ABSTRACT
Paramount in the mind of the engineer is to make a safe design; secondly, and with nearly as much importance, is to have the design perform well without excessive cost. The following sections will direct attention to the many of factors that enter into the selection of pile dimensions. The engineer may be guided by codes and standards of a building authority; even so, the engineer is left with considerable latitude. For example, in evaluating the data from a subsurface investigation, a very conservative or a less conservative set of values could be selected. The global approach, where an overall factor is selected, is the usual method for the
selection of a safety factor. A more recent method, the component approach, is where separate factors are given to various properties required for the design. Both methods will be discussed in some detail. However, a number of topics will first be discussed that are common to both methods. Modern approaches to the design of pile foundations emphasize deformation as well
as ultimate capacity. Deformation of a pile or a group of piles is an important aspect of some of the methods presented, which parallels to some extent the procedures in this book. Examples are presented where successive solutions are made by incrementing the loading, nonlinear load transfer mechanisms are employed, and sometimes nonlinear pile material, and the load is found that causes collapse or excessive deformation. Such a procedure is valid, regardless of the method employed to select safety coefficients.
