Seismic Reliability Assessment of RC Frame in a High Seismic Zone of India

Abstract

Uncertainties are common everywhere in day-today life. Deterministic approach will not be suitable always, in such cases Probabilistic approach yields better results. Characterizing the probabilistic nature of structural parameters can be done through the use of ‘Fragility Curves’. A fragility analysis assesses the probability that the seismic demand placed on the structure exceeds the capacity conditioned on a chosen Intensity Measure (IM), representative of the seismic loading. Demand (D) and capacity (C) are assumed to follow a lognormal distribution, and the probability of exceeding a specific damage state for a particular component can be estimated with the standard normal cumulative distribution function. In the present Study, Darjeeling region hazard Curves is chosen which is one of the most vulnerable zones in India. Hazard curve is the annual frequency of motion intensity at or above a given intensity level. It is expressed in complimentary cumulative distribution function (CCDF). Reliability assessment of RC structures is carried out by combining Fragility curve and Hazard curve. It is found that a building designed as per Indian code failed to achieve the Target Reliability. Although the present study ignored the contribution of infill walls, the building failed to achieve the target as the expected PGA corresponding to the target reliability is much higher that the design PGA.