Study On The Calculation Method Of Thin-walled Steel Box Girder

The thin-walled steel box girder had numerous advantages, such as good torsional stiffness, lateral bending stiffness, excellent wind resistance, etc. Therefore, it has been widely used in long-span cable-stayed bridges, suspension bridges, as well as arch bridges at present. This feature incurs that the behavior of thin walled steel box girder is too complex to be analyzed with classical calculational methods. No domestic criterions has prescripted a proximate calculational method available for this structure. It is useful to discuss the calculational methods of thin walled steel box girder, in terms of both theory and practice.A brief history of the development of thin walled steel bod girder structure in bridge engineering is reviewed. The anthor summarized the the calculational methods of thin walled box girder. For the big rate of width and span bridge,using grillage method can be simulated, and getting the whole structure of work performance.In order to investigate the feasibility and accuracy of grillage analogy method to the wide box grider, the single grider model, the grillage model as well as the shell element model are established, and the stress, displacement, shearing force, bending moment, torquemoment results from the three models are compared. The analytical results show that comparring with the single grider method, the results form the grillage analogy method are in good agreement with he shell element method and suitable for precisely describing the mechanical properties of the wide box grider, and the normal results from grillage analogy method are acceptable from an engineering design standpoint.The thesis building up the integrated finite element model of a cable-stayed bridge by the grillage simulation, considering the bridge structure,loading conditions, boundary conditions, etc. In the operational stage, the effect of the structure under combined live load and dead load is studied and analyzed, validating the stress and displacement of this bridge to the standard in the limit state. Using grillage method to analyze cable-stayed bridge is effective.With the general used finite element analysis software ANSYS,the spacial pole system finite element model,the mixing finite element model and segment finite element model were created to analyse the steel bix girder. Compared with segment finite element analysis method, and the stress superposition method, the whole structure analysis finite element method was sugguested to calculate thin walled steel box girder, because it is accurate. Using A.I.S.C. method and finite element method to study the third essential structure system respectively. By comparing the result of the two methods, it is easy to find that the calculation results are in a great difference at longitudinal. However the maximal transverse stress of the third essential structure system from A.I.S.C.method is quite close to the result of finite element method. Because of it's results include the stress of the second system partly, the results are not precise, though the finite element method can simulate the virtual structure.