ABSTRACT
The objective of this chapter is to develop a procedure for computing the movement of a cap for a group of piles when subjected to axial load, lateral load, and overturning moment. Several elements of the procedure must be addressed. The mechanics must be addressed, taking into account the nonlinear deflection of each pile head, for both vertical and battered (raked) piles, due to the imposition of an axial load, a lateral load, and a moment. The mechanics of the problem are discussed first. A brief review is given of some
of the relevant literature, and a set of equilibrium equations is presented that can be solved by iteration. A framework is established for the input of the nonlinear response of individual piles. A brief reference is made to the response of individual piles under lateral loading.
The early chapters of the text address lateral loading in some detail. A computer code (subroutine) for individual piles under lateral loading can readily be attached to a global program on pile groups if the influence of close spacing can be explicitly defined. A review is made of technical literature concerning the deformation of individual
piles under axial load. While the objective of the book relates principally to lateral loading, the load versus deflection for axially loaded piles must be addressed. If the cap for a pile group is subjected to an inclined and eccentric load, some of the piles in the group certainly must sustain an axial force. Thus, nonlinear relationships must be selected to define axial load versus deflection for a variety of kinds and sizes of piles. If piles under lateral loading are spaced close to each other, the piles will influence
each other due to pile-soil-pile interaction. The interaction of closely spaced piles under lateral loading is discussed in detail and recommendations are given for modifying the p-y curves to account for close spacing. Close spacing of piles under axial loading must also be addressed as is piles under
lateral loading. The problem of pile-soil-pile interaction for axial loading is discussed and recommendations are made for formulating influence coefficients to account for close spacing. Finally, a comprehensive study is analyzed where a pile group, including batter
piles, was subjected to inclined and eccentric loading. The computed values of pile-cap
movements were compared with values obtained from experiment. A computer code, based on the computed response of individual piles and on the mechanics noted above, yielded results that agreed well with the experimental values.
