FINITE-ELEMENT ANALYSIS OF TEMPERATURE EFFECTS ON PLAIN-JOINTED CONCRETE PAVEMENTS

The finite-element study of the effect of temperature variation on pla in-jointed concrete pavements is presented. Temperature variation caus es curling and thermal-expansion stresses. Curling stresses result fro m temperature gradients through a slab depth. Thermal-expansion stress es are induced due to uniform changes in temperature that cause the sl ab to expand. The developed three-dimensional (3D) model consists of f our slabs separated by longitudinal and transverse joints. The interac tion between the ground and the concrete slab along with interaction a t the joints were modeled using interface elements. These elements gav e the model the capability to solve for partial contact between curled slabs and the ground to investigate the effect of compressive stresse s that may develop at the joints during curling, and to study the infl uence of friction between slabs and the ground. The data obtained usin g the finite-element model has shown reasonable agreement with the res ults 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 stu dies on curling and thermal-expansion stresses to study the effect of superposition of both stresses and to address the effect of uniform te mperature changes on joint opening. Another simpler model using nine l ayers across the depth of a pavement slab was used to introduce the ef fects of nonlinear temperature distribution. The results of the parame tric studies are presented and compared with other solutions. The arit hmetic addition of positive curling stresses and thermal-expansion str esses were less than those stresses obtained by superposition. In some cases, the calculated joint openings were higher than the allowable j oint 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.