Advanced soil-pile-structure interaction and nonlinear pile behavior

This dissertation is aimed at developing advanced formulations for the analysis of pile foundations subjected to various types of forces. The present work includes unification of past contributions of several researchers in the field of linear static and dynamic analysis and further development based on that framework. Obviously, the present research benefits from various features already available and the result is a versatile numerical tool for advanced analysis of pile foundations.; A linear formulation for dynamic analysis is presented in the frequency domain for both forced and seismic excitations. A major thrust of this analysis has been to study dynamic soil-pile-structure interaction by coupling the superstructure and piles to the soil. The soil is modeled as a multilayered continuum in a hybrid boundary element formulation. The structure and piles are modeled as elastic beam-column elements. Interaction effects and need for such a coupled analysis have been emphasized through numerical examples. Additionally, effects of local linear interface conditions are investigated.; In order to develop nonlinear dynamic analysis capabilities, the groundwork is laid by beginning with nonlinear static analysis. A formulation is presented for including the effects of nonlinear interface phenomenon such as pile-soil slip and gap formation. Under a lateral mode of deformation, nonlinearity of soil plays a dominant role and this is modeled in a rational way, by unifying the benefits of continuum based and 'localized' spring based approaches.; A time-domain formulation is then presented that incorporates nonlinear effects following the procedure of static analysis. The boundary element equations are formed by utilizing an approximate fundamental solution in a homogeneous halfspace. Results of linear time-domain analysis for single piles and groups are in very good agreement with the Laplace transform results.; Lastly, an approximate fundamental solution is synthesized for dynamic point force and source, buried in a homogeneous, isotropic poroelastic halfspace. Analysis of pile foundations in such media is formulated and numerical resuts presented. By implementing a Laplace transform domain algorithm, time-domain dynamic analysis is presented.; The dissertation concludes by summarizing the present work and recommending areas of future research.