Development of Seismic Design Spectra For Shallow and Deep Soil Sites Considering Region Specific Parameters

Abstract

Earthquakes are among the deadliest in all the natural disasters and have affected many people in the last few decades. The efforts to reduce or mitigate the impact of earthquakes have become increasingly focused upon in both developed and developing countries. Theory of plate tectonics and Engineering Seismology have helped to understand the physics of earthquakes and predict the hazards associated with it. Even after the improvement in building codes and level of preparedness, the mortality rate is alarming in the developing counties like India. However, until today the regional scale hazard mapping in terms of return period has been not fully implemented in India. In India, urban centres and cities are more susceptible to high earthquake hazard due to high population density, improper planning, poor land use and substandard construction practices. The first and foremost step to reduce earthquake disaster is to develop the seismic hazard map and arrive at design parameters at the surface due to the presence of deep and shallow soil deposits. The primary objective of the present study is to develop a new design response spectrum for the deep and shallow soil sites of the Indian subcontinent with seismic site classification considering regional parameters. To achieve the objective, the study is divided into four major parts and presented as contributing chapters in this thesis. A significant variation of design spectral values has been observed in four different seismic ground motion bins in shallow and deep soil sites. Design spectrum that accounts soil amplification at shallow and deep sites and seismicity variation in SI and the Himalayan region has been developed for the first time in this study. These spectra may be considered as a replacement of IS 1893 design spectrum, which does not account variation in seismicity and amplification due to shallow and deep soil sites in India.