【作者】 宋旭明；

【导师】 戴公连；

【作者基本信息】 中南大学 ， 桥梁与隧道工程， 2009， 博士

【摘要】 自锚式悬索桥以其结构新颖、造型优美、经济性能良好、对地形及地质状况适应性强等优点而越来越受到工程界的关注。自锚式悬索桥主缆锚固于主梁之上,形成纵向自平衡体系,其施工方法和成桥后的受力特性均与地锚式悬索桥有显著差别。本文以长沙市三汊矶湘江大桥为工程背景,对大跨度自锚式悬索桥的受力性能及局部与整体相关屈曲极限承载力进行研究,主要完成了以下工作:(1)将自锚式悬索桥钢箱梁离散为由边箱及顶底板组成的空间梁段单元。主梁中任一点的总位移为整体位移和局部位移之和,按平截面假定计算梁段单元整体位移,沿加劲梁纵向取单位长度横向条带计算单元的局部位移。基于有限变形理论及修正的拉格朗日列式,推导了自锚式悬索桥主梁局部与整体相关屈曲非线性增量平衡方程和单元刚度矩阵,并编制了相应的分析软件。(2)选择主梁及桥塔的拉压及弯曲应变能作为优化目标,吊索力作为设计变量,成桥线形作为状态变量,将优化计算理论引入自锚式悬索桥成桥状态的确定,为达到合理的成桥状态提供理论依据及实现途径。结合索段数值分析和非线性有限元的特点,提出自锚式悬索桥主缆线形和无应力索长计算的迭代方法,编制了相应的计算程序。(3)详细探讨了跨径布置、主缆矢跨比、主梁上拱度、吊索间距、主梁抗弯刚度以及主缆轴向刚度等结构参数对自锚式悬索桥受力性能的影响。通过目标函数对设计变量的梯度值,引入结构参数敏感系数,并对成桥线形、结构竖向刚度、主梁及塔底弯矩的参数敏感系数进行计算,为结构设计及施工控制提供依据。(4)对三汊矶湘江大桥进行了1:28的整体模型试验,利用结构优化理论对模型试验的施工过程进行控制,获得了合理的成桥状态。表明吊索的无应力安装能够应用于实际工程,避免了反复张拉吊索的过程,提高了施工效率。成桥阶段受力性能实测结果与计算值吻合良好,验证了计算理论和分析程序的可靠性。(5)利用编制的分析程序计算了三汊矶湘江大桥在不同荷载工况下的局部与整体相关屈曲极限承载力,并探讨了主梁横隔板刚度、间距及局部变形对自锚式悬索桥局部与整体相关屈曲极限承载力的影响。(6)对三汊矶湘江大桥设计过程中结构体系的选择、成桥状态的优化、施工过程中的受力状态以及结构地震响应和减震控制措施进行分析计算,为结构设计参数的选择提供依据。更多还原

【Abstract】 The self-anchored suspension bridge, with its unique structure, beautiful appearance, good economic performance as well as the advantages of the strong adaptability to the terrain and geological conditions, is attracting increasingly more attention in engineering. It forms a longitudinal self-balancing system with the main cable anchored on the stiffened girder. Hence, the self-anchored suspension bridge is different in construction methods and mechanical characteristics from the land-anchored suspension bridge. Based on the study of the SanChaJi Xiangjiang Bridge, this dissertation attempts to analyze the mechanical -characteristics and the local-overall interactive buckling ultimate carrying capacity of the long span self-anchored suspension bridge. The main contents are as follows:(1) A spatial beam element is established for the calculation of self-anchored suspension bridge’s ultimate carrying capacity with local-overall interactive buckling is considered. The displacements of any element are composed of the overall displacement and the local displacement. The overall displacement is calculated based on the plane-section assumption, and the local displacement is derived through a unit length of transverse segment in longitudinal direction of the stiffened girder. Based on the finite deformation theory and the U.L. formulation, the incremental equations and the element stiffness matrices of the self-anchored suspension bridge with local-overall interactive buckling are established. The calculation program is also developed.(2) The structural optimization theory is used in the determination of the finished state of the self-anchored suspension bridge. The tension-compression and bending strain energy of stiffened girder and pylons is chosen as the objective function. The hanger force is taken as design variables and the girder shape in finished state is selected as state variables. Combining the numerical analysis and the nonlinear finite element method, this dissertation proposes an iterative method for calculating the shape and unstressed length of the main cable of the self-anchored suspension bridge. The corresponding calculation program is also developed.(3) The parameters which produce effects on mechanical behaviors of the self-anchored suspension bridge were discussed, including the span arrangement, the ratio of sag to span, the main girder shape, the hanger spacing, the main girder bending stiffness and the axial stiffness of the main cable. Using the gradient value of objective function to the design variables, the sensitive coefficient of structural parameters is introduced. The sensitive coefficients of the bridge shape, structural stiffness, moment in main girder and pylon bottom are calculated. They can be a reference for structure design and construction control.(4) A model test with the scale 1:28 is carried out to validate the process of construction and calculation method. The designed finished state of the model test is obtained by controlling the process of construction using optimization theory. It indicates that the method of unstrained installation of hangers can be used in practice, and the construction efficiency is improved. The measured results agree well with the calculated values under live load, and the validity of calculation theory and program is verified.(5) The ultimate loads of SanChaJi Xiangjiang Bridge with the local-overall interactive buckling under different load conditions are analyzed. The factors that affect the ultimate loads such as the cross beam spacing, stiffness and local deformation of main girder are discussed.(6) The selection of structure system, optimal calculation of finished state, mechanic state in the construction stage, seismic response and control of SanChaJi Xiangjiang Bridge are analyzed in this dissertation. The results are provided as a reference for structure design.更多还原