Risk Assessment Analysis Of Long-Span Cable-Stayed Bridge In Wind Disaster And Seismic Disaster

Long span cable-stayed bridge is the fastest development and the most competitive bridge type in modern bridge engineering due to its long span ability and novel structure, It is a complex structural system and there are many factors affecting safety of the structure; Earthquake and typhoon are major natural disasters to human, the probability of failure of the bridge structure in earthquake or wind will directly affect relief work after disasters. Therefore, risk assessment analysis of long span cable-stayed bridge in wind disaster and seismic disaster is quite necessary.The work of bridge risk assessment was started late, there is not complete theoretical system and assessment method for risk assessment by now; In this master degree thesis, according to the characteristics of cable-stayed bridge structure, analysising the probability of wind disaster and earthquake disaster and combining with the structural reliability theory, the theory system of risk assessment of long span cable-stayed beidge in wind disaster and seismic disaster is studyed, the main works include the following aspects:1) After studying risk defintion in relevant industries, wind disaster and seismic disaster risk definition of cable-stayed bridge is proposed, the risk assessment theory framework of cable-stayed bridge structure in wind disaster and seismic disaster is established, which is combined with characteristics of wind resistance and seismic resistance of this kind of bridge.2) Analytic hierarchy process is applied to identificate risk factors in seismic disaster and wind disaster to risk identification, the complex risk factor of cable-stayed bridge will be disintegrated for each element, risk factors in wind disaster and earthquake disaster of cable-stayed bridge structure will be organized and hierarchical, a system risk analytic hierarchy model of cable-stayed bridge structure is established.3) Based on the risk probability model of cable-stayed bridge, the hierarchy analysis process-finite element model-Monte Carlo assessment method is established on the basis of risk identification and reliability theory to assess the risk of cable-stayed bridge during the design working life of cable-stayed bridge when typhoon and seismic disaster occurr, a wind disaster and seismic disaster risk assessment method of cable-stayed bridge is established.4) Studying on the cable-stayed bridge seismic disasters and wind disaster risk assessment system which is based on ALARP standards of decision criterion, the risk decision theory is introduced into the risk assessment system of cable-stayed bridge, through to generalizing and summarizing the other industry risks assessment norm and combine with the ALARP guidelines, a risk qualitative and quantitative assessment norm of cable-stayed bridge is proposed, which provides academic basis for decision makers to solve the decision-making.5) Research results are applied to risk assessment of a long span cable-stayed bridge in wind disaster and seismic disaster, coping strategy based on risk appraisal is proposed, which tests the theory system.