Abstract
The aim of this study is to investigate experimentally the vibration properties of rigid body placed on dense sand ground surface. The rigid body with variable mass, inertial moment and base size was prepared, and its vibration behavior was observed in a series of free vibration tests. From the observed behaviors the natural vibration period, critical damping factor and vibration mode were analyzed. It was found that the natural vibration period is dependent not only on the mechanical properties of footing and foundation ground, but also on the vibration amplitude. This suggested the notable effect of nonlinear strain dependent stiffness of ground material on the vibration properties of the body underlined. The stiffness coefficients of springs modeling the interactive mechanical behavior between rigid body and ground, were assessed from the observed behaviors based on the modal analysis. The influence of base pressure and basesize on the spring coefficients is discussed.
