Strain Distribution in the Asphalt Layer under Measured 3-D Tire-pavement Contact Stresses

ABSTRACT Most pavement design methodologies assume the tire-pavement contact stress is equal to the tire inflation pressure and uniformly distributed over a circular contact area. However, tire-pavement contact area is not in a circular shape and the contact stress is neither uniform nor equal to the tire inflation pressure. To precisely account for the effect of actual contact stress on pavement response, this study evaluates the horizontal strains at the bottom of the asphalt layer produced by measured 3-D non-uniform stresses applied on the pavement surface. A multi-layer linear-elastic computer program, CIRCLY, was used to estimate horizontal strains in longitudinal direction and transverse direction under a number of combinations of load, tire pressure and asphalt thickness. Results show that the uniform stress model underestimates the longitudinal strains under a combination of thin surface layer and low tire pressure, and underestimates the transverse strains under a combination of thin surfacing, low tire pressure and high wheel loading.