Date of Award


Degree Type


Degree Name

Doctor of Philosophy


The determination of stiffness and damping of piles is an important step in the analysis of pile-supported structures subjected to dynamic loading.;The first part of this study examines the use of approximate methods to evaluate the impedance functions of single piles and pile groups. The group impedances derived from the superposition of the two-pile solution are compared with those obtained from direct analysis. Good agreement is observed for floating piles in homogeneous and nonhomogeneous soil profiles. An extensive set of dynamic pile-soil-pile interaction factors is presented in a form suitable for interpolation. An approximate approach for the evaluation of pile-group impedances is proposed. The approach is based on combining the single-pile solution with curve-fitted expressions of the interaction factors.;In the second part of the study, field experiments are conducted to evaluate the response of a single pile and a pile group to harmonic loading. The experimental results are compared to the theoretical predictions of the linear theory. The comparisons indicate that the theory provides a good estimate of the single-pile and pile-group stiffness. However, the damping is significantly overestimated.;The third part of the study investigates the effects of separation and slippage at the pile-soil interface on the stiffness and damping parameters. A semi-analytical frequency-domain analysis and a time-domain boundary-element formulation are presented. Approximate corrections to the linear theory are suggested in order to include the effect of confining pressure and displacement amplitude on response predictions.



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