Development of Environmental Contours from Site-Specific Regression Parameters of Load–Settlement Curves for Piles: The Global Database

Abstract

A database was compiled to establish the site-specific measured load–displacement responses of piles from different sites across the globe, which contains 188 curves from 12 sites. A curve-fitting technique was applied to each measured curve by using a two-parametric power law regression modeling. For an entire construction site, the scatter in the load–displacement behavior of multiple curves was incorporated in the uncertainty of the regression pairs. Consequently, environmental contours for regression pairs were developed by using the Nataf transformation or a normal copula. Such a contour was generated to quantify the uncertainty in the regression pairs in which the target reliability index of piles is specified, as demonstrated in various cases with two, three, and four variables. Most importantly, the environmental contour bounded by the serviceability limit state of piles at each site was presented and the reliability index was solved through an evolution of the environmental contours. The computed reliability index of the bearing resistance for piles was compared with the values yielded by the geometric reliability analysis and the first-order reliability method (FORM). Since the reliability index was solved in the original physical variable space, it made the reliability theory easy to understand. Such a site-specific reliability assessment of piles could be helpful for a practical project to implement quality control during the construction of pile foundations.