Transverse Cracks In The Impact Analysis, The Stiffness And Bearing Capacity Of Prestressed Concrete Box Girder Structure

With the development of the prestressed concrete construction technology, more and more prestressed concrete box girder bridges have arisen in our nation. However, after construction, the appearance of the cracks on some of these bridges takes some unfavourable influence on the structures. In common sense, we should take some methods to strengthen and repair these bridges as soon as possible, but because of the civil pecuniary condition, we can't repair all the broken bridges in one time. Therefore a scientific estimation must be made about the load-carrying capacity of these prestressed concrete box girder bridges with cracks, so that we can decide which bridge should be repaired firstly. But the research on the prestressed concrete box girder bridges with cracks does not carry out very well, so there is no accurate and reliable method to analyzing these structures in recent China.This paper, which is one part of the western project about communication science and technology which mainly discusses the cause and the disposal technology of the cracks occurring in the continuous prestressed concrete box girder bridge, mainly studies the influence of the cross direction cracks appearing in the middle span on the load-carrying capacity and the stiffness. Therefore it can provide some reference to the research of the prestressed concrete box beam bridges with cracks. The research in this paper adopts the finite element numerical analysis method.Based on the statistic parameter of cracks which is established according to the external appearance inquiry of the broken bridge, the real cracks is converted into the statistic average cracks. And then, under the help of the finite element model, these statistic average the cross direction cracks which occur in the middle span of the box beam is simulated. After comparing the analysis result of the finite element model simulating the undamaged bridge and the model simulating the cracked bridge, the discount rate of the load-carrying capacity and the stiffness is gained.Moreover, during the course of the research, a lot of different finite element model is adopted to simulate the cracked bridge. After comparison of these different models, the author gets some conclusion and suggestion on the simulation of thecross direction cracks, and, at the same time, the regular rule of the influence by the different pattern of the cracks is also gained.