Development of dynamic fatigue failure criterion

When a truck wheel moves on the road, stress pulses develop within the pavement layers. These pulses are primarily functions of load magnitude, tire pressure, and vehicle speed. In this study, dynamic analysis is used to predict stresses and deflections that develop when a moving wheel load is applied. The method considers the inertial forces and assumes pulsating loads that accurately simulate actual wheel loading. The method is applied on AASHO road test sections to predict their theoretical response. The change of stresses and deflections at various loading times and at different speeds is computed and verified versus actual field data. Very close agreement was found between field deflections and theoretical predictions. The evaluated pavement response is used to develop a fatigue failure criterion for a speed of 30 mph, which is the mean speed at the AASHO road test. The use of accurate prediction models and valid failure functions may lead to better methods of design and rehabilitations of pavements.