Seismic risk assessment for steel framed buildings

Abstract

The objective of this study is to propose, develop, and apply an approach to determine the expected seismic loss and probability of exceeding the loss (i.e., seismic risk) for steel framed buildings. The proposed framework uses models for seismic hazards, structural fragility, and loss functions to estimate the system-wide costs owing to earthquake retrofitting and recovery. The approach is further illustrated by examples of six- and 20-story steel buildings. The buildings have three kinds of lateral load resisting systems, including moment-resisting frames, eccentrically braced frames, and buckling-restrained braced frames. The structural design of the buildings satisfies code requirements and the details reflect the common practices adopted in Taiwan. The state-of-the-art in earthquake engineering is shifting from uniform hazard design to uniform risk design. The sample buildings were used to evaluate the design with uniform hazard spectra. The risk level of collapse was found to increase for low-rise buildings and for braced frames. The result suggests that the code-compliant design cannot guarantee that buildings have the same collapse risk. More studies and new codes are needed to design steel framed buildings with uniform risk.