EVALUATION OF DYNAMIC INTERACTION FACTOR OF RECTANGULAR PILED RAFT FOUNDATION FOR HORIZONTAL AND ROTATIONAL MOTION

The interaction between a building and the soil its foundation is built into is important in evaluating the seismic response of the building. The dynamic impedance of a piled raft foundation depends on a dynamic interaction factor between the raft and pile group. In this paper, numerical analyses were performed to investigate the frequency characteristics of the dynamic interaction factor of a rectangular piled raft foundation with various aspect ratios, subjected to a building inertial force caused by an earthquake. Based on the analytical results, a formula was proposed that considers the aspect ratio of the foundation in evaluatiing the dynamic interaction factor for a rectangular piled raft foundation. It was confirmed that the dynamic impedance calculated by a simplified calculation using the dynamic interaction factor and the dynamic impedances of a spread foundation and pile foundation, corresponds well with the results of the numerical analysis.