Abstract
Past oscillator tests of soil-foundation systems in Japan are investigated from 22 repors, and relationships between damping values of the soil (or rock) and non-dimensional frequencies are obtained, namely 52 data for horizontal direction of the exciting force and 20 data for vertical direction of the exciting force. Non-dimensional frequencies are calculated from the equivalent shear wave velocity of the soil by the oscillator test. It is assumed that the natural frequency of soil-foundation systems by the experiment agrees with one by the theory on Dynamical Ground Compliance (DGC). Damping values of the soil in the case of horizontal and rotational excitation are calculated from those of soil-foundation systems in horizontal direction of exciting force. Three kinds of relationships between damping values of the soil and non-dimensional frequencies in the case of horizontal, rotational and vertical excitation are obtained and compared with theoretical damping values. Theoretical damping values are given by-f_<i2>/(2・f_<i1>) ratios of real part "f_<i1>" and imaginary part "f_<i2>" on DGC (i=H, R, V), namely on a semi-infinite elastic medium, on a semi-infinite viscoelastic medium and on a semi-infinite five layered medium. Experimental damping values of the soil are smaller than theoretical those from DGC on a semi-infinite elastic medium. The main reason is due to the site condition on a multi-layered medium. Considering in relation to the site condition on a multi-layered medium, in this paper dampimg values of the soil in design are proposed.
