Thermal Stress Analysis in Concrete Pavements

Abstract

Temperature changing within 24 h causes different deformations of concrete slabs. In consequence, thermal stresses arise in the slabs due to their dead weight and lateral constraints. In Central Europe, due to frequently changing air circulations, concrete pavements are subjected to varying thermal impacts during the year as well as day and night. So far in Poland, there are no studies of thermal effects on concrete pavements. This paper presents an analysis of varied conditions prevailing in Central Europe in the case of Poland. We report original measurements of the distribution of temperature in concrete pavements. A relationship between 24-h temperature fluctuations and thermal differences occurring in concrete slabs was analyzed. We numerically analyzed the daily range of overall average air temperatures, which better correlates with thermal difference in concrete slabs than the ambient air temperature. The analysis of thermal stresses occurring in concrete slabs, depending on their length and variable thermal differences corresponding to different seasons, was carried out. three-dimensional (3D) FEM (finite-element method) computations show that stresses of 1 MPa arise in slabs longer than 5 m at the positive difference characteristic of the summer (10°C). Stresses in these slabs can reach over 1.5 MPa for incidental temperature impacts, that is, a positive difference of 20°C. Stress values for two slab thicknesses, 25 and 30 cm, were compared. It was found that higher (about 5%) stresses arise in the slab 25 cm thick and shorter than 4.5 m rather than in the 30-cm-thick slab. The analyses can be helpful in designing new concrete pavements as well as in estimating the load-bearing capacity of the existing structures.