A Bim Based Risk Analysis Method For Ancient Buildings Based On The Fault Tree Analysis Coupled Cloud Models With Modified Entropy Algorithm

The present paper studies a typical old wooden structure building with the characteristic of significant deterioration,multiple diseases,and complex damage distribution to improve the ability of the diagnosis and prediction of their potential failure risks during the period of the construction operation and maintenance,as well as to enhance the level of building information utilization.Based upon the improved method of entropy and hyper-entropy calculation,the paper proposes a risk assessment method named IEFTC which consists of fault tree analysis(FTA)and improved cloud model.Throughout the evaluation process,BIM is used for data integration and risk visualization.To implement the proposed algorithm,firstly,the fault tree analysis is constructed to form a risk map of failure mode by describing the correlation between events.Secondly,the characteristic values of the bottom events are generated and aggregated by the cloud model algorithm with the improved method of entropy calculation.Specially,Taking the variance of different evaluating results into account,the method not only retains the experts’ evaluations on potential risks of events,but also quantifies the dispersion degree of different evaluations.When the bottom events get their basic cloud model,the cloud models of upper events will be aggregated by virtue of the aggregation algorithms in the cloud model theory,and the aggregation algorithms vary with different logic gates in FTA.Consequently,the fuzzy information has been transferred and a more reasonable analysis result has been obtained based on the retained risk information.In the information management of ancient buildings,the paper uses BIM technology to record assessment data and realize the automatic judgment of building risk level relying on computer program.And we realize the visualized presentations of the risk levels of different components by using color legend in building information models.The method fully uses the advantages of the cloud model in processing uncertain information and improves the ability of FTA to process and transmit uncertain information.Results show that the proposed method can effectively improve the efficiency and accuracy of the risk assessment of complex structures of multiple diseases.The main contents of this study are as follows:(1)Measure the dispersion of the evaluation data by standard deviation and construct an additional adjustment coefficient based the quantified data.In this way,the calculation of entropy has been improved and the evaluation information can be fully extracted and utilized.(2)Describe reasonably the logical relationship and causal relationship between events at different levels through the fault tree.Then,a universal applicable assessment framework can be built.On this basis,introducing the cloud model to improve the processing ability of FTA for uncertain information.(3)Establish a BIM information integration and visualization platform and operate the IEFTC algorithm based it to realize information circulation and visual risk management.Breaking the limitation of emphasizing models but neglecting data in the research of ancient building informatization.