American Concrete Pavement Association
The Radius of Relative Stiffness (the stiffness of the concrete slab relative to that of the foundation on which it rests) is commonly used in structural design of pavements. This web applet, based on the equation derived by Harold Malcolm Westergaard, allows you to quickly determine the Radius of Relative Stiffness (l) based on the concrete’s modulus of elasticity and Poisson’s ratio, the slab thickness, and the k-Value of the subgrade/subbase system.
The user accepts ALL responsibility for decisions made as a result of the use of this design tool. American Concrete Pavement Association, its Officers, Board of Directors and Staff are absolved of any responsibility for any decisions made as a result of your use. Use of this design tool implies acceptance of the terms of use.