The aim of this research is to study the behavior of flexible pavement under
wheel and thermal loading conditions using the finite element program ANSYS V
(5.4). The stress states distribution within the asphalt concrete pavement that
influence the direction of crack propagation have been investigated. The obtained
results from ANSYS finite element program show that a maximum stress intensity
factor value obtained at surface and then decrease with depth about (0.75 of
asphalt layer thickness) due to reduction in temperature in asphalt layer, which
indicates that crack will initiate at surface and extend throughout asphalt layer.
The horizontal stress for both top and bottom layers increase with the variation of
thermal coefficient expansion factor. High values of stresses at top surface of
asphalt layer due to high contact stress were induced under wheel and thermal
load conditions. As a result the highway pavement exhibited propagation of
surface –initiated cracks. Field observation of cores extracted from asphalt
concrete pavement confirmed the obtained results.