“…The term derives from the fuzzy sets theory (Zadeh, 1965). In civil engineering, FSs are applied in problems that require analysis in presence of uncertainty: some noteworthy applications concern the structural design (Biondini et al, 2004; Malekly et al, 2009), structural reliability (Dordoni et al, 2010), structural control (Kim et al, 2010), risk analysis (Sadeghi et al, 2010), and the treatment of uncertainties (Möller et al, 2003; Sgambi, 2004; Baitsch and Hartmann, 2006; Tagherouit et al, 2011; Wang and Li, 2011).…”