GRS bridge abutment experiencing one-dimensional horizontal shaking in the longitudinal direction of the bridge beam, focusing on the lateral deformations of the GRS bridge abutment in the longitudinal and the transverse directions. Time histories of the horizontal deformations in both directions are presented and synthesized with settlements of the bridge seat to evaluate the applicability of using the Federal Highway Administration (FHWA) design method linking vertical and lateral static deformations by assuming zero-volume change in the GRS mass to seismic loading.