Sadjad Hadei - Ph.D. Candidate, Department of Civil Engineering, Sharif University of Technology, Tehran, Iran
Mohammad M. Ahmadi - Professor, Department of Civil Engineering, Sharif University of Technology, Tehran, Iran

The behavior of piles under seismic loading is a complex soil-pile-structure interaction which its evaluation may be a very important issue in geotechnical design of piles. Earthquake can cause lateral loads on piles. These loads can be attributed to both kinematic interactions between soil and piles and to inertial interactions between superstructure and piles. Some investigations have been carried out to study the soil-pile-structure interaction, but most of these studies are limited to two-dimensional behavior, and are mainly focused on the superstructure response. The purpose of this paper is to study the three-dimensional dynamic response of piles in soil-pile-structure system using explicit scheme finite difference program, FLAC3D software. In this paper, in the framework of a set of fully nonlinear 3D numerical analyses in time domain a group of 3×3 piles embedded in cohesive soil is analyzed under the action of seismic loading, and the behavior of pile group is investigated in the absence as well as the presence of a superstructure. The results of this study clearly demonstrate the influence of mass of superstructure and soil stiffness on bending moments induced in the pilegroup subjected to seismic loading.

Dynamic response, Pile group, Soil-pile-structure interaction, Three-dimensional modeling, Mass of superstructure