Seismic Risk Management for Critical Infrastructures Using an RMIR Indicator

Recent earthquake events have highlighted the importance of critical infrastructures (CI) resilience, as a strong correlation was found between the economic loss and the severity of CIs damage. CIs are characterized by a complex structure composed of sub-components that are essential for the continuous performance of the system. CIs owners and governments allocate ample of their resources in retrofitting and upgrading CIs systems and components to increase the resilience of CIs and reduce the risk they are exposed to in case of seismic events. Governments and decision-makers must manage and optimize the retrofit efforts to meet the budget and time constraints. This research presents a probabilistic methodology for seismic risk mitigation and management in CIs. The risk expectancy is appraised according to an FTA-based simulation. The simulation includes the development of exclusive fragility curves for the CI and an examination of the expected damage distribution as a function of the earthquake intensity. Furthermore, this research proposes a novel RMIR (Risk Mitigation to Investment Ratio) indicator for priority setting of seismic mitigation alternatives. The RMIR is a quantitative indicator that evaluates each alternative's cost-effectiveness in terms of risk expectancy mitigation. Following the alternative's RMIR value, it is possible to prioritize the alternatives meeting the budget and time constraints. This paper presents the implementation of the proposed methodology through a case study of a generic pumping station. The case study includes twelve mitigation alternatives examined and evaluated according to the RMIR indicator.