Driven Pile Design: An Alternative Considering Pile Behavior under Service and Drag Loads

This project on the southeastern coast of the United States consisted of several structures supported on driven precast pre-stressed concrete (PPC) piles. The driven pile foundation was initially designed utilizing guidance from American Association of State Highway and Transportation Officials’ LRFD Bridge Design Specifications. Using AASHTO LRFD Bridge Design Specifications, the pile lengths and corresponding nominal resistance increased significantly to satisfy design requirements related to downdrag. A result of the longer piles was excessive pile drive time and a risk of pile damage. The driven pile foundation was subsequently redesigned utilizing methods that consider pile behavior under the service load, including drag loads associated with the presence of a compressible layer loaded by several feet of fill. The Neutral Plane method, in general accordance with the Federal Highway Administration (FHWA) Publication No. FHWA-NHI-16-009 guidance document, was incorporated to model pile behavior. The results of the model allowed utilization of shorter piles, which resulted in easier installation and significant time and materials savings.