横撑对钢管混凝土桁肋拱面外稳定性能的影响

发布时间：2019-02-18 22:56

【摘要】：钢管混凝土桁肋拱常在大跨度拱桥设计中应用,其桁肋拱是由弦杆和缀杆或者钢板所组成,相对于钢筋混凝土材料、单圆管和哑铃型截面来说,其拥有较高的截面效率。桁肋拱是由横撑将两拱肋联系在一起,以确保其横向稳定性,故研究横撑对钢管混凝土桁肋拱面外稳定性的影响具有重要的理论意义和工程价值。本文介绍了钢管混凝土结构的概况和发展,列出了一部分国内外研究者在钢管混凝土桁式拱桥稳定性方面的研究成果,从中简要介绍了关于钢管混凝土拱肋弹性稳定性和极限承载力的理论与方法。其中,对钢管混凝土拱桥的弹性稳定性分析研究所占比例较大,极限承载力的分析研究较小；利用软件分析钢管混凝土拱肋稳定性的研究较多,建立实际模型拱肋并研究的较少。这使得钢管混凝土桁肋拱的设计参数还要继续深入探讨。本文以自行设计的钢管混凝土桁肋拱为研究对象,利用ANSYS有限元分析软件建立该拱肋的空间有限元模型,分析了该拱肋的失稳模态、弹性稳定系数和进行了考虑其材料非线性与几何非线性的极限承载力研究。探讨了横撑的布置形式、横撑的样式和横撑的刚度对钢管混凝土桁肋拱面外稳定性能的影响,结论如下：(1)在拱桥设计时应尽量选择合适的横撑数量和横撑间距,可以提高钢管混凝土桁肋拱的面外稳定性。(2)拱肋在四分点处的相对搓动较大,因此应该在四分点处设置强大的横撑。并尽量避免横撑最大间距落在四分点处,使拱肋弹性稳定性降低。(3)在拱顶应设置一道横撑,这可使拱肋的横向联系增强,增加弹性稳定性。而且,拱顶横撑选择“一”字型横撑足以,既可保证弹性稳定,又可降低自重和简便横撑施工工序。(4)横撑的不同样式中,“米”字型和“X”字型横撑能使拱肋得到更高的弹性稳定系数。端部横撑则使用“K”字型横撑会较容易达到桥面净空要求,而且拱肋的弹性稳定不会降低。(5)横撑的刚度对拱肋的弹性稳定性影响不太明显,在设计中选择适当的钢管壁厚既保证不发生局部失稳即可,又可以减轻自重。(6)通过采用千分之一的初始缺陷的极限承载力分析所得的结果显示,横撑对钢管混凝土桁肋拱的极限承载力的影响与对其弹性稳定性的影响基本相同。(7)钢管混凝土桁肋拱的极限承载力系数要比弹性稳定系数小,各模型所得系数均相差15%左右,即说明在考虑钢管混凝土桁肋拱稳定性问题的时候,既要进行弹性稳定分析,又要考虑到其极限承载力系数的问题,二者缺一不可。
[Abstract]:Concrete filled steel tube truss rib arch is often used in the design of long-span arch bridge. Its truss rib arch is composed of chord, affix bar or steel plate. Compared with reinforced concrete material, single circular tube and dumbbell section, it has high cross-section efficiency. Truss rib arch is connected by transverse braces to ensure its lateral stability, so it is of great theoretical significance and engineering value to study the influence of transverse bracing on the out-of-plane stability of concrete-filled steel tubular truss rib arch. This paper introduces the general situation and development of concrete-filled steel tubular (CFST) structures, and lists some domestic and foreign research achievements on the stability of CFST truss arch bridges. The theory and method of elastic stability and ultimate bearing capacity of concrete-filled steel tubular arch rib are briefly introduced. Among them, the research on the elastic stability of concrete-filled steel tubular arch bridge accounts for a large proportion, the ultimate bearing capacity analysis and research is small; The stability of concrete-filled steel tubular arch rib is analyzed by software. This makes the design parameters of CFST truss rib arch to be further discussed. In this paper, the spatial finite element model of concrete filled steel tubular truss rib arch is established by using ANSYS finite element analysis software, and the instability mode of the arch rib is analyzed. The elastic stability coefficient and the ultimate bearing capacity considering the material nonlinearity and geometric nonlinearity are studied. The effects of the arrangement of transverse brace, the style of transverse brace and the stiffness of transverse brace on the stability of concrete-filled steel tubular truss rib arch are discussed. The conclusions are as follows: (1) when designing arch bridge, the appropriate number and spacing of transverse brace should be selected as far as possible. It can improve the out-of-plane stability of concrete-filled steel tube arch with truss ribs. (2) the relative rubbing of arch ribs at four points is relatively large, so strong transverse braces should be set at four points. As far as possible, the maximum spacing of transverse braces should be avoided at four points to reduce the elastic stability of arch ribs. (3) A transverse brace should be set at the top of the arch, which can strengthen the transverse connection of arch ribs and increase the elastic stability. Moreover, the choice of "one" type crossbrace is enough to ensure the stability of elasticity and reduce the weight and convenience of the construction process. (4) in the different types of crossbrace, The cross-bracing of meter and X-type can increase the elastic stability coefficient of arch rib. On the other hand, the "K" transverse brace can easily meet the bridge floor clearance requirement, and the elastic stability of arch rib will not be reduced. (5) the stiffness of transverse brace has little effect on the elastic stability of arch rib. In the design, the proper thickness of the steel pipe wall can not only ensure that there will be no local instability, but also reduce the weight of the steel pipe. (6) through the analysis of the ultimate bearing capacity of the initial defect of 1/1000, the results show that, The influence of transverse brace on ultimate bearing capacity of CFST truss rib arch is basically the same as that on its elastic stability. (7) the ultimate bearing capacity coefficient of CFST truss rib arch is smaller than that of elastic stability factor. The difference of the coefficients of each model is about 15%, that is, when considering the stability of concrete-filled steel tubular truss rib arch, it is necessary to carry out elastic stability analysis as well as to consider the ultimate bearing capacity coefficient.
【学位授予单位】：沈阳建筑大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U448.22;U442.5

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