Contact pressure and stress distribution

To understand the effects of stiffness of the soil and stiffness of the foundation on the variation of contact pressures beneath a uniformly loaded area and an area loaded by a point load. To appreciate the assumptions made when using stress distribution methods. To be able to determine the stresses beneath uniformly loaded areas of flexible and rigid characteristics and of a variety of shapes. To apply the stress distribution methods to determine amounts of settlement using the methods described in Chapter 9. A foundation is the interface between a structural load and the ground. The stress q applied by a structure to a foundation is often assumed to be uniform. The actual pressure then applied by the foundation to the soil is a reaction, called the contact pressure p and its distribution beneath the foundation may be far from uniform. The effects of the stiffness of the foundation (flexible or rigid) and the compressibility of the soil (clay or sand) are illustrated in Figure 5.1.