Developing Resistance Factors for Design of Piles in Sand

Load and resistance factor design (LRFD) of foundations is an emerging design philosophy in the United States. Reliability analyses are the preferred tools to establish resistance factors, but the needed probabilistic information regarding design method uncertainty is difficult to obtain. This paper illustrates an approach to uncertainty assessment that seeks to isolate the various sources of uncertainty. Using this approach, reliability analysis is used to develop resistance factors for the design of driven pipe piles in sand. The resistance factor results are used to highlight some of the differences between design methods that are exposed by the proposed uncertainty assessment technique. This approach is key to helping engineers manage risk and assess the relative value of differing degrees and types of design knowledge.