Construciton Secuirty Risks Analysis And Contorl Of Superstructure Of Long-span Cable-staved Bridge Based On Bavesian Belief Network

The superstructure of long-span cable-stayed bridge is a kind of high-orderstatically indeterminate spatial structure, the construction technology is complex, andthe uncertain risk factors are diverse, so the security risk control and management arethe most important parts for construction management during the construction oflong-span cable-stayed bridge. In the engineering practice right now, the long-spancable-stayed bridge superstructure security risk management and control mainlyconcentrated on construction control and qualitative security control based on stressand strain control and the bridge geometry. In theoretical research, a comprehensivesystem of long-span cable-stayed bridge superstructure security risk management is thefirst stage of exploration, the guidance of the theory in practice has not yet formed afavorable support. Research and the establishment of a scientific long-spancable-stayed bridge superstructure construction safety risk analysis and managementtheory, not only has great significance for improving the project risk managementtheory but also has important practical significance to guide the long-span cable-stayedbridge construction safety risk control.As the need of improvement for the theory of superstructure construction securityrisk management of long-span cable-stayed bridge and the construction practical callfor advanced theory of construction security risk management, this master degreethesis have stadyed the superstructure construction security risk management oflong-span cable-stayed bridge based on the theory of risk analysis and bayesian beliefnetwork. Firstiy, this paper studies the long-span cable-stayed bridge superstructureconstruction characteristics and the security risk problem in exist, according to thenanlysis, summarized the domestic and international cable-stayed bridge superstructureconstruction safety accidents; Secondly, established the risk assessment model of thesuperstructure of long-span cable-stayed bridge on the basis of the analysis of thecharacteristics of the structural safety risk, combined with risk analysis theory andbased on Bayesian network theory. Thirdly, this paper studied the potential risk factorsduring the superstructure construction,and then summarized them into17risk events,established the risk assessment model of bayesian belief network. This paper studiedthe probability estimation method based on Bayesian belisf network for long-spancable-stayed bridge superstructure construction, and amended the probability ofoccurrence data by the principles of Bayesian statistical and inference, calculate theprobability of occurrence of risk events; Finally, the use of risk assessment matrix riskevent carried out the risk classification，then calculate the contribution of risk factors tothe risk events itself, proposed risk control measures concentrate on risk events,at thesame, risk factors are analyzed to get technical risks, natural risks etc. five sorts and theexpect risk loss value of themselves. All of these will be helpful for the superstructureconstruction risk management. This paper is completed combined with the basic scientific research project of theMinistry of Transportation "the whole process of project construction risk analysis andcontrol"(ID:2005319814030) and the horizontal research project " The SecondChongqing Fengdu Yangtze River Bridge construction safety risk analysis andcontrol".