A comparison of flexible pavement behavior under dual and flotation tires for static and moving loads.

The behaviour of flexible pavements under dual (9.00-20, 12-ply) and flotation (16. 5-19, 16-ply) tires with loading of 9,000 lbs. Is compared on the basis of deflection, curvature, the boussinesq solution, and the finite element method. Static deflection bowls are measured with a series of five benkelman beams and deflection profiles for moving loads are plotted by a special benkelman beam equipped with a dcdt, at three deflection levels (0.030, 0.050, and 0.250 in.), the maximum deflections and curvature (measured by ford and bissett's ratio and kung's slope of deflection) are more severe for the flotation tire. It is concluded, that for the structural sections and deflection levels considered, that this flotation tire is inferior to the dual tires in terms of anticipated pavement performance. The classical boussinesq solution indicates that the vertical stresses will be higher under the flotation tire than the dual tires. Preliminary finite element solutions (using an axi-symmetric program) for assumed material properties show the deflections to be greater under the flotation tire, and the importance of the ac modulus to the distribution of stresses in a layered system. The finite element method allows inhomogeneous, inelastic, anisotropic materials to be considered. /author/.