Radius of Relative Stiffness (Westergaard)
According to Westergaard, the relative stiffness of the concrete slab and its subgrade is defined in the equation shown. It is called the Radius of Relative Stiffness. It has a linear dimension and depends on the properties of the slab and the foundation.
The Radius of Relative Stiffness appears in many equations involving stresses and deformations in concrete pavements.
Theoretical Foundation
l = Relative Stiffness Radius (in)
E = Pavement Elasticity Modulus (psi)
h = Pavement Thickness (in)
µ = Pavement Poisson's Ratio
k = Subgrade Reaction Modulus (pci)
