FOUNDATION DYNAMICS.

The methods of analysis presented deal with foundations at the surface of the earth. Analysis and design of foundations subject to dynamic loads are generally based on single- and multidegree-of-freedom lumped-parameter analogs derived from elastic half-space theory. Embedded foundations and pile foundations may be analyzed by treating them as if their bases are supported on an elastic half-space and their perimeters are surrounded by many thin elastic layers. Alternately, piles may be replaced by equivalent cantilevers for axial and bending loads, and then treated as single- or double-degree-of-freedom systems. High-amplitude earthquake-type excitation requires analysis by discrete-parameter multidegree-of-freedom systems or finite-element methods. Soil properties used in all methods of analysis must be carefully determined because they vary dramatically with shearing-strain amplitude.