Performance Based Design: Case Study

Earthquakes are inevitable in many parts of the world. The existing research on Indian subcontinent shows that more than 60% of the country's land is vulnerable to all kinds of earthquakes. Past experience with earthquakes and the eventual damage to the structures suggests that the seismic risk in urban areas is more and the infrastructure facility is far from socio-economically acceptable levels. It is an evident fact that these earthquakes caused large destruction to the infrastructure and buildings in the past. In this scenario, designing an earthquake resistant building/structure is the greatest challenge for a design engineer. Designing a building for earthquake resistance according to the present standard code of practice revealed its insufficiency in providing complete resistance during earthquakes. Performance based design, comparatively a new technology over strength based design suggested in standard Indian code, is a design procedure followed to achieve realistic behavior of the building/structure and eventually resulting in a reliably accurate earthquake resistant design. The performance based design utilizes “static nonlinear pushover analysis” as a tool to estimate the nonlinear capacity of the building/structure.

In the present study, an attempt is made to understand the procedure and methodology adopted in performance based design and its implications to achieve an earthquake resistant design. A G+4 storey commercial building, assumed to be situated in seismic zone IV (according to IS: 1893(part1)-2002), is considered for the case study. Static nonlinear pushover analysis is performed to estimate the capacity of the building represented in the form of a pushover curve. Five performance levels, based on the criteria for earthquake resistant design, are defined for the building. The hinge mechanism obtained in each step of the pushover, is studied to obtain a desired performance level.