Research On Design Method Of Thin-Walled Steel Box Girder

High strength thin-walled steel box adopts high-strength materials. The components are light and easy for transportation and installation. Thus, in recent years, it becomes the ideal bridge type for long-span bridge. However, for the steel box girder design, the stability problem is a significant problem. So the optimum design of steel box girder are concerned by engineers. So, in this dissertation, it studied the design of elastic stability of the thin-walled steel box. the main work has been done are as followings.(1) Design and the principle theory of elasticity for thin-walled steel box girder are summarized. It also studied the behavior and stability of flange and web. The focus is put on the stability of stiffened compression flange and stiffented web. For the web, it studied from the aspects of pure shear, pure bending and shear-bending interaction.(2) It introduced and compared the codes from different countries on the elastic stability of steel box girder design. In this study, more attentions were paid on the elastic design of stiffened rib.(3) Using finite element analysis program Ansys, models were made according to the critical parameters on the critical buckling stress of the thin-walled member. The comparison were conducted on the two methods:one is to increase the thickness of plates and another one is to set stiffened rib., The buckling problems of stiffened plate with the longitudinal stiffened ribs are also studied. Models with different parameters such as stiffness of stiffened rib, length-width ratio, stiffener spacing are created to find the buckling laws of stiffened plates.(4) The flexible design methods about the thin-walled steel box girder were proposed, especially for the flexible design of stiffened plates with open I-rigid stiffened rib. The corresponding finite element models were established and checked the proposed methods.It should be noticed that there are some limitations in the proposed methods on the design of stiffenned plates. The accuracy is more satisfied when the length-width ratio is appropriate. So the methods proposed in this thesis only provide a reference for the elastic design of stiffenned plates.