Abstract: A simple analytical solution was outlined for computing the lateral dynamic impedance of single floating piles and floating pile groups in layered soil media.A dynamic Winkler model utilizing the finite-element-based springs and dashpots was adopted for the effect of pile-soil interaction,combining with a transfer-matrix formulation in the case of multi-layered soils.Attention was then given to the lateral dynamic stiffness and damping of group piles.Pile-soil-pile interaction was considered by assuming interaction between the passive piles and the surrounding soil.It was demonstrated that the predicted result of the proposed simplified method was in good agreement with rigorous numerical solutions.Such a simplified approach was quite efficient for the computation of single piles and pile groups subjected to lateral vibration,and provided a useful tool for engineers due to its simplicity.