Research On Safety Assessment Methods Of Quayside Container Crane

Quayside container crane is one of the key equipment for the port dock.Due to the complex structure,hight-speed work requirement,various working condition,as well as extended service,the safety of quayside container crane is challenged by potential risk.Improving the accuracy of safety evaluation is a significant focus in the process of current safety management of quayside container crane and one of the urgent problems to resolve.Therefore,researches on quayside container crane safety evaluation possess both theoretical and practical significance.Aiming at the critical problems in crane safety assessment,the system thorough researches are conducted for the theoretical system of quayside container crane safety evaluation based on variable fuzzy sets and combination weighting model of game theory from the perspective of system engineering.Some theoretical and practicable results are obtained.And the main research works are described as follows:(1)Aiming at the requirement of crane safety assessment,we deeply investigate safety assessment theory and compared characteristics of common evaluation methods.We propose a method for crane safety assessments using cumulative prospect theory(CPT).And it is applied to calculate the overall prospect values.The safety grade is then identified according to the ranking of the overall prospect values.The results obtained by CPT are completely consistent with those given by grade feature value equation and grade discriminant criterion of variable fuzzy sets.The proposed CPT safety assessment can overcome such drawbacks as the principle of maximum degree of membership,confidence criterion.The obtained results demonstrate that the CPT method described in this dissertation can precisely and reasonably reflect the safety status of a crane.(2)Considering the evaluation method of traditional variable fuzzy sets(VFS),we propose an improved model of variable fuzzy sets(IVFS)and apply it to crane safety assessment.Traditional VFS evaluation processes are rather complex and tedious.In this paper,we provide an IVFS evaluation method with normal membership function for solving crane safety problem,in which the evaluation criteria are described in terms of intervals.In some situation,the wrong result can be obtained by grade feature value equation and grade discriminant criterion of variable fuzzy sets.Aiming at this problem,we combine grade feature value equation,grade discriminant criterion and confidence criterion to determine safety grade.The calculation of an example demonstrates that the assessment results obtained by the proposed model are more reasonable.(3)To overcome the drawback of traditional combination weighting of game theory,we propose an improved combination weighting model of game theory(ICWGT).Combination weight can fully use objective information provided by attribute values as well as utilize decision-makers' experience and knowledge.The index weights determined by combination weighting method are more reasonable.The improved combination weighting model can avoid negative values in the weight coefficient.Compared with the interval estimation method,particle swarm optimization method and the minimizing deviation combination weighting,the results demonstrate the effectiveness of the proposed method.(4)Sufficient and systematic researches on quayside container crane safety problems are not enough.The related researches focus on the damage modes of metal structure,and rarely involves working environment,safety management and other factors to quayside container crane safety.Through investigating quayside container crane accident statistics,we consider the characteristics of the quayside container cranes,and distinguish the main hazardous and harmful factors of the system based on system engineering.Quayside container crane system is divided five subsystems which are metal structure system,main body and parts system,electrical equipment system,security protection system,the use and management system.The evaluation contents of five subsystems are described in detail,which provides the basis for establishing scientific and reasonable safety evaluation index system of quayside container crane.Finally,the problem of standard division and measurement of safety evaluation index of quayside container crane is discussed.(5)An IVFS multi-level safety evaluation model is proposed and applied to evaluate quantitative index safety of quayside container crane.The method integrates the subjective and objective weight of the evaluation index with ICWGT.And the safety level of the evaluation object is determined according to the improved variable fuzzy evaluation method.The model is applied to the safety evaluation of the quayside metal structure system.The variable fuzzy level calculation method is used to determine the safety level directly based on the relationship between the index evaluation index and the index evaluation standard.The proposed method solves the problem that the evaluation levels of the metal grade index are not consistent with the standard grade of the system evaluation standard criteria.By comparing with the traditional evaluation methods,it is verified that the method proposed is suitable for metal structure safety evaluation of quayside container crane.The results demonstrate the rationality and availability of the proposed model.(6)An evaluation model is built on the basis of IVFS and used to evaluate qualitative index safety of quayside container crane.Improved analytical hierarchy process and information entropy method are used respectively to determine subjective and objective weights.Then ICWGT is applied to fuse subjective and objective weighting information.In order to solve the inconsistency of expert opinions,ICWGT is used to aggregate weight coefficient of the experts based on group decision making idea.Then the index scores are determined.Membership degree matrix is calculated through IVFS.Then the proposed approach is applied to evaluate the protective device safety of quayside container crane.Finally,the analysis and comparison of the evaluation results are also conducted to show that the proposed model is feasible for assessing qualitative indicator safety of quayside container crane.