# Risk Assessment of Lift-Jacking Accidents Using FFTA-FMEA
## 6 Conclusions  
The FFTA-FMEA theory is applied to establish the reliability analysis model of lift-jacking accidents and the feasibility of the built evaluation model is verified by using the real engineering example; the following conclusions are obtained:  
(1) FTA, fuzzy set theory, and aggregation method are combined in the analysis of the lift-jacking accidents to identify the causal factors from the qualitative perspective and determine the probability of failure from the quantitative perspective. The method overcomes the difficulties in obtaining the exact probability of causal factors of lift accidents in the traditional analysis method and reduces the subjectivity of human judgement in the expert judgement method.  
(2) The FFTA-FMEA method is developed to deeply, comprehensively, and accurately characterise risk magnitude in actual operation and maintenance processes, enabling managers to promptly strengthen supervision based on assessment outcomes. This approach facilitates a more overall and useful assessment of risk and enhances management decisions.  
(3) Empirical case demonstrates the usability and effectiveness of the method. The case identified severe wear of traction sheave grooves, oil stains in traction sheave grooves and wire ropes, severe wear of the brake wheel and brake tile, excessive clearance between brake wheel and shackle, stuck brake arm, broken speed limiter wire rope, incorrect installation or improper adjustment of safety clamp are the priorities of control. Therefore, managers need to pay high attention and strengthen on-site supervision. It is also shown that the FFTA-FMEA method combines probabilistic imprecision and engineering imprecision, simplifying complex problems and improving flexibility, and demonstrating its potential for widespread application in the field of reliability engineering. Similar to lift-jacking accidents, other common lift incidents require their risks to be identified, analyzed, and assessed, and measures taken accordingly.  
The greatest limitation of this study is the relatively small number of experts consulted. In future studies, selecting more experts with greater seniority and skills may further improve the accuracy of the model. In addition, although the AP method addresses the problems of the traditional RPN method to some extent, they are still essentially the same. More variants of the FMEA method can be chosen to continually improve the accuracy of the risk assessment.  
Conceptualization, N.X. and K.D.; Methodology, N.X. and K.D.; Software, B.Z.; Validation, W.Z. and B.Z.; Investigation, K.D. and W.Z.; Resources, F.L.; Writing--original draft, K.D.; Writing--review & editing, N.X.; Supervision, F.L. and B.Z.; Project administration, N.X. and F.L.; Funding acquisition, F.L. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Fundamental Research Funds for the Central Universities, grant number 2019 ZDPY08.  
Data Availability Statement: The data that support the findings of this study are available on request from the corresponding author.  
The authors declare no conflict of interest.