Research On Disease Treatment Methods And Reinforcement Effects Of In-Service Prestressed Concrete Hollow Slab Beam Bridges

With the rapid development of economy in China since 1980s, the bridge construction, as a part of the highway traffic infrastructure construction, has obtained great achievements. Because of its economical efficiency, hollow slab beam, as one of the important forms of bridge structure, has been widely used in highway bridges. In most of highways which were constrcuted in early period, hollow slab beam is as high as 80%～90%. However, with the rapid increase of the traffic volume, problems have also been exposed gradually and the prestressed hollow slab beam has also suffered from many diseases.At first, this paper introduces the present situation and typical diseases of the in-service bridges at home and abroad, especially for the prestressed hollow slab beam. While analyzing the causes, we put forward disease treatment methods and focus on research status of three reinforcement methods including bonding steel plate, external prestressing and internal prestressing.Secondly, we sum up current methods of evaluating reinforcement effects. Based on the analysis and discussion of the problems in the evaluation indexes, this paper proposes the methods of testing the evaluation indexes including degree of prestressing, stress amplitude of steel wire and crack width.At last, applying the research results into an engineering project of a 25m post-tensioned prestressed concrete hollow slab beam, this paper evaluates the effects of three kinds of reinforcement schemes objectively, and draws some reasonable conclusions.Through the research of this paper, we can see that bridge reinforcement is a systematic and complicated project. By the procedures of "visual inspection-bridge diseases test reinforcement design-reinforcement construction and monitoring-reinforcement effects evaluating", we can grasp the cause of diseases accurately, have better bases for reinforcement schemes, control the risks of reinforcement and evaluate the reinforcement effects effectively, making the whole reinforcement project under safety and controllable.