Damping modification factors observed from the indian strong-motion database

Abstract

A total of 203 horizontal acceleration time histories recorded between 1986 and 2001 are taken from the Indian strong-motion database and their response spectra for different damping ratios are analyzed, statistically. The observed damping modification factors are compared with those available in scientific literature and national seismic design codes. Contrary to the recommendations of various seismic design codes, as observed by some past researchers as well, the damping modification factors are found to be dependent on the spectral period. Simplified empirical expressions are provided to compute the damping modification factors while accounting for the effects of spectral period and damping ratio.