Earthquake-Induced Collapse Risk and Loss Assessment of Steel Concentrically Braced Frames

This paper quantifies the collapse risk and earthquake-induced losses for a wide range of archetype buildings with special concentrically braced frames (SCBFs). The collapse risk and expected economic losses associated with repair, demolition and collapse are computed based on a performance-based earthquake engineering framework developed within the Pacific Earthquake Engineering Research Center. It is shown that the collapse risk of the steel SCBF archetypes may be significantly overestimated when the influence of the gravity framing system on the lateral frame strength and stiffness is ignored. It is also found that the building-specific earthquake loss assessment is significantly overestimated at low probability of occurrence seismic events (i.e., 2% probability of occurrence in 50 years) when the gravity framing system is not modeled explicitly as part of the nonlinear building model. For frequent and design-basis seismic events (i.e., 50 and 10% probability of exceedance over 50 years of building life expectancy), acceleration-sensitive nonstructural component repairs govern the building losses regardless of the employed nonlinear building model representation. For the same seismic events, steel brace flexural buckling contributes to structural repair losses.