Concrete Box Girder Cross-section Analysis Of Coordination

Box-section structure with good performance is using in a wide variety of applications in the modern bridge building. Reinforced concrete box girder to the current method of application of the general theory is the beam theory. That is, the box is hold up the role of tension, pressure and bending resistance ,so the box is to simplify the calculation by the general beam theory. The coordination function is negligible on the box in the lower partial load plate and the top and bottom of the transition region.The finite element method of numerical analysis is applied to in this paper, at the same time, using ANSYS general-purpose program to simulate the analysis of concrete box. Through the establishment of 16 meters long, 12 meters wide, 4.5 meters high form of simply supported box girder model, and both ends without the original model, concrete box-section part of a different stress situation is studied in the partial load. The original model as a basis is to study the concrete box on the roof with the web transfer region in the case of different form of the size of the thickness of the web. As well as ,the changes of the beam highness has influence on the internal organs of the impact. The thickness of the sealed box girder has influence on the internal organs of the impact of stress.The analysis showed that: (1) In the partial load, the strains curves of the concrete box includesεx,εy andτxy showed that major inflection point and a turning point. The concrete box-section top and bottom with the web transfer region is evident in the region the deformation of the non-conforming. (2) The concrete box girder cross-section is changed in the web thickness, with the decrease of its thickness will increase the co-ordination in the transition region of the top board with the web and in the transition region of the bottom board with the web, and extend the scope of the impact of the strain curves. As well as, with reducing the thickness of the web, the strain ofεz will not be able to maintain its linear curve which can not remain the assumption of the flat box section for cross-section. (3) Box-section changes in the highness of the beam. With the reducing the highness, the co-ordination of the transition region will increase in the top board with the web and in the bottom board with the web. But reducing the highness of the beam web has increased the vertical stiffness of the web, the strain curve ofεz will gradually maintain the linear curve. (4) Both sides of the sealed box has little impact on coordination that is client-side cross-section of the beams transfer of the region in the top and bottom board with the web, but it would make the whole box in the entire cross-section between the strain curve to maintain similarity. At the same time, it will improve the box-section to maintain the overall capacity.The coordination of the structure will be improved through adding to the haunch. Adding to the haunch in the junction of the top board with the web, the rate of the strain curves ofεx,εy andτxy will reduce with increasing the gradual deformation of the coordination. When the haunch area of the top board with the web add to 0.45mX0.45m, further increasing the area of the region the haunch deformation effects can be neglected. The haunch area of the bottom board with the web add to 0.30mX0.30m, further increasing the area of the region the haunch deformation effects can be neglected. The reasonable regional size of the haunch is the effective reduction in the level of stress concentration, and do not increase too much self-respect, so that box-section by a more reasonable power has played a good structural properties.At present, the study of the coordination of the concrete box girder cross-section is rarely seen. As well as, the stress of box cross-section is complicated with the changes in forces and influenced by many factors, but the box has a wide range of applications, which should continue to strengthen research in this area. The further box cross-section research is now added the study of the inadequacies of theory, and better to guide a more rational form of concrete box girder design, construction and applications.