Research On Risk Assessment Of Prefabricated Component Appearance Quality Defects Based On Fault Tree-bayesian Network

As the smallest component and key foundation of prefabricated buildings,the quality of prefabricated components directly affects the performance of prefabricated projects.The quality defects of prefabricated components can be divided into structural quality defects,dimensional quality defects and appearance quality defects according to the function.According to the statistics of the research report on the development of the national prefabricated component factory over the years,the appearance quality defect is the most frequent type of quality defect of prefabricated components.Appearance quality defects will not only affect its structural performance,but also affect the subsequent installation and construction of prefabricated components.Moreover,the annual production capacity of prefabricated components is huge,and the scale benefit is bound to significantly increase the repair cost of enterprises.However,at present,there are few studies on the risk prevention and control of appearance quality defects of prefabricated components at home and abroad,and most of them are based on qualitative analysis.The quantitative research on the formation mechanism and key causes of appearance quality defects is insufficient.Therefore,in order to effectively reduce the risk of prefabricated component appearance quality defects,reduce the repair cost of enterprises,and improve the quality risk management level of prefabricated component production enterprises.Based on the establishment of the hierarchical structure of the formation mechanism of the appearance quality defects of prefabricated components,this paper constructs a quantitative evaluation model of the risk of the appearance quality defects of prefabricated components to solve the above problems.The main contents of this paper are :Firstly,the formation mechanism of appearance quality defect risk of prefabricated components is analyzed.Taking the appearance quality defect components as the research object,the 11 process risks caused by the appearance quality defects of prefabricated components are identified from the perspective of the production process of prefabricated components.Based on the results of literature retrieval and field investigation,a list of risk factors affecting the appearance quality defects of prefabricated components was identified.The formation mechanism of appearance quality defect risk is analyzed from top to bottom by using fault tree analysis method,and the formation path hierarchy of appearance quality defect risk of prefabricated components is constructed.Then,a risk quantitative evaluation model of prefabricated component appearance quality defects based on Bayesian network is constructed.According to the mapping rules of fault tree to Bayesian network,the fault tree model is transformed into Bayesian network topology,and the risk transfer path model of appearance quality defects is constructed.The data information of the appearance quality defect sample component is collected by means of questionnaire survey,and the prior probability of the Bayesian network root node is determined.The conditional probability table of non-root nodes in Bayesian network is calculated by using the sample space reduction method,and the parameter learning of Bayesian network is completed,so as to construct the Bayesian network quantitative evaluation model of prefabricated component appearance quality defect risk.According to the output results of the model,the diagnostic reasoning,sensitivity and maximum cause chain analysis of the appearance quality defect risk of prefabricated components are carried out,and the corresponding control countermeasures are put forward.Finally,the quantitative evaluation model of appearance quality defect risk of prefabricated components is verified by practical cases.The relevant data of a prefabricated component production enterprise are input into the Bayesian model for evaluation and application.The control points of the enterprise ’s appearance quality defect risk in the production process are identified,and the scientificity and applicability of the risk assessment model of prefabricated component appearance quality defect are verified.The results show that :(1)In the production process of prefabricated components,process template installation,steel bar binding,concrete vibrating and finished product hoisting are the high risk processes of appearance quality defects of prefabricated components;(2)Among the risk factors that cause appearance quality defects,the key causes of appearance quality defects are not strict template splicing,not strong reinforcement binding,insufficient concrete vibration,excessive component span,and unreasonable selection of lifting point position.Combined with the results of case analysis,the control of the above key causes can significantly reduce the probability of appearance quality defects.This study provides a strong basis for the systematic prevention and control of the appearance quality defect risk of prefabricated components,and provides guiding suggestions for prefabricated component manufacturers to formulate risk prevention countermeasures.