Design of Base Isolation System for Buildings

Introduction And Background

Past earthquakes have indicated, especially in developing countries, that major loss of life often occurs due to the collapse of poorly constructed buildings. If the level of seismic demand on these buildings is reduced through a simple but reliable engineering solution, this would result in much safer design. Seismic base isolation, which is aimed at reducing the seismic demand instead of increasing the earthquake-resistant capacity of the structure, is an attractive alternative to conventional earthquake-resistant design methods. Seismic base isolation is one of the most widely implemented and accepted seismic protection systems. Seismic isolation is a relatively recent and evolving technology. It has seen an up-rise in use since 1980s, and has been well evaluated and reviewed internationally. The two most common types of base isolation systems adopted in practice utilize either rubber bearings or sliding systems between the foundation and superstructure for the purpose of isolation from ground motions in the buildings as well as bridges. Base isolation has now been used in numerous buildings in countries like Italy, Japan, New Zealand, and USA. Base isolation is also useful for retrofitting of important buildings (like hospitals and historic buildings). By now, over 1000 buildings across the world have been equipped with seismic base isolation. A four storey hospital building at Bhuj, India has been constructed using base isolation technique where the isolators were brought from New Zealand (Govardhan and Paul, 2016).