Abstract
The vibrational behaviour of footing excited on soil is characterized by the "dissipation damping" which is named for that caused by radiation of vibrational energy to infinitely extending soil. The paper shows, at first, simplified expressions of propagation of seismic waves caused by a point excitation on the surface of a semi-infinite isotropic medium, and next, using those expressions, derives the solutions of vibrations of rectangular footing as well as circular footing under the assumption of the stress distribution of Boussinesq. The modes of vibrations include the vertical, horizontal and rotational motion. Some numerical results are illustrated for the comparison of those already obtained only for circular footing by the different methods. The more quantitative data relating to frequency and damping will be presented in the following paper.
