Limit State Design Considerations for Resilient Pavements

Abstract: Current design methodologies are based on the assumption that pavement distresses accumulate slowly with repeated applications of stress or strain cycles at amplitudes significantly smaller than the material’s ultimate strength. Pavements, however, may fail not only because of the large number of applied loads whose characteristics had been anticipated at the pavement design stage, but also by a number of loads significantly more detrimental than those expected, even though the latter may be much less frequent. This possibility becomes even more important when one considers pavement resilience, i.e., resistance to and speedy recovery from catastrophic events, which cause large variations in structural capacity over a relatively short period of time. A “limit state” may be expected to occur when overloads are applied during periods of considerable loss in pavement strength, e.g., following inundation during a hurricane. This paper ponders the potential for implementing a limit state design concept in pavement design, to complement current approaches. Because of the large scatter exhibited by fatigue data, it is recommended that performance prediction alternatives be sought through the implementation of sophisticated fracture mechanics concepts, which recognize the significance of the stress gradient in addition to the maximum stress, and account for specimen size effects. This exploration may be expected to lead to the derivation of simple yet comprehensive methods of predicting crack propagation by applying dimensional analysis. It is also suggested that fundamental approaches be sought to replace empirical/statistical constructs that lack verification by laboratory or field data, including Miner’s linear cumulative fatigue hypothesis. The objectives are to decrease reliance on so-called transfer functions, recognized as the weakest component in a pavement design, and to encourage careful assessment of the rational foundation of pavement design policies. A review of the literature pertaining to limit state design for steel, concrete and geotechnical structures elucidates both the prospects and obstacles in emulating such methodologies in pavement design.