Research On Safety Risk Assessment And Application Of The Existing Bridge In The Arid And Cold Region Of North-west China

With the development of transportation industry in our country, highway bridges has played a more and more important role. And how to ensure the safety of the using bridge is an urgent problem need to be solved for bridge managers, the most important task of keeping bridge using safety is the bridge safety risk assessment. Thus, it is necessary to study on the safety risk of existing bridge. So, paper gives the safety risk assessment system of using bridge, and studies on the disease of statistical analysis, safety risk probability and loss, safety risk evaluation combined with the existing bridge in the arid and cold region of North-West China.In the stage of establishing the safety risk assessment system.Paper gives the concept of bridge safety risk assessment, ensures the basic idea of safety risk assessment of bridge is the process of risk assessment based on bridge safety, confirms that the content of bridge safety assessment is consist of safety risk theory and safety risk methods, reveals the relationship among the contents of the existing bridge safety risk assessment. The paper also build the evaluation index system of the existing reinforced concrete beam bridge combining with the relevant specifications and standards. All these jobs make the necessary preparations for the follow-up study.In the stage of safety risk identification and estimation.After sort out the disease data of 141 bridges in Yongchang to Shandan section of Lian Huo highway, identified the main diseases of existing reinforced concrete beam bridge there. Using the maximum likelihood estimation method and the K-S method established and tested safety risk probability models of the main diseases. For those diseases which data quantity are so less that not enough to establish the safety risk probability models, use the membership function method to solve the problem. And try to introduce the analysis of human- machine reliability method and Rook method into the field of existing bridges safety risk assessment, which two methods are used to determine the probability of buried safety risk factors in the design and construction stage of the bridge.Divide the loss of existing bridge safety risk into economic lost and non-economic loss. Using the cost of the asset valuation method to build the lost model of bridge structure, the lost model of bridge affiliated structure, the lost model of moving property on bridge. For non-economic loss, rely on the method of willingness to pay to establish the quantitative model of value of life in different sectors. At the same time given the time lost quantification model of passengers and goods in transit, also given the quantitative model of the environmental loss and the social loss in the ecological protection area.In the stage of safety risk evaluation.Built the fault tree with weight based on existing reinforced concrete beam bridge in the arid and cold region of North-West China, derived the calculation formula of the top event probability. Using extension method built a safety risk decision model, which method can solve the problem that indexes in different units making decision at the same time. In the process of making decision, according to the actual engineering situation and the preference of decision makers give decision weights, to help the decision makers to make more effective decision scheme.Paper introduced the safety risk assessment method into the field of bridge safety evaluation, researched on the safety risk identification, safety risk estimation, safety risk evaluation and safety risk decision-making of existing bridge in the arid and cold region of North-West China by using the method of risk assessment and safety assessment. All these researches are aiming at constructing a set of safety risk practical assessment system of the existing bridges. On the one hand, it can enrich the safety risk evaluation theory and evaluation method of bridge in service, on the other hand, use safety risk assessment methods provide decision-making basis for bridge managers, guarantee the safety of the using bridge.