Load and Resistance Factors and Design Parameter Offsets for Mechanistic–Empirical Pavement Design Guide

An approach to developing load and resistance factors and design parameter offsets for inputs to the Mechanistic–Empirical Pavement Design Guide (MEPDG) is provided for the purpose of ensuring, with a high level of probability, that the MEPDG-predicted distress at any level of reliability does not exceed a given threshold. In the proposed approach, the two most significant sources of uncertainty in pavement design—input variability and model prediction error—are handled separately. The proposed method involves four major steps: experimental design, surrogate model estimation, model verification, and calculation of load and resistance factors and design offsets with the inverse first-order reliability method. The proposed method allows pavement engineers to account for uncertainty in loading and resistance parameters in a similar manner to the load and resistance factor design provisions of the American Institute of Steel Construction's Steel Construction Manual and the American Concrete Institute's ACI 318: Building Code Requirements for Structural Concrete. The proposed methods are illustrated for a typical flexible pavement.