Load and Resistance Factor Design of Drilled Shafts in Sand

Abstract

Resistance factors are developed for drilled shafts for a design method based on soil variables. The uncertainties associated with the design variables and equations were systematically quantified, and Monte-Carlo simulations were performed to obtain the distributions of the shaft and base capacities. Both the base and shaft capacities were found to follow normal distributions, and the applied dead and live loads were assumed to follow normal and lognormal distributions, respectively. Reliability analysis was then performed to obtain the limit state and nominal resistances and loads for a variety of soil profiles and pile dimensions. The optimal dead- and live-load factors were subsequently obtained from the analysis. The optimal resistance factors were then adjusted for use with the load factors recommended by the Federal Highway Administration.