Three-Dimensional Finite Element Study on Effects of Nonlinear Temperature Gradients in Concrete Pavements

A three-dimensional (3D) finite element (FE) model is developed to investigate whether the condition of plane sections remaining plane exists in concrete pavements subjected to nonlinear temperature gradients. This model is utilized to validate the analytical method proposed by Mohamed and Hansen. The 3D brick element is chosen so that the plane section condition is not imposed in the model, as compared with the model using the flat plate element. Furthermore, the possibility of loss of contact between the pavement slab and the subgrade is studied. The condition of full contact is investigated for a nonlinear temperature gradient that produces the maximum tensile stress in the slab according to the data used. Two slab lengths and two radii of relative stiffness are considered. It is found that plane sections remain plane for the entire slab except for a region very close to the free edges, which also establishes the boundary where solutions by Mohamed and Hansen are applicable. In both cases of the contact condition, the 3D FE model predicts no loss of contact between the slab and the subgrade.