Prediction of Viscoelastic Pavement Responses under Moving Load and Nonuniform Tire Contact Stresses Using 2.5-D Finite Element Method

This study developed two-and-half dimensional (2.5-D) finite element method (FEM) to predict viscoelastic pavement responses under moving loads and nonuniform tire contact stresses. The accuracy of 2.5-D FEM was validated with two analytical solutions for elastic and viscoelastic conditions. Compared to three-dimensional (3-D) FEM, the computational efficiency of the 2.5-D method was greatly improved. The effects of loading pattern and speed on pavement surface deflection and strain responses were analyzed for asphalt pavements with four different asphalt layer thicknesses. The analyzed pavement responses included surface deflections, maximum tensile strains in the asphalt layer, and maximum compressive strains on top of subgrade. The loading patterns have influence on the mechanical responses. According to the equivalent rule, the point load, rectangle type, and sinusoid-shape contact stresses were studied. It was found that the point load caused much greater pavement responses than that of the area-based loading. When the tire loading was simplified as uniform contact stress in rectangular area, the maximum tensile strains in the asphalt layer varied with the width/length ratio of contact area. Additionally, it was shown that the dynamic responses of pavement structure induced by the sinusoid-shape contact stresses and realistic nonuniform stresses were quite similar to each other in all the cases. The pavement strain responses decreased as the speed increased due to viscoelastic behavior of asphalt layer. The study results indicate that asphalt pavement responses under moving load can be calculated using the proposed 2.5-D FEM in a fast manner for mechanistic-empirical pavement design and analysis.