Performance-Based Design Factors for Pile Foundations

The seismic design of pile foundations is currently performed in a relatively simple, deterministic manner. This report describes the development of a performance-based framework to create seismic designs of pile group foundations that consider all potential levels of loading and their likelihoods of occurrence in a particular area.

Because of the multitude of factors that can exist at a site, development of a complete, integrated procedure that would extend from ground motions to limit state exceedance was not practical. To make the problem more useful to the research sponsors, a modular approach was developed. The framework allows for the development and use of a structural model with a simplified representation of the foundation system. The discrete soil model was developed using an equivalent linear format so that stiffness and damping characteristics were consistent with deformation levels. The foundation loads computed in these analyses were then applied to a three-dimensional soil-pile group model to compute the resulting displacements and rotations of the pile cap.

A computer program was developed to perform the calculations required to develop load and resistance factors and demand and capacity factors. The calculations allow a designer to select a return period for limit state exceedance and then select the corresponding factors that will produce a design that corresponds to the desired limit state exceedance rate.
Publication Date: 
Thursday, October 16, 2014
Publication Number: 
WA-RD 827.1
Last modified: 
10/12/2016 - 15:42
Steven L. Kramer, Carlos Valdez, Benjamin Blanchette, Jack W. Baker.
Pacific Earthquake Engineering Research Center. College of Engineering. University of California, Berkeley.
Number of Pages: 
Pile foundations, Earthquake resistant design, Bridge engineering, Computer aided design, Design load, Ultimate load design.