Strain Energy Analysis of Pavement Designs for Heavy Trucks

Abstract

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 are summarized and 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 one 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. Effects of loads and distribution of loads 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 rate caused by an equal load distribution. Damage factors and pavement thickness designs for heavily loaded trucks exceeding legal load limits are also discussed. The effects of those vehicles on Interstate pavements are compared to the effects of more normally loaded vehicles. (Author)