Seismic fragility assessment for a RC building in seismically stable Brazil: A sensitivity analysis

Abstract

While Brazil is located in a markedly seismically stable region, most buildings are designed with little to no consideration for seismic activity. For this reason, a thorough investigation of building fragility is a requisite for precise risk estimates. However, some constraints currently affect broad seismic fragility assessments in the country, causing inherent uncertainties in different steps of fragility estimation. This paper focuses on comparing how different variables stemming from such uncertainties may affect seismic fragility, in order to evaluate which may be more important for future assessments. Herein, a low-rise, open ground, reinforced concrete building is evaluated, and the following variables’ sensitivity to the fragility response are compared: ground motion record selection; intensity measure (IM) selection; structural model parameter values; failure mode and limit state capacity. A cloud-based approach is used, employing a surrogate demand model for non-collapse data and a Logistic model for the inclusion of collapse data. The sensibility analysis results indicate that, for this assessment, failure mode variability due to detailing practices may cause the largest global impact on fragility variability, with a greater effect on intermediate intensity values. On the other hand, column backbone parameter uncertainty can be the most important factor on some of the smaller intensity values, while record selection influence, conditioned on the number of records used and on IM sufficiency, can have a smaller impact than the other variables.