EVALUATING THE JPCP CRACKING MODEL OF THE MECHANISTIC-EMPIRICAL PAVEMENT DESIGN GUIDE

摘要

The MEPDG cracking model is a performance-based component of the new pavement design guide developed as a result of Project R1-37A of the National Cooperative Highway Research Program of the National Research Council, Transportation Research Board, which exists in the form of a software tool. The pavement academic community has been lately involved in analysis aimed at the evaluation of reasonableness and accuracy of the tool, given that it introduces several inputs that had been ignored in traditional design tools. Among these studies, the most notorious have implemented sensitivity analysis approaches. This research work introduces the potential uses of several sensitivity analysis approaches in the context of evaluation of the MEPDG cracking model. It also addresses important issues regarding failure mechanisms and newly introduced inputs that lack understanding, such as the permanent built-in temperature gradient in concrete slabs; the research concludes that anomalies are present in the prediction of fatigue damage that causes top-down cracking and demonstrates how the results contradict the current engineering understanding of this failure mechanism and the MEPDG literature. It also addresses, from a qualitative stand, the nature and treatment the permanent built-in temperature gradient has received in the design of the algorithm and suggests that the empirical model should be revised. In regard to sensitivity analysis of the MEPDG cracking model, this research recommends some potential uses of 2k screening methods and points in the direction of Response Surface Methodology (RSM) for further non-linear analysis in order to arrive at more exhaustive sensitivity analysis tools that cover wide input ranges. A case-study is also explored in order to show, qualitatively and quantitatively, what the discrepancies are in the predictions of the MEPDG cracking model.