Risk Analysis Of Long-span Cable-stayed Bridge With Single Cable Plane And Steel Truss Girder In Construction

The steel truss girder cable-stayed bridge with single cable plane is belongs to themulti hyper-static structure. In this kind of bridge, the connection structure of cable andtower as well as girder is complex, the calculation for the design is difficult, the aloftwork is heavy, the cable force are large and concentrated, the number of single cablesteel strand is huge, the torsion strength is poor. Moreover, it is hard to control theuniformity of the stay cable and hard to adjust the cable force. In addition, there is littletheoretical knowledge about this type of bridges in domestic as well as in foreign. Allabove make the construction is hard to control and the risks during the constructionperiod is large. In order to improve project quality and reduce the occurence of projectaccident, the risk analysis and risk evaluation for steel truss girder cable-stayed bridgewith single cable plane is needed during construction.According to the problem happened in the construction control of cable-stayedbridge, combined with the characteristics of bridge construction process, the AHP-greyrelational theory-the finite element analysis-Monte Carlo theory-RBF neural networkcomprehensive evaluation method is adopted to study the construction risk of long-spancable-stayed bridge with single cable plane and steel truss girder.Because that the analytic hierarchy method have clear hierarchy and can transferthe qualitative evaluation to quantified identification, so this research adopts analytichierarchy method to identify the main risk sources during the bridge construction anddetermine the relative importance weights of the main riskas well as build the rankinglist for the bridge risk factors.Since the selection of Qiansimen bridge structure has the characteristics of graysystem, the grey correlation analysis method combined AHP method is adopted to provethe superiority of single cable plane structure in Qiansimen bridge.Combined with the finite element analysis, Monte Carlo theory and RBF neuralnetwork method,the risk comprehensive evaluation method is proposed. Throughestablishing the finite element model, the quantitative analysis for the verticaldisplacement of cantilever ends of Qiansimen Bridge in cantilever state is conducted. Inorder to make the material parameters correspond to the statistical requirements, theradial basis function neural network is used to analyze the displacement of cantileverend quantitatively. Finally the Monte Carlo theory is adopted to determine the probability of risk and to increase th credibility.This paper enumerates the preventive measures for the high weight risk of theQiansimen bridge in the appendix.In this paper, based on the analytic hierarchy method-grey system theory-finiteelement model-Monte Carlo theory-RBF neural network, a quantitative risk analysismodel is built for the large span cable-stayed bridge with single plane construction.Using this model, the objectivity of risk analysis is improved and the high reliability isachieved. This is a new exploration in the quantitative risk analysis for bridge, and wehope that it can provide certain reference value for the risk analysis theory of the steeltruss girder cable-stayed bridge with single plane construction.