Design of Earthquake Resistant Building Using Site Specific Response Spectra

Abstract

The energy released due to earthquake as seismic wave is propagated from the epicentre to the earth surface. This seismic wave causes the ground shaking which in turn causes severe damages to the structure overlying on the surface. During the propagation of this wave it has to travel through rock and soil types having different properties and of variable depth. According to the Indian standard for Earthquake resistant design (IS: 1893), the seismic force depends on the zone factor (Z) and the average response acceleration coefficient (Sa/g) of the soil types at thirty meter depth with suitable modification depending upon the depth of foundation. As per IS 1893, only three types of soils (soft, medium and hard) is considered without any consideration for the site specific soil parameters. In the present study an attempt has been made to generate response spectra using site specific soil parameters for some sites in seismic zone V, i.e. Arunachal Pradesh and Meghalaya and the generated response spectra is used to analyze some structures using commercial software STAAD Pro. The effect of soil properties, its types and the depth of soil in the response spectrum is discussed using Educational Version of the Oasys Siren software. The response spectrum is obtained from Siren 8.2 in which the physical properties and time history data of an earthquake i.e. North-East earthquake of September 10, 1986 which had the magnitude of 5.2 is considered. Finally comparisons have been made in between the structure designed by taking IS 1893:2002 response spectra under consideration with the structure designed by considering the generated response spectra for various types of soil for the seismic zone in terms of bending moment, shear forces and reinforcement.