Dynamic analyses of a pile group embedded in a homogeneous soil are carried out by the advanced method in which the pile-soil-pile interaction effects are included by using the Green's function derived from the thin layer formulation. The effective input motions of a pile foundation are computed and the dynamic characteristics are studied from view points of the effects on the diameter of a pile, the pile space and the number of piles. As the results, it is understood that the magnitude of the input motions is reduced in the higher frequency range, and the redaction effect is significant as the diameter of a pile is increasing, the pile space is getting smaller and the number of piles is increasing. Furthermore, the earthquake response analysis of the 5-story building supported by 4 × 4 pile group is carried out, and the influence of the input loss due to the pile group is discussed by observing the maximum response values and the transfer functions of the building.
