Evaluation of Predicted Pavement Response Using Measured Tire Contact Stresses (05-1566)
Dae-Wook Park, Kunsan National University, South Korea
Emmanuel G. Fernando, Texas A&M Transportation Institute
Josef Leidy, No Organization

A uniform circular vertical contact stress is commonly assumed in representing wheel loads in pavement analysis procedures. However, experimental measurements have shown that the actual loading conditions are non-uniform and depend on the tire construction, tire load and tire inflation pressure. In this paper, comparisons are presented of the predicted pavement response from three-dimensional (3D) finite element (FE) and layered elastic programs. The objective was to establish guidelines on how wheel loads may be modeled in currently implemented layered elastic pavement analysis programs to provide a better approximation of pavement response parameters for pavement design and evaluation purposes. To carry out this objective, tire contact pressure measurements were conducted with the stress-in-motion (SIM) pad developed in South Africa. Additionally, researchers obtained available tire contact pressure measurements from a previous study conducted at the University of California at Berkeley. Researchers used available contact pressure measurements on four tires to predict pavement response using a 3D finite element program, which permitted input of the measured tire contact pressures at various tire loads and tire inflation pressures. In these analyses, the horizontal strain at the bottom of the asphalt layer, compressive strain at the top of the subgrade, and the principal stresses at different depths were predicted. Similar predictions were generated using layered elastic theory with two different representations of the contact pressure and contact area. From the predicted strains, researchers estimated service life for a range of pavements, tire load and tire inflation pressures using limiting strain criteria. In addition, Mohr-Coulomb (MC) yield function values were calculated from the predicted principal stresses at different depths. The MC yield function values and pavement life estimates from the 3D FE and layered elastic analyses were compared to establish guidelines with respect to modeling wheel loads using existing layered elastic procedures.