多线铁路桥梁的力学特性分析及优化设计

发布时间：2018-09-08 18:43

【摘要】：摘要：本文依托介西线孝义市区改线工程中的兑镇河一号特大桥为研究对象,通过查阅秦沈客专等桥梁设计相关资料,总结桥梁结构优化设计理论,初步选定6种桥梁结构方案对比分析。通过对上部结构、下部结构的优化设计,为该桥梁的设计、施工提供合理建议,本文主要进行了以下研究并得出相关结论： 1.主要对比分析各方案上部结构的力学性能,选出最优上部结构；在上部结构的静力分析中,通过建立全桥模型,主要计算6种方案在不同荷载工况下的静力指标,并与相关规范对比分析。对于上部整体式桥面结构,采用基于梁格法的空间结构分析方法。分析结果表明：添加预应力后,除考虑整体升温时整体式桥面结构在肋板处产生拉应力外,上部结构的力学参数均满足规范要求,整体式桥面的受力性能优于其它上部结构形式。 2.在下部结构的静力分析中,对三柱墩,通过墩柱截面、墩形的优化设计增加其整体刚度；通过MidasFEA实体建模分析薄壁空心墩的墩底应力分布,并对其空心段截面参数优化设计,对优化后的桥墩结构主要分析各荷载工况下墩身受力及墩顶位移,分析结果表明：优化后三柱墩的刚度仍然小于薄壁空心墩,三柱墩在铁路桥中不能发挥其特性优势,薄壁空心墩墩底实体段的长度影响墩底应力分布,减小截面尺后在桥墩实体过渡段出现较大的拉应力,其刚度仍可满足要求,在考虑降温温度梯度时,桥墩底部实体过渡段处有较大拉应力出现,在设计、施工时应该采取相应措施。 3.在动力分析中,主要讨论各方案的自振特性和反应谱分析。有限元计算结果表明：结构内力(预应力)对本文中的桥梁结构自振影响不大；参数优化后的三柱墩桥梁结构的自振频率仍远低于薄壁空心墩结构；在采用反应谱分析时,分析考虑地震荷载的各工况作用下的结构响应,得出顺桥向罕遇地震作用下的荷载组合为控制下部结构设计的最不利荷载。
[Abstract]:Abstract: Based on the Daizhenhe No.1 Bridge in Xiaoyi City of Jiexi Line, this paper summarizes the theory of optimum design of bridge structure by consulting the design data of Qinshen Passenger College and other bridges, and preliminarily selects six kinds of bridge structure schemes. Reasonable suggestions are provided for the design and construction.
1. Mainly compare and analyze the mechanical properties of the superstructure of each scheme, select the best superstructure; in the static analysis of the superstructure, through the establishment of the whole bridge model, mainly calculate the static index of six schemes under different load conditions, and compare with the relevant specifications. For the superstructure of the integral bridge deck, the method based on the girder grid is adopted. The results show that the mechanical parameters of the superstructure satisfy the requirements of the code, and the mechanical performance of the monolithic deck is superior to that of other superstructure forms.
2. In the static analysis of the substructure, the overall stiffness of the three-column pier is increased by optimizing the section of the pier and the shape of the pier; the stress distribution at the bottom of the thin-walled hollow pier is analyzed by the solid modeling of MidasFEA, and the section parameters of the hollow section are optimized. The stress of the pier under various load conditions and the stress of the pier body are mainly analyzed. The results show that the stiffness of the optimized three-column pier is still less than that of the thin-walled hollow pier, and the three-column pier can't give full play to its advantages in the railway bridge. The length of the solid segment at the bottom of the thin-walled hollow pier affects the stress distribution at the bottom of the pier, and the tensile stress at the transition section of the pier can still meet the requirements after reducing the section ruler. Considering the cooling temperature gradient, the large tensile stress occurs at the transition section of the solid at the bottom of the pier. Corresponding measures should be taken in the design and construction.
3. In the dynamic analysis, the natural vibration characteristics and response spectrum analysis are mainly discussed. The results of finite element analysis show that the internal force (prestress) of the structure has little effect on the natural vibration of the bridge structure in this paper; the natural vibration frequency of the three-column pier bridge structure after parameter optimization is still far lower than that of the thin-walled hollow pier structure; Based on the analysis of the structural response under various seismic loads, it is concluded that the load combination along the bridge under rare earthquake is the most unfavorable load to control the lower structure design.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U448.13;U441

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