Deflection and stress analysis of concrete slab under temperature and axle load coupling

A concrete slab edge will tend to curl up when it is subjected to a negative temperature gradient extending through the slab thickness. The tendency to curl up can induce tensile stresses on the top of slab as the pavement is restrained by its weight or other factors. At present in cement concrete pavement design in China the total stress as a result of load stress plus temperature stress results in transverse crack from the bottom to top of the slab is the only transverse crack considered. In recently many researchers have noticed top-down cracks in concrete pavement slab, and the top-down cracking has been observed in China through coring. Therefore, in order to understand the influences of coupling curling and loading stress on slab cracking, the single slab resting on elastic foundation with frictionless interface is simulated by finite element model (FEM). In FEM the axle load positions from an edge of the slab to another edge are considered and the negative temperature gradients are considered also. From the calculated results when a negative temperature gradient is combined with an axle load, high tensile stress will occur on the top of slab, so top-down cracking will occur. Therefore, in concrete pavement design the top-down cracking in concrete pavement should be considered in the design.