| With increasing number of bridges crossing inland waterways,strait and gulfs,and rapid development of vessel transportation,the collision accidents between vessels and bridges occurred frequently,which caused bridges damage or collapse. Risk accidents of ship collision with bridges may involve many uncertain factors.How to assess them and reduce their frequeciesto an acceptable level are the main topic of the dissertation. This dissertation focuses on the ship collision risk analysis of large span prestressed concrete girder bridges,which includes the following aspects:1. The paper reviewed and summarized the researches and progress on ship-against-bridges problems both at home and abroad,including the researches on the mechanical ship-against-bridges models,the risk assessment of the ship against bridges(including the ship against-bridges probability,consequence and the risk prineiples),researches on the ship-against-bridges accidents,the design methods of preventing ship collisions on bridges and researches on the ship collisions on bridges.2. The theoretical skeleton in this part, the risk conception and its analysis principle are discussed.The definition of risk and the selection principle of risk analysis methods are put forward, the definition of the ship collision risk of large span prestressed concrete girder bridges is given and the theoretical skeleton of the ship collision risk analysis for bridges is built.3. Based on the MATLAB language and basic data of the present sample,4chief influential factors as the input coefficient,such as the bridge span,the water flow rate,the incline angle between water flow direetion and the direction normal to bridge axis,and the curve in the course near the bridge area,with the ship-against-bridge probability as the output coefficient,the intelligent judging system of the ship-against-bridges probability reflecting the influence of the above input parameters is obtained after training.4. The paper recomded the ship collision probabilistic reliability analysis based on ANSYS finite element. The traditional method of solving the structural reliability has many shortage, so this paper useing the finite element software ANSYS and the Monte-Carlo numerical simulation (F-M)to analyze the structural reliability.5. The risk criteria of vessel-bridge impact are studied.Based on comparing and researching relevant norms about vessel-bridge impact,risk levels of various industry and natural disasters,and existing accidents in our country,and recommended the collapse of the ship collision risk acceptance criteria and assessment criteria. The frequency of the bridge collapse is high risk when it is greater than 10-3 , 10-5 10-3 is medium risk, 10-7 10-5 is low risk ,less than 10-7 is the negligible risk .And recommended a preliminary risk treatment measures.6. Projects-ship collision risk analysis of Beishan-Bridge. Using the ship collision risk assessment theory of prestressed concrete girder span bridge analyzed the ship collision risk analysis of the Beishan-Bridge.Finally, the full paper of the work done by the study are summarized, and future research work is prospected.
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