【作者】 岳振民；

【导师】 沈锐利；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2003， 硕士

【摘要】 本文简要回顾了压杆稳定问题的研究历程和钢结构框架体系非线性研究现状，介绍了钢结构框架整体稳定性研究的方法以及若干非线性因素的处理方法，并进行了简要评述。 本文以润扬长江大桥南汊悬索桥塔顶门架为工程背景，采用ANSYS通用有限元程序，建立了结构空间分析模型，对其在不同工况、不同阶段下的弹性屈曲失稳模式进行了分析，提取了结构弹性屈曲失稳的前二阶失稳模式，找出了该门架在悬索桥不同施工阶段的最不利荷载工况以进行后续的结构非线性分析。 在结构的非线性分析中，着重分析了结构P—delta效应对结构极限承载力的影响，即主要构件初曲率、框架顶部侧移等初始缺陷对结构整体极限承载力的影响，找出了结构失稳时的最不利构件，并考察了结构构件的强度，同时按规范规定验算了受压构件的稳定性。经计算比较分析，得出了结构在主要构件初曲率、框架顶部侧移等初始缺陷影响下结构非线性稳定性的变化规律。同时，加强结构中最先屈曲构件的刚度可以有效提高结构整体极限承载力。更多还原

【Abstract】 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.更多还原