The effect of loading conditions on pavement responses calculated using a linear-elastic model

In most structural pavement design methods, strains and stresses in the layers are calculated with multi-layer programs based on the Burmister model using the linear elastic theory. Burmister defined loads as a constant pressure applied on a circular surface. New technology for measuring tire-pavement contact stresses has shown that the assumptions used in the multi-layer models do not correspond to reality. This study evaluates the relative influence of different parameters, which diverge considerably from the assumptions made in the multi-layer models. For a constant vertical load and a constant inflation pressure of a super-single tire, calculations of the strains and stresses in a reference structure were made for various methods of load application. Variations concerned the shape of the load surface, the value of the applied mean vertical pressure, the distribution of the vertical load pressure on the load surface and the application of a transversal load. The evaluation of the strain and stress distributions was made at two critical depths in the structure: at the bottom and at the top of the bituminous layers. It was seen from this study carried out on a pavement with a total thickness of 170 mm for the bituminous layers, that the main parameter that influences the stress and strain distributions in the structure was the definition of the shape and the extent of the load surface. It was also noticed that transversal loads have non-negligible effects on the strains and stresses, even at the bottom of the bituminous layers.