Fig 1.
The membership functions of the IT2FSs.
Fig 2.
Interval type 2 trapezoid fuzzy membership functions.
(a: related to opinion b: related to confidence).
Table 1.
Linguistic terms and their corresponding IT2FSs [51].
Fig 3.
Work flow diagram of proposed method.
Fig 4.
The link between barriers and how they affect the consequences based on the SHIPP theory.
Table 2.
Weighting scores of various experts [66].
Table 3.
Calculation weighting factors for 20 experts.
Fig 5.
Fault tree of gas release in spherical tank.
Table 4.
The basic events of fault tree and their symbols.
Fig 6.
Fault tree of release prevention barrier (RPB) failure.
Fig 7.
Fault tree of dispersion prevention barrier (DPB) failure.
Fig 8.
Fault tree of ignition prevention barrier (IPB) failure.
Fig 9.
Fault tree of escalation prevention barrier (EPB) failure.
Fig 10.
Fault tree of human factor barrier (HFB) failure and management &organizational barrier(M&OB) failure.
Table 5.
The symbols and descriptions of basic event of barriers’ failure fault tree.
Table 6.
FPS and FFP values of the basic events of the top event fault tree based on IT2FS-Z.
Table 7.
FPS and FFP values of the basic events of the top event fault tree based on IT2FS.
Table 8.
FPS and FFP values of the basic events in the barrier failure fault tree based on IT2FS-Z.
Table 9.
FPS and FFP values of the basic events in the barrier failure fault tree based on IT2FS.
Fig 11.
Comparison between probability of BEs calculated using IT2FS-Z and IT2FS in FTA.
Fig 12.
Comparison between probability of BEs calculated using IT2FS-Z and IT2FS in ETA.
Fig 13.
BN mapping from bow-tie (“a” is fault tree side of bowtie. “b” is event tree side with fault trees of barriers failure).
Fig 14.
a: Prior probability of barrier failure. b: Prior probability of consequences.
Table 10.
Prior and probability of barriers failure and consequences based on BN.
Fig 15.
a: Tornado graph displaying the top fifteen CBEs in the IT2FS-Z BN. b: Tornado graph displaying the top fifteen CBEs in the IT2FS BN.
Table 11.
Five-year cumulative table of CBE-related failures and successes.
Table 12.
The posterior probability of CBEs over the FIVE years.
Table 13.
The posterior probability of barriers failure based on beta distribution and BN.
Table 14.
The posterior probability of consequences based on beta distribution and Bayesian network.
Fig 16.
The prior and the posterior probability of the CBEs.
(a: IT2FS. b: IT2FS-Z).
Fig 17.
The posterior probability of barriers failure.
(A: RPB. B: DPB. C: IPB. D: EPB).
Fig 18.
The posterior probability of consequences.
(A: Near miss. B: mishap. C: Incident. D: Accident).
Fig 19.
The posterior probability of the consequences in different calculations, except for IT2FS(VAR = 10−4) (A: Near miss. B: mishap. C: Incident. D: Accident).