Abstract
This paper presents one of the geotechnical initiatives in reliability-based code development that has been sponsored by the Electric Power Research Institute for transmission line structure foundations. The framework for the development of a practical reliability-based design approach is illustrated using the design of drilled shafts (bored piles) for uplift under undrained loading. A target reliability index of 3.2 is selected based on the reliability indices implied by existing working stress designs. Two simple design formats (load and resistance factor design and multiple resistance factor design) are rigorously calibrated using the first-order reliability method to produce designs that achieve a known level of reliability consistently.