Researches On Closure Scheme Of The Long-span And Long Connected Concrete Continuous Girder Bridge

The prestressed concrete continuous box grider bridge has been widely applied, with its good structural stiffness, small structural deformation, smooth and comfortable journey, etc.With the deepening of the design theroy and the development of the construction methods, especially with the application of the high strengh materials, prestressed concrete continuous grider bridge is advancing toward long-span and long connected. However, at the construction and using stage of the long-span and long connected concrete continuous girder, closure segment appear cracks and the accidents of bursting crack occur frequently, so the enormous security hidden danger were created, and have brought to the widespread attention.This paper took the Feiyun River bridge as the engineering background, and then the finite element stimulation calculation and closure optimization were carried out. The main work is as follows:First, the tension batch of prestressed tendons was study at the closure segment and nearby areas from the backplane longitudinal prestressed and the roof crosswise prestresed. In the backplane logitudinal prestressed aspect, analyed the influence of different length and short tendon order on the internal force and deformation at the construction stage and the bridge completed stage. In the roof crosswise prestressed aspect, introduced the transverse internal force analysis method of the box girders, carried on optimized reserch on tension batch through examples. Analyed the roof crosswise prestressed effect of different length of the final tension area, then obtained the relationship between the roof crosswise prestressed and the length of the final tension area.Second, in order to study the influence of the cantilever age differences between both sides of the closure segments on the main beam’s situation, this paper put forward an optimization program which has no cantilever age difference on both sides of the construction plan and the design plan, coMPared the three plans’s internal force and deformation at the construction stage and the bridge completed stage, then obtained the relationship between the main beam’s internal force, deformation and the cantilever age differences between both sides of the closure segments.Third, the structural syestem conversion occurs at the same time the internal force redistribution when the bridge was closured, so the closure sequence and the removal time of temporary consolidation have a great iMPact on the main beam’s internal force and deformation. In order to study the influence of the closure sequence and the removal time of temporary consolidation on the main beam’s situation, this paper stimulated a variety of closure sequences, for example, from side span to mid-span, from mid-span to side span and so on, stimulated plans with different removal time of temporary consolidation. Finally, coMPared the results of the above plans obtained the optimal closure sequence and the best time to remove temporary consolidation.