SITE DEPENDENT RESPONSE SPECTRA FOR ASEISMIC DESIGN

Abstract

The present investigation primarily deals with the site dependent response spectra for aseismic design. Only two site conditions which are commonly available i.e. rock and alluvial have been considered. Prediction of a precise and exact response spectra at a site is very difficult due to variable nature of parameters involved. Therefore an average response spectra depending upon local soil conditions should be considered. In the present work an attempt has been made to work out such an average spectrum curve for rock and alluvial sites by the analysis of recorded earthquake data. Five criteria for normalisation of response spectra have been used and it is found that the response spectra corresponding to peak ground acceleration is most suitable. Therefore average response spectra with respect to this cri--teria are recommended for rock and alluvial sites for various damping values. Besides this, different formulae for peak ground acceleration have been critically studied and a new empirical relationship for peak ground acceleration has also been suggested for rock site.