ABSTRACT
Reliability-based design (RBD) is known to provide a rational basis for incorporating uncertainties in the design environment explicitly into the geotechnical design (e.g., pile length). However, one recurring criticism of RBD is that there is no particular reason to use it because it seems to produce designs comparable to the existing practice. In particular, the link between potential reduction of uncertainties resulting from collection of more information and how this reduction could translate to actual savings in design dimensions has remained a vague theoretical possibility so far. More information can be collected using two approaches. One approach is to take field measurements/samples at more locations, that is, increase the amount of data for a given test type. The second approach is to conduct more test types, for example, supplement standard penetration test (SPT) with cone penetration test (CPT). The former approach increases information quantitatively, while the latter approach increases information qualitatively. This distinction is important, particularly pertaining to reduction of bias in the estimation of design parameters such as the undrained shear strength. The first approach may be effective in improving precision, but is usually not effective in reducing estimation bias. Both approaches are typically carried out simultaneously in practice to varying degrees, depending on the needs of the project and economics.
