Publication Abstract

Proceedings of the 39th Annual Conference on Deep Foundations, 2014, Atlanta, GA, USA, (DFI)

Calibration of the Gates Pile Driving Equation for LRFD in Louisiana
Glenn J. Rix, Robert C. Bachus and Raphael Siebenmann, Geosyntec Consultants, Inc. Eduardo Tavera, GeoStellar Engineering, LLC, Jongwon Jung, Louisiana State University, Zhongjie Zhang, Louisiana Transportation Research Center

The Louisiana Department of Transportation and Development (LADOTD) uses a variation of the FHWA-modified Gates equation to verify the nominal pile bearing resistance, typically on smaller projects where static load tests and dynamic monitoring are not practical. An inconsistency in the resistance factors for load and resistance factor design (LRFD) penalizes the target pile capacity needed during field observation if the LADOTD dynamic formula equation is used, which is unreasonable, and has created confusion among designers, consultants, district personnel, and inspectors in Louisiana. The objectives of this project are to recalibrate the FHWA-modified Gates equation and update the associated LRFD resistance factor for pile types and local soil conditions encountered in Louisiana. Improved consistency relative to the current design approaches will be achieved if the updated resistance factor matches or exceeds the worst-case resistance factor used by LADOTD, which will reduce confusion among users. Updating the resistance factor will also serve to increase confidence in the FHWA modified Gates equation, optimize the efficiency of the piles, and reduce project costs.

 article #1992; publication #1011 (AM-2014)