【作者】 李鑫奎；

【导师】 杨刚；

【作者基本信息】 大连海事大学 ， 道路与铁道工程， 2008， 硕士

【摘要】 桥梁优化问题已经成为桥梁科技发展的前沿课题,尽管优化设计在机械等领域取得了较大成果,但由于桥梁自身结构特点的限制使得桥梁优化设计发展较为缓慢,实际应用较少。以往的桥梁设计都是满足规范要求的最初等设计,这种设计既不能描述和处理桥梁结构中客观存在的各种不确定性因素,更无法科学的协调他们之间的矛盾,使它们达到合理的平衡,因此有必要重视优化设计在桥梁中的应用。论文搜集了大量有关桥梁优化设计、可靠性分析等方面的文献,借鉴了现有的最新科研成果,同时结合ANSYS有限元分析软件对桁架桥进行了考虑可靠度的优化设计分析研究,本文主要对以下五个方面进行了研究分析。1.结合钢桁架桥的特点,建立钢桁架桥有限元模型,对钢桁架桥进行加载模拟,分析桥梁受力特性及应力分布,从而为以后的优化设计奠定基础。2.结合ANSYS有限元分析软件中的优化分析功能对钢桁架桥进行以桥梁结构中最大应力和最大挠度为约束条件,以截面尺寸为设计变量,以全桥自重为目标函数的优化分析,对于优化结果进行局部稳定性、整体稳定性验算,对于不满足要求的截面尺寸进行调整,最终确定桁架桥截面尺寸。3.对优化后的钢桁架桥进行可靠度计算,分析在汽车荷载下桥梁体系的可靠性。同时对钢桁架桥体系可靠度进行灵敏度分析,确定各个截面尺寸对桥梁可靠性的影响程度。4.结合对钢桁架桥可靠度的灵敏度分析,对桥梁进行优化设计,实现基于可靠性的桥梁优化设计。5.针对当前桁架桥破坏的特点,提出了用复合材料替代结构中薄弱杆件,从而达到提高桥梁承载力的目的,并对提高的具体数值进行了计算和分析。更多还原

【Abstract】 Bridge optimization has became the newest subject of bridge technology. Although optimized design in the fields of mechanical been widely applied, but because of the restrictions of bridge engineering make bridge optimization design developed slowly and applied less in practice.At present the bridge are designed to meet regulatory requirements, which can not describe and handle the existence of various uncertain factors, expecialy not coordination of the contradictions between those factors scientific, making they achieve a reasonable balance. So it is necessary to pay more attention in the bridge optimization.In the process of writing this paper Author collected a large amount of design optimization and reliability analysis literatures,then Calculated truss bridge with ANSYS software based on reliability theory.The main work as following.First. Establishment of steel truss bridge finite element model. Then on the steel truss bridge for loading simulation .Analysis of the characteristics of the bridge and the stress distribution, so as to lay the foundation for the design optimization..Second. Using the optimization function of ANSYS software optimizes the bridge on the basis of the maximal stress and deflection taken as the constrained condition, the sectional dimension of tress taken as designed variables and the volume of steel taken as the objective function. Furthermore checking the Optimization results for the local stability and overall stability,then Adjustments section size which are not satisfied the requirements, and ultimately determines them.Third. Calculat the results after optimized, Analysis of the system reliability of bridge under the vehicle load.The results show that this bridge has a sufficiently high reliability.Then Calculat the system reliability sensitivity to determine the degree of influence on the reliability Of the size of each section .Forth. Optimal design of the bridge based on the reliability of sensitivity analysis,achieve optimization based on the reliability. Fifth. In view of the current truss bridge damage characteristics,By using composite material Replacement the weak bar, so as to achieve the purpose of enhancing carrying capacity bridges, And calculat and analysis the specific numerical of improvement.更多还原