Linking site investigation efforts to final design savings with simplified reliability-based design methods

Abstract

This study aims to address how efforts spent in geotechnical site investigation can be linked in an objective and defensible way to the final design dimensions of a geotechnical structure.Apreviously developed pad foundation example is adopted for illustration. Three aspects of geotechnical information are addressed: a variety of in situ and laboratory tests, precision of the tests, and local experiences in the estimation of soil properties that permit reduction of transformation uncertainties between test indexes and design parameters. Four simplified reliabilitybased design methods based on partial factors and quantiles are calibrated for the pad foundation. Their performances in linking site investigation efforts to final design savings are studied. Among these methods, the quantile methods are found to be the most responsive to the availability of geotechnical information, whether in the form of site investigation efforts or local experiences. The quantile methods can fill a critical gap in current design practice, that is, to monetize the value of geotechnical information in the form of an increase/reduction of construction costs associated with changes in design dimensions in an objective and defensible way that can be communicated to nonengineers. © 2013 American Society of Civil Engineers.