STOCHASTIC CHARACTERISTIC OF SITE AMPLIFICATION FACTOR AND ITS EFFECT ON EARTHQUAKE GROUND MOTION

摘要

Evaluation of the variations of the design earthquake ground motion is very important, because the safety margins shall be set according to the variations of design variables in the earthquake resistant design. Earthquake ground notion is expressed by the multiplication of source characteristic, path characteristic and site amplification characteristic in the frequency domain. Although the source and path characteristics can be evaluated analytically, site amplification characteristic can only be evaluated precisely in an empirical manner by using the strong motion record because site amplification characteristic is strongly affected by the sedimentary environment of soil layers at the site of interest. Little study on the stochastic characteristic of site amplification factor has been done so far. In this paper, the authors evaluated the stochastic characteristic of site amplification factor by the spectral analysis on the strong motion records observed at two sites: reference site and target site. Variation of the representative value of earthquake ground motion such as peak ground acceleration and peak ground velocity considering the variation of site amplification factor is discussed.