关键词: 场地, 持时, 包络线, 反应谱比值

Abstract: According to the epicenter distance and the site classification, the 404 groups of earthquake recordings of the main shock of Chi-Chi, Taiwan, China earthquake in 1999 are sorted out in this paper. Based on these data, we analyze the statistic features of duration, PGA, envelopes and response spectra ratio of horizontal and vertical component of the acceleration recordings. The results of analyses show that the effect of site classification on characteristics of various components in acceleration time history is obvious; furthermore, fault direction also has certain effects on the characteristics of horizontal component of ground motion acceleration. The detailed research results are: 1) the duration of horizontal component of acceleration records increases with the softening of site; 2) the direction of fault slip has some effects on PGA’s attenuation features; 3) the average envelopes of acceleration records at different distances and site class basically are single peak functions of time and the envelopes of horizontal and vertical components of ground motion are obviously different; 4) with the same epicenter distance, EW/SN response spectrum ratios tend to approximate to 1.0 as site becomes softer and period shorter. V/H response spectrum ratios in short periods (<0.1s) increase with the softening of site, however, V/H ratios within long-period range (>characteristic period) decrease with the softening of site, and the decrease of V/EW ratio speeds up relatively.

Key words: site, duration, envelope, response spectrum ratio