Fuzzy possibility-based safety assessment of portal steel frame

Abstract

This paper investigates the application of fuzzy possibility theory for assessing the safety of portal steel frames, addressing the limitations of traditional methods such as Load and Resistance Factor Design (LRFD) and Al- lowable Stress Design (ASD) in handling uncertainties and subjective judgments in structural systems. Portal steel frames, widely used in industrial buildings, are susceptible to various uncertainties in loads, material prop- erties, and geometric dimensions. Unlike probability theory, fuzzy possibility theory offers a robust framework for quantifying the possibility of safety or failure under imprecise or incomplete information, making it ideal for capturing real-world variability. The study establishes a practical procedure for structural fuzzy possibil- ity analysis. It further introduces a new fuzzy possibility degree model that accounts for the importance of information at different membership levels, enhancing the assessment of structural safety compared to exist- ing models. Numerical results demonstrate that the proposed model, operating within an extended possibility measure interval of (−1, 2), provides more refined and reasonable outcomes than traditional models confined to (0, 1), effectively distinguishing between absolute safety, absolute failure, and intermediate cases. Through a case study of a portal steel frame subjected to dead loads, live loads, wind loads, and foundation settlement, the paper evaluates safety and failure possibilities using deterministic and different fuzzy methods. Findings highlight the superiority of the proposed fuzzy possibilistic model in capturing complex uncertainties, though its non-traditional results require careful interpretation. Validating the model against empirical data, explor- ing sensitivity analyses, and developing normalization methods to bridge traditional and extended possibility frameworks, offer valuable insights for enhancing structural safety assessments in civil engineering.