Dynamic Stiffness and Seismic Response of Sleeved Piles

摘要

An axisymmetric finite element formulation with a consistent transmitting boundary is used to obtain dynamic stiffnesses and seismic response of sleeved piles in linear viscoelastic soil media. A sleeved pile consists of a column within a sleeve of substantially larger diameter which is filled with concrete to some depth below grade level. Recent research on the behavior of pile-foundations under dynamic loads has been stimulated by dynamic behavior studies which have disclosed that the effects study: a finite element formulation with a consistent transmitting boundary to stimulate the soil medium encircling the pile, and an approximate analytical method based on the concept of a generalized Winkler medium. Form the approximate analytical method, closed-form expressions were derived for the dynamic stiffness of the piles. Comparison of the results of the analytical and the finite element formulation methods showed that the analytical method, together with the appropriate subgrade moduli also obtained in this study, provide fairly accurate results for dynamic stiffnesses at low as well as at high frequencies.