Seismic Risk Assessment of Reinforced Concrete Frame with Consideration of Aleatory and Epistemic Uncertainty

Abstract

A simplified method for seismic risk assessment with consideration of aleatory and epistemic uncertainties is applied to an example of a reinforced concrete frame structure. The fragility parameters that represent an intermediate result of the risk study are determined with a nonlinear static analysis of a set of structural models, which is defined by utilizing the Latin Hypercube Sampling technique, and nonlinear dynamic analyses of equivalent single-degree-offreedom (SDOF) models. The set of structural models captures the epistemic uncertainties, whereas the aleatory uncertainty due to the random nature of the ground motion is, as usual, simulated by a set of ground motion records. Although the method is very simple to implement, it goes beyond the widely used assumption of independent effects due to aleatory and epistemic uncertainty. Thus, epistemic uncertainty has a potential influence on both fragility parameters, and not only on dispersion, as has been assumed in some other approximate methods. In the case of the eight-storey frame it is shown that the epistemic uncertainties decreases the peak ground acceleration, which causes the near-collapse limit state. Consequently, the estimated near-collapse risk with consideration of both sources of uncertainty is significantly higher if compared to the risk determined only with consideration of the aleatory uncertainty.