Determination of first mode ground period and site-dependent design response spectrum for Taiwan High Speed Rail

The objective of this paper is to identify the first mode ground period T-g, at each interesting site along Taiwan High Speed Rail (THSR) route, and further, to determine the site-dependent design response spectrum for particular sites with T-g larger than 1 s. In this paper, a linear model of shear wave propagating in a multi-layered half-space is developed to identify the first mode ground period T-g of an interesting site on the basis of the field bore hole data. Furthermore, for each one of the strong ground motion observation stations within the Chiayi-Tainan area, the first mode ground period Tg was identified by either coda waves or pre-event ambient vibrations from the seismograms. In addition, the site-specific parameter C-v in defining the normalized response spectrum was also determined based on the observed strong ground motions at the specified observation station, and hence the empirical function between T-g and C-v can be regressed for this interesting area. Therefore, for a particular site along THSR route within the Chiayi-Tainan area, the site-specific parameter C-v can be determined from the regressed empirical function by the identified first mode ground period T-g, and further, used to develop the site-dependent design response spectrum. (C) 2004 Elsevier Ltd. All rights reserved.