Dynamic Axial Stiffness and Damping Parameters of Tapered Piles

Abstract

The theoretical models currently reported in the literature idealize a uniformly tapered pile as a step-tapered pile to facilitate dynamic analysis. The step-taper idealization produces approximate solutions, which become more accurate as the number of steps is increased. This paper presents a new theoretical model for obtaining axial stiffness and damping parameters of tapered piles. The underlying theory is consistent with the traditional elastic model for the vertical vibration of cylindrical piles. The governing differential equation for vertical vibration of a uniformly tapered pile is solved numerically using software, and the dynamic response is analyzed; it is observed that the resonant amplitude can be significantly reduced with an increased taper angle. A simple approximate solution is also presented, and the results are in good agreement with the numerical solution. Frequency-dependent axial stiffness and damping parameters of tapered piles can thus be obtained quickly and with sufficient accuracy by implementation of the proposed approximate method.