M. Kasaeyan; J. Wang; I. Jenkinson; M. R. Miri Lavasani
Volume 1, Issue 1 , December 2011, , Pages 3-12
Abstract
The traditional event tree analysis uses a single probability to represent each top event. However, it is unrealistic to evaluate the occurrence of each event by using a crisp value without considering the inherent uncertainty and imprecision a state has. The fuzzy set theory is universally applied to ...
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The traditional event tree analysis uses a single probability to represent each top event. However, it is unrealistic to evaluate the occurrence of each event by using a crisp value without considering the inherent uncertainty and imprecision a state has. The fuzzy set theory is universally applied to deal with this kind of phenomena. The main purpose of this study is to construct an easy method to evaluate human errors and integrate them into event tree analysis by using fuzzy concepts. A systematic fuzzy event tree analysis algorithm is developed to evaluate the risk of a largescale system. A practical example in of offshore oil pipeline is used to demonstrate this procedure.
M. R. Miri Lavasani; J. Wang; Z. Yang; J. Finlay
Volume 1, Issue 1 , December 2011, , Pages 29-42
Abstract
Fault Tree Analysis (FTA) as a Probabilistic Risk Assessment (PRA) method is used to identify basic causes leading to an undesired event, to represent logical relation of these basic causes in leading to the event,
and finally to calculate the probability of occurrence of this event. To conduct a quantitative ...
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Fault Tree Analysis (FTA) as a Probabilistic Risk Assessment (PRA) method is used to identify basic causes leading to an undesired event, to represent logical relation of these basic causes in leading to the event,
and finally to calculate the probability of occurrence of this event. To conduct a quantitative FTA, one needs a fault tree along with failure data of the Basic Events (BEs). Sometimes it is difficult to have an exact estimation of the failure rates of individual components or the probabilities of occurrence of undesired events due to a lack of sufficient data. Furthermore, due to imprecision in failure data of BEs, the overall result may be questionable. To avoid such conditions, a fuzzy approach may be used with the FTA technique. This reduces the ambiguity and imprecision arising from the subjectivity of data. Traditional FTA method needs a sound data base of failure of all BEs for quantifying the probability failure of system, whilst there is not such a database available in offshore pipeline industry; therefore, fuzzy FTA approach is proposed to deal with this issue. The proposed model is able to quantify the fault tree of offshore pipeline system in the absence or existence of data. This paper also illustrates with a case study the use of importance measures in sensitivity analysis.