Design of Slabs on Grade
Stresses in slabs on grade result from both imposed loads and volume changes of the concrete. The magnitude of these stresses depends upon factors such as the degree of continuity, subgrade strength and uniformity, method of construction, quality of construction, and magnitude and position of the loads. In most cases, the effects of these factors can only be evaluated by making simplifying assumptions with respect to material properties and soil-structure interaction. The following sections briefly review some of the theories that have been proposed for the design of soil-supported concrete slabs.
The design methods for slabs on grade are based on theories originally developed for airport and highway pavements. An early attempt at a rational approach to design was made around 1920, when Westergaard’ proposed the so-called “corner formula” for stresses. Although the observations in the first road test with rigid pavements seemed to be in reasonable agreement with the predictions of this formula, its use has been limited.