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

Abstract

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.