An application of fuzzy fault tree analysis for spread mooring systems.pdf

Ocean Engineering 38 (2011) 285–294Contents lists available at ScienceDirectOcean Engineering0029-80 doi:10.1 n Corr E-m ismailh 1 Tejournal homepage: /locate/oceanengAn application of fuzzy fault tree analysis for spread mooring systemsAyhan Mentes n, Ismail H. Helvacioglu 1 Istanbul Technical University, Faculty of Naval Architecture and Ocean Engineering, 34469 Maslak, Istanbul, Turkeya r t i c l e i n f o Article history: Received 17 August 2010 Accepted 8 November 2010Editor-in-Chief: A.I. Incecik the spread mooring configurations. In conventional fault tree analysis (FTA), which is an established technique in hazard identification, the ambiguous and imprecise events such as human errors cannot be Available online 24 November 2010 Keywords: Spread mooring system Fault tree analysis Fuzzy fault tree analysis Risk assessment Fuzzy weighted index Fuzzy set theory18/$ - see front matter 2010 Elsevier Ltd. A 016/j.oceaneng.2010.11.003 esponding author. Tel.: +90 212 285 6393; fa ail addresses: mentes@.tr (A. Mentes), @.tr (I.H. Helvacioglu). l.: +90 212 285 6391; fax: +90 212 285 6454a b s t r a c t In this paper, a fuzzy fault tree analysis methodology for spread mooring systems is presented. The methodology combines the effects of operational failures and human errors under fuzzy environment for handled efficiently. In addition to this, the tolerances of the probability values of hazards are not taken into account. Moreover, it is difficult to have an exact estimation of the failure rates of the system components or the probability of the occurrence of undesired events due to the lack of sufficient data. To overcome these disadvantages, a fault tree analysis based on the fuzzy set theory is proposed and applied to the spread mooring system alternatives. Furthermore, sensitivity analysis is carried out based on the fuzzy weighted index (FWI) in order to measure the impact of each basic event on the top event. The results show that the fuzzy fault tree risk analysi