Stability Study On Tower Frame Of Runyang Yangtze River Bridge

The thesis presents the current research situations of nonlinear study on the steel frame system, as well as the research history of the stability of compressed bars. In addition, the research methods for the global stability of steel frames are introduced in the thesis, which involves the treatments of many nonlinear factors influencing the global stability of steel frames. All mentioned above are given brief descriptions.Steel tower frame of the Southern Runyang Yangtze River Suspension Bridge is taken as engineering background in this thesis, and ANSYS general finite element program is used to set up the space analysis model. Then elastic buckling models are analyzed in different load cases and at different stages. And then, the former two buckling models of structural elastic buckling ones are extracted. Accordingly, the most critical load case in different construction conditions is found out, which is applied to the following structural nonlinear , analyses.In the course of structural nonlinear analyses, the thesis mainly analyzes the P-delta effects on the structural ultimate capacity, namely, the effects exerted by the initial defects including the initial curvature of main members and top displacement of steel frame etc on the structural ultimate capacity. And the thesis finds out the most critical members during the process of structural buckling, checks the strength of structural members and the stability of compressed members according to the specifications. Through the nonlinear analyses and comparison, the thesis draws a conclusion how the nonlinear stability varies under the initial defects including the influence of the initial curvature of main members and top displacement of steel frame etc. At the same time, it is effective to strengthen the stiffness of the first buckling member to enhance the global structural ultimate capacity.