ABSTRACT
In recent studies, calibrating resistance factors of drilled shafts were mainly performed for a common resistance factor. Uncertainties of predicted shaft and base resistances were lumped into a unique resistance factor. This approach has not fully taken advantage of the Load and Resistance Factor Design (LRFD) method, as opposed to when shaft and base resistance factors are calibrated separately. A dataset including 26 Osterberg cell-tested drilled shafts is analyzed and the differences between predicted and measured resistances for the shaft and base are statistically analyzed. A reliability-based analysis technique using Monte Carlo Simulation (MCS) is used to calibrate the resistance factors separately in the framework of the LRFD method with specified target reliability levels. Several benefits from the use of separating resistance factors on shaft and base are presented.
