Modeling of Pile Footings and Drilled Shafts for Seismic Design

Keywords: Seismic design. Drilled shaft foundations. Pile group foundations. Bridges. Loading. Modeling. Stiffness. Lateral ground spreading. Seismic response. Soil pile interaction. Pile footings. Liquefiable soils.

Abstract: This report documents two studies that were conducted to review, assess, and provide recommendations regarding the seismic design of bridge foundations. Specifically, the report addresses modeling approaches and parameters that affect the seismic design and response of pile groups and drilled shafts. The report attempts to bridge the interface between the structural and geotechnical design process by describing a two-step design and analysis procedure for these bridge foundation components. Recent research results on pile group effects and the design of pile foundations to resist lateral spreading of liquefiable soils are also reviewed. Recommendations are provided concerning: modifications to p-y curves to account for cyclic loading conditions, pile group effects and soil-pile interaction behavior, and development of p-y curves for the design of drilled shafts.