Large-Diameter Pipe Piles Driven for Ebey Slough Bridge Replacement Project,Marysville,Washington

This paper presents a case study of large-diameter open-end steel pipe piles for the Ebey Slough Bridge Replacement Project. The new Ebey Slough Bridge was an approximately 700-ft-long, four-lane bridge over Ebey Slough in Marysville, Washington. The project site was underlain by more than 300 ft of very loose to medium dense silt, silty sand, and silty clay. New bridge foundations consisted of 4- and 6-ft-diameter open-end steel pipe piles driven to depths ranging from approximately 150 to 240 ft. Geotechnical design of the open-end pipe piles was performed by Shannon & Wilson, Inc. Total pile compressive resistances were confirmed through a dynamic test pile program during pile installation. The static design methods provided in AASHTO are compared here to results of the dynamic test pile program. Results of the dynamic test program suggest that static design methods overestimate nominal side resistance of 4- and 6-ft-diameter open-end pipe piles. Comparison of factored side resistances using the static design methods and AASHTO resistance factors suggest potential limitations of AASHTO resistance factors for large-diameter piles.