Study On Construction Safety Risk Assessment Method Of Cable-stayed Bridge Based On Cloud Model

Cable-stayed bridges are loved for their generous appearance,beautiful shape and unique structural features.The construction of cable-stayed bridges in China has developed rapidly in recent years.With the innovation of technology and structure,many uncertain factors have been added in the construction of cable-stayed bridge,which puts forward higher requirements for the construction safety of cable-stayed bridge.Once a risk accident occurs,it will cause great losses.Taking the long-span single-tower cable-stayed bridge with hybrid girder as the research object,this paper mainly studies the model,method and application of safety risk assessment during the construction of cable-stayed bridge.The main research results are as follows:(1)Construction of construction safety risk index system and weight calculation model of cable-stayed bridge.On the basis of identifying the construction risk of cablestayed bridge from four aspects: literature research method,accident cause theory,construction accident statistics and construction method analysis,the weight of risk factor is calculated based on the combination of cloud model theory,network analysis method and entropy method.And the construction risk weight calculation model of cable-stayed bridge is constructed.The expectation,entropy and super-entropy of the cloud model are integrated into the process of weight calculation,and the problems of subjectivity and averaging of weight distribution are solved.(2)Probability estimation of construction safety risk of cable-stayed bridge.Taking the bridge tower construction,tower beam synchronous construction and steel box girder construction as the research object,the reliability of the structure is analyzed by using probabilistic finite element method(FEM)with ANSYS.Considering the uncertainty of quantitative factors such as material,wind load and temporary load,the failure probability of the structure in each construction stage is obtained,and the parameter sensitivity is analyzed.The results show that the uncertain factors have the greatest influence on the structure in the tower-beam synchronous construction stage,while the structural reliability of the steel box girder is the greatest in the construction stage.The uncertainty of the wind load of the input variable has the most significant influence on the structural reliability.The magnitude of wind load and the angle of attack have a certain influence on the structural reliability,but the influence of wind load on the structure is greater in the tower-beam synchronous construction stage.(3)Construction of construction safety risk assessment model of cable-stayed bridge.Based on the two-dimensional cloud model,each risk index is evaluated by twodimensional variables based on the possibility and consequence of risk,and a risk assessment model is constructed.Combined with the index weight to calculate the digital characteristics of the two-dimensional comprehensive cloud model,a similarity calculation method compared with the standard cloud is proposed.The construction safety risk grade of Yuekou Hanjiang Bridge is shown intuitively and comprehensively,and the corresponding measures are put forward according to the main risk factors obtained from the analysis.Finally,the rationality of the model is verified,and the rapid risk assessment is realized by compiling the risk assessment system.