FATIGUE LIFE PREDICTION USING VISCO-ELASTIC ANALYSIS

Several pavements were tested with a wheel tracking device to determine the fatigue performance. The use of the visco-elastic method (with a dissipated energy criteria) was compared to elastic analysis for those pavements tested. Strains measured in test tracks show that, in the longitudinal direction, compressive strains occur which are followed by a tensile peak and then compressive strains again, whereas, in the transverse direction, the strain is all tensile. If a visco-elastic model is employed, non-symmetrical stress/strain responses can be calculated. Further analysis illustrates that, using asphalt material properties associated with a visco-elastic model, the effect of multiple wheel passes on the strain response could be explained with reasonable accuracy. Analysis of pavements produced a similar ranking to the performance obtained in the test pavements and indicated that as temperature is increased, life decreases, consistent with fatigue calculations by other techniques.