The first portion of this paper summarizes classical concepts of work, or strain energy, as applied to the analysis of stresses, strains, and deflections under various vehicular load configurations on pavement systems. Controlling equations for strain energy density are presented. When considering strain energy density, strain energy, or work, all components of stresses or strains must be taken into account so that total internal behavior can be evaluated. Previously, pavement thickness design systems have been developed using only a single component of strain, typically at the bottom of the asphaltic concrete layer or at the top of the subgrade. Strain energy concepts permit modifications to thickness design systems to account for the net effect of all components of strains or stresses.

The second portion of this paper illustrates the significance of detailed analyses. Effects of loads and load distributions on vehicles are summarized. One startling result shows the large increase in fatigue rate due to unequal distribution of loads between the two axles of a tandem group relative to the fatigue under an equal load distribution.

A third part of this paper deals with pavement thickness designs for heavily loaded trucks exceeding legal load limits. The effects of those vehicles on interstate pavements are compared to the effects of more normally loaded vehicles.

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The contents of this report reflect the views of the authors who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the University of Kentucky, the Kentucky Transportation Cabinet, nor the Federal Highway Administration. This report does not constitute a standard, specification, or regulation.

Prepared for Presentation Annual Meeting Transportation Research Board (January, 1983).