Development of Elastic Spectrum for Indian Context

Abstract

Response spectrum is a central and widely accepted concept in earthquake engineering to estimate lateral force on the structure. It is an envelope of maximum response of various Single Degree of Freedom (SDOF) systems to a specified earthquake ground excitation. The response spectrum can’t be used uniformly to design any structure since it is very much ground motion dependent. Apart, it is very much jagged in nature and required to be smoothen out. In order to utilize them for designing the structure uniformly it is converted to Elastic Design Spectrum. Elastic design spectrum is a by enlarge derived from response spectrums of ensembles of earthquake ground motions. The elastic design spectrum can be readily used for designing new as well assessing existing structure for seismic capacity. The elastic design spectrum is globally used to determine lateral force due to earthquake in seismic code of most of the countries. In the present paper, elastic design spectrum is developed for Indian subcontinent. About 184 earthquake ground motion records are compiled. Out of this 67 earthquake ground motions are established as Strong Ground Motion records to develop response spectrum. The response spectrums are converted to elastic spectrum through statistical analysis. Mean response spectra for East and North regions are very much similar to each other, while mean response spectra for West and South-East regions are similar. East and North region has wide velocity sensitive region as compared to West and South-East regions.