Project Details

The conventional design methodology for axially loaded pile foundation utilizes a Factor of Safety to account for the uncertainty associated with various design variables. This practice, however, does not address uncertainty in a consistent and rational manner. The Load and Resistance Factor Design (LRFD) method utilizes load and resistance factors to account for uncertainty. These factors are obtained from the analysis of reliability of the soil/foundation system. Guidelines published in AASHTO (1994) call for the implementation of the LRFD method for bridges. Driven piles are commonly used for support of bridge foundation and the need to define the resistance factors for their design is urgent. AASHTO guidelines provide these factors for general soil conditions but these general factors are not appropriate for specific local conditions. Documentation in literature indicates that several users found that the AASHTO-recommended factors lead to inappropriate design conflicting with their experiences.​

The objective of the proposed study is to develop the resistance factors for the design of driven piles in North Carolina. AASHTO guidelines provide resistance factors that are reportedly inappropriate for the various regions of North Carolina. The resistance factors will be developed for the unique soil types of this state. These factors will be developed in the framework of 'reliability analysis' using PDA and static load test data embodying the uncertainty associated with soil parameters. The form of probability distribution function describing the pile resistance will be studied and the associated parameters will then be quantified. First order reliability method will then be used to formulate the relationship between the factors and the reliability.