Application Of Shear-flexible Grillage Method In Irregular Girder Bridge Analysis

Now the application of special-shaped bridge is more and more widely, At the joint of main structure and the ramp, irregular box girder that is tapered and curvature-changing is always adopted. However, the theoretical analysis and the Analysis Method Of irregular girder bridge and curved bridge developt Very slow,is difficult to adapt to the needs of construction projects. So the study of special-shaped box has become necessary.On background of the design proposal of some irregular box girder bridge, used a large-scale FEM software Midas/Civil to model and analysis. And the main content of irregular girder bridge is as follows:1 .The basic theory of grillage analogy method to module box girder is studied systemic, the principles that how to divide the grillage, how to calculate the constants for longitude beams and transverse beams, and how to deal with the results gotten by grillage analogy in box girder bridge are analyzed detailedly, and the reasonable principles are proposed.2.In order to investigate the feasibility and accuracy of grillage analogy method, the grillage model as well as the shell element FE-model is established, and the corresponding stress and displacement results of girder rib and transverse beam from the two models are compared, so is the constraint reaction, then reaches the conclusion that the displacement results are in good agreement, and the normal stress results from grillage analogy method are acceptable from an engineering design standpoint.3.In the designs of the irregular box girder engineering, It is usually make use of load transverse distribution factor to considered the impact of eccentric load, in this papers it used stress and displacement to calculate the load transverse distribution factor of irregular girder bridges of different spans4.At present, Some irregular overpasses have supporting diseases, It can be seen that the layout of support for irregular girder bridge has a great influence on the force of the structure,the paper compared the rib beam internal forces, transverse beam internal forces, support reaction of three different schemes,then give some recommendations on the layout of support.5.The effects that the amount cross diaphragm rigidity have on the mechanical performance of the irregular box are analyzed, summarized how to arrange support beams of the girder bridge some beneficial conclusions are obtained, and may be available for use in irregular box girder engineering designs.