As more and more emphasis is being laid on nonlinear analysis of Reinforced Concrete (RC)-framed structures subjected to earthquake excitation, the research and development on both nonlinear static (pushover) analysis as well as nonlinear dynamic (time history) analysis are in the forefront. Due to prohibitive computational time and efforts required to perform a complete nonlinear dynamic analysis, researchers and designers all over the world are showing keen interest in nonlinear static pushover analysis. The paper presents the overview of seismic provisions in Indian seismic codes published by the Bureau of Indian Standards with regard to seismic analysis and design. Since the country lies in earthquake-prone area and many of the past earthquakes have high number of casualties due to collapse of buildings and dwellings, an attempt has been made to present the complete details of methodology in a probabilistic manner to assess the seismic risk of RC buildings based on pushover analysis due to nonexistence/availability of code practices in the Indian context. Thus, the format may be used as a guideline for seismic risk analysis.

India has experienced destructive earthquakes throughout its history. Most notable events of major earthquakes in India are the ones in Kutch, Gujarat in 1819 and Bhuj, Gujarat in 2001. In many respects, including seismological and geotechnical, the January 26, 2001 earthquake was a case of history repeating itself after 182 years, which made the engineering community in India aware of the need for seismic evaluation and retrofitting of existing structures. Bhuj earthquake of January 26, 2001 caused 14,000 casualties. The main reason for such huge casualties is low earthquake awareness and poor construction practices. Based on technology advancement and the knowledge gained after earthquake occurrences, the seismic code is usually revised. The last revision of IS: 1893 (criteria for earthquake resistant design of structures) was done in 2002 after a long gap of about 18 years. Some new clauses were included and some old provisions were updated, assuming that concerned authorities will take enough steps for code compliance and the structures that are being constructed are earthquake-resistant.

Assessing the capacity of existing building as per the present codes of practice is an important task in the performance-based evaluation. In order to enhance the performance of existing buildings to the present level of ductile design prescribed by the present codes and find the retrofit or design of a rehabilitation system, there is an urgent need to assess accurately the actual lateral load resistance and the potential failure modes. The nonlinear static analysis (pushover analysis) gives better understanding and more accurate seismic evaluation of buildings as the progression of damage and failure can be traced. A compressive study of vulnerability of buildings and structures to various earthquake intensities has not been conducted in a systemic way in the country (India) so far (Anand, 2000). Hence seismic performance evaluation is a crying need in the Indian context, which is a prerequisite/precursor to retrofitting.

Structural Engineering Journal, Probabilistic Risk Analysis (PRA), Reinforced Concrete (RC), Nonlinear static analysis/Pushover analysis, RC building, Performance criteria, Uncertainty, Reliability, Fragility analysis.