Uncertainty assessment of improved multistate reliability in the sociotechnical systems based on the polymorphic fuzzy entropy fault tree analysis and triptych cost-benefit-safety analysis

Abstract

The firewater system is a critical system related to the fire safety process of the LPG storage tanks. However, installing an effective firewater system can control fire accidents. Therefore, the multistate reliability of the firewater system must be evaluated and uncertainties must be taken into account to improve the firewater systems and provide fire safety measures in the sociotechnical systems. However, obtaining multistate failure probability (MFP) data for basic events in polymorphic fuzzy fault tree analysis (PFFTA) has always been a major challenge. Quantifying the minimum cut set (MCS) in PFFTA and determining the critical components for improving the multistate reliability is also difficult. In this study, we propose the polymorphic entropy fault tree analysis (FTA) using the similarity aggregation method (SAM) and a Pythagorean fuzzy cost-benefit–safety analysis. In the proposed methodology, the entropy method was used to judgment expert evaluate the weight experts. The similarity aggregation method was used to aggregate of experts’ opinions and assess the multistate failure probability of basic events in the PFFTA. As a result, a triptych cost-benefit–safety analysis based on Pythagorean fuzzy sets (PFSs) was estimated to reduce expert subjectivity and support an improved cost-effectiveness index to rank critical components. To clarify the effectiveness and feasibility of the proposed methodology, a case study of the firewater system related to LPG storage was demonstrated. Both evaluations of the cost-benefit-safety analysis of the critical component were performed and improved the multistate reliability of the firewater systems.