Finite-Element Analysis of Temperature Effects on Plain-Jointed Concrete Pavements
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The finite-element study of the effect of temperature variation on plain-jointed concrete pavements is presented. Temperature variation causes curling and thermal-expansion stresses. Curling stresses result from temperature gradients through a slab depth. Thermal-expansion stresses are induced due to uniform changes in temperature that cause the slab to expand. The developed three-dimensional (3D) model consists of four slabs separated by longitudinal and transverse joints. The interaction between the ground and the concrete slab along with interaction at the joints were modeled using interface elements. These elements gave the model the capability to solve for partial contact between curled slabs and the ground to investigate the effect of compressive stresses that may develop at the joints during curling, and to study the influence of friction between slabs and the ground. The data obtained using the finite-element model has shown reasonable agreement with the results obtained from three computer models: KENSLABS, ILLI-SLAB, JSLAB, and the analytical solution proposed by Bradbury. The best correlation was obtained with JSLAB. The model was used to perform parametric studies on curling and thermal-expansion stresses to study the effect of superposition of both stresses and to address the effect of uniform temperature changes on joint opening. Another simpler model using nine layers across the depth of a pavement slab was used to introduce the effects of nonlinear temperature distribution. The results of the parametric studies are presented and compared with other solutions. The arithmetic addition of positive curling stresses and thermal-expansion stresses were less than those stresses obtained by superposition. In some cases, the calculated joint openings were higher than the allowable joint opening. Nonlinear temperature distribution caused higher tensile stresses than the linear distribution of temperature. The difference in tensile stresses between the two distributions was approximately 3-13% of the modulus of rupture of concrete.