Frequency-independent dynamic stiffness and damping of laterally loaded single piles

Abstract

A practical analytical model for the analysis of a pile subjected to lateral dynamic loads is presented. The model is based on the damped oscillator representation of a pile-soil system. The stiffness and damping were obtained by fitting the equation that governs the vibration of a damped oscillator to the dynamic displacements of the pile-soil system obtained by a three-dimensional finite element analysis. Unlike existing models, the model is frequency independent. Thus, the stiffness and damping can be used in the analysis of a soil-pile system in the time domain. The numerically obtained stiffness and damping are presented in dimensionless charts and influence factor Tables and can be used for analyses of massless piles and piles with added mass subjected to different loading conditions such as harmonic, impact, or earthquake loading. Time-domain analyses of piles that have been subjected to impact loading and earthquake motion are presented. Using the analytical model with the numerically obtained frequency-independent stiffness and damping compared well with existing models and with three dimensional finite element analyses results.