Dynamic lateral response of single piles considering soil inertia contribution

The most widely used model to perform the analysis of piles under lateral loads consists in modeling the pile as a series of beam elements and representing the soil as a group of unconnected, concentrated springs perpendicular to the pile (Discrete Winkler Model). The literature review shows that the soil stiffness and damping properties are included in a dynamic analysis through lumped springs and dashpots, but a lumped mass to represent soil inertia is not included.; The objective of this investigation is to perform an analytical and numerical study of the dynamic response of the pile-soil system under lateral loads (considering the soil as a semi-infinite half space), in order to develop a rational method that includes the soil contribution to the system inertial properties through a series of lumped masses, consistent with the Discrete Winkler Model, and to evaluate the importance of such lumped mass in the system response.; A simplified lumped model, consistent with the Winkler hypothesis, was obtained by performing an approximation of the continuous (plane strain) model developed by Novak. In the proposed approach, the pile-soil interaction is taken into account through three frequency independent elements: a spring with stiffness ka, a mass with value ma, and a dashpot with coefficient c a. The spring-mass-dashpot coefficients ka, ma, and ca that represent the soil can be obtained by means of simple equations.; The proposed lumped model was used to demonstrate that a lumped soil mass is not required for small soil Poisson's ratios. However, the soil mass is important for high soil Poisson's ratios, as may be the case of saturated soils (for nu = 0.5 the required soil lumped mass is in the same order of the pile mass contribution).