Reliability Evaluation Of Certain Continuous Beam Bridge Pre-and Post Reinforcement Base On Fuzzy Comprehensive Theoretical

As traffic increased, the overload more serious, and other natural factors and human factors influenced, there are being different levels of damage in existing bridge, which will inevitably lead to loss of the carrying capacity of existing bridges, and performance degradation, and durability reducing. With the development of urban and rural roads, bridges becomes more and more important in the national economy and social life, and the reliability of existing bridges takes more and more attention. At present, the research on the reliability of existing concrete bridge is not abundant, which is the starting point of this paper.Fuzzy comprehensive evaluation method is an effective way to evaluate the reliability of existing bridges, the main process is that:first to create bridge's index set. followed determine the weight of evaluation index and membership grade function of evaluation index on evaluation grade, thirdly make a fuzzy evaluation according to the site test result and calculation result of existing bridge's carrying capacity.finally make a fuzzy calculation according to the fuzzy calculation method, and judge bridge's reliability grade according to the fuzzy grade judgement method.In this paper, for making the right engineering decision, use fuzzy comprehensive theory to evaluate the reliability of certain continuous girder bridge. The main works are as follows:(1) upholding the previous evaluation index set namely{strength, deformation, fracture}, perfected the fuzzy comprehensive evaluation system:introduced the concept of variable weights, and depth studied of membership function of evaluation index on evaluation grade.(2) proposed failure-mode-searching method of existing continuous girder bridge and carrying capacity calculation theory, Failure mode-searching and capacity calculations to certain continuous girder bridge before and after reinforcement were carry out(3) Reliability evaluation to the Etouwan Overpass (5 span continuous girder bridge) before and after reinforcement were carry out with fuzzy comprehensive evaluation method.The results of reliability evaluation of the Etouwan Overpass's are:Before the reinforcement, bridge grade level is 3, bridge need strengthening. After the reinforcement, the bridge grade level is 1, and carrying capacity meet the reliability requirements. the evaluation results of Fuzzy comprehensive theory is similar to conclusion of bridge expert's discussions in Wuhan city, that prove the evaluation method is feasible.