History of Transition From Allowable Stress Design to Load and Resistance Factor Design and Beyond

Abstract

The Standing Committee on Foundations for Bridges and Other Structures has supported the implementation of the load and resistance factors (LRFD) design philosophy into practice. The committee has contributed by hosting discussions on the advantages, issues, and impact of the implementation of the American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) into foundation design and other related fields. The background and a historical overview of the development of LRFD in bridge foundation design are presented in this paper. Several National Cooperative Highway Research Program (NCHRP) projects have been of paramount importance on this matter. Milestone research projects are described, and a perspective on the future of the field is drawn. This document is intended to be a roadmap through the most useful material to understand reliability analysis and its application to geotechnical engineering. It is intended to be of interest to those engineers charged with performing reliability-based calibration in need of a starting point. The primary literature and steps followed to develop the current AASHTO LRFD specifications are highlighted. This paper aims to contribute to the understanding and future improvement of the LRFD specifications.