ATTENUATION RELATIONSHIP FOR SPECTRAL DISPLACEMENT FOR HIMALAYAN REGION

Abstract

Using selected sets of high quality digital strong motion data from different regions (Taiwan, Italy, Iran, Maxico, California) along with Indian region, the salient features of displacement response spectra in the long-period range are illustrated ( up to 10 second period) as a function of magnitude, source distance, and site conditions. The findings of this study are believed to be particularly useful in the formulation of design elastic displacement spectra for seismic codes, and in zoning studies of seismic hazard for long-period structures. For Indian region there is no attenuation relationship available for displacement spectra. In this report attenuation relationship for elastic displacement spectra for Indian region is proposed. For Indian region due to lack of sufficient strong motion data set which has low frequency content additional strong-motion data from world-wide earthquake have been included. Due to non availability of sufficient strong motion data set of Himalayan region required for development of displacement spectra some of the dataset of other country has been merged in order to remove the deficiency of spectra at longer period. Using carefully processing of Indian data set with other country dataset such as PEER, Iran, Japan, Italy strong motion data set the attenuation relationship for displacement spectra for Himalayan region have been derived for 5% damping and response period up to 10 seconds i.e., study deals with development spectra for longer period range. Effect of all parameters associated with displacement response spectrum such as earthquake magnitude, local geological condition of site, source to site distance and low-frequency content present in acceleration time history etc. has been studied. The parameters of low and high pass filters and their effect on the response spectra has been critically reviewed.