Load and Resistance Factor Design (LRFD) Of Deep Foundations Using a Performance-Based Design Approach

Abstract

The Load and Resistance Factor Design (LRFD) methodology is being widely adopted for deep foundation design. The LRFD methodology can take many different forms depending upon the extent of the available data and the type of static capacity prediction models. This paper introduces a new performance-based design approach that incorporates the LRFD methodology. The application of this design approach is demonstrated for drilled displacement piles. Field load test data from drilled displacement piles installed at a single site is integrated within the developed approach to demonstrate a site specific reliability-based design methodology that satisfies performance-based requirements at both the strength and serviceability limit states. The t-z method is utilized along with Latin Hypercube sampling to calibrate LRFD resistance factors. The developed method reveals that design efficiency can be achieved simultaneously with safety in the design of deep foundation systems.