正交异性钢桥面板U肋弧形切口疲劳受力特性研究

发布时间：2018-11-26 10:38

【摘要】：目前,悬索桥和斜拉桥是大跨径桥梁的主要桥型,钢箱梁是大跨径桥梁最主要的桥面结构体系。现在钢箱梁大部分都采用的是正交异性钢桥面板结构,正交异性钢桥面板是由纵、横向相互之间垂直的加劲肋,并连同桥面板组成的共同承受车轮荷载的整体结构。它拥有一系列的优点,例如自重轻、用料省、极限承载力大、施工周期短,因此,如今该结构形式的的桥面板结构常常作为钢箱梁的一部分被广泛用于大跨径桥梁的建造中。随着我国高速公路和铁路的高速发展,正交异性钢桥面板凭借其优越的结构形式在公路桥梁和铁路桥梁中得到广泛的运用。但是由于正交异性钢桥面板受力比较复杂,而且其构造形式不断改进和发展,同时随着应力集中和焊接缺陷的出现,容易发生疲劳破坏,如桥面板在各类车辆荷载的反复作用下会引起累积损伤;钢桥面板因为直接承受车辆的局部作用,而使得应力影响线短,一辆车行驶过后都会引起多次的应力循环,再加上焊接处的应力集中以及焊接缺陷,钢桥面板很容易发生疲劳开裂。因此正交异性钢桥面板的疲劳问题长期以来一直是公路和铁路桥梁中的关键问题。世界上一些较早应用钢桥面板的国家如日本、德国、法国、英国等已经在目前运营中的实桥中发现了疲劳裂纹。世界各国研究者针对钢桥的疲劳破坏实例进行了广泛深入的研究,结果表明对钢桥特别是正交异性钢桥面板进行疲劳验算是一项很关键的任务。它包含了正交异性钢桥面板的应力计算、结构分析、疲劳强度、疲劳验算方法以及车辆荷载谱等核心问题。本文采用ANSYS大型通用有限元软件对钢箱梁正交异性钢桥面板进行了数值模拟,对弧形切口形状、顶板厚度、横隔板厚度等关键参数进行了分析,研究了横隔板与U肋焊缝交叉处的应力状态。结果表明:过焊孔的形状对应力的影响显著,顶板对焊缝交叉处的应力影响较小,横隔板厚度对疲劳裂纹的产生有较大的影响。通过对过焊孔焊缝端部和焊孔边缘应力分布情况的分析,采用Miner线性累积损伤准则,计算了各关注点的等效应力幅,通过比较发现,对于过焊孔焊缝端部,公路标准比铁路标准的等效应力幅大;对于过焊孔焊缝边缘,则恰恰相反。另外,本文针对过焊孔焊缝端部的应力集中现象采取了措施,通过优化过焊孔的构造能有效地缓解该处的应力集中情况。
[Abstract]:At present, suspension bridge and cable-stayed bridge are the main type of long span bridge, and steel box girder is the main deck structure system of long span bridge. Now most of the steel box girders are orthotropic steel bridge panel structure, orthotropic steel bridge panel is composed of longitudinal, transverse vertical stiffening ribs, and together with the bridge deck plate to bear the wheel load of the whole structure. It has a series of advantages, such as light weight, less material, large ultimate bearing capacity and short construction period. Therefore, the deck slab structure of this structure is widely used in the construction of long-span bridges as a part of steel box girder. With the rapid development of highway and railway in our country, orthotropic steel bridge face is widely used in highway bridge and railway bridge by virtue of its superior structural form. However, due to the complexity of the stress on orthotropic steel bridge face, and the continuous improvement and development of its structural form, along with the stress concentration and the appearance of welding defects, fatigue failure is easy to occur. For example, the bridge deck will cause cumulative damage under the repeated action of various vehicle loads. Because the steel bridge face plate is directly subjected to the local action of the vehicle, the stress effect line is short. After a vehicle is driven, it will cause many stress cycles, plus the stress concentration in the welding place and the welding defects. Steel bridge panels are prone to fatigue cracking. Therefore, the fatigue problem of orthotropic steel bridge panels has been a key problem in highway and railway bridges for a long time. Fatigue cracks have been found in existing bridges in countries such as Japan, Germany, France and the United Kingdom, which used steel bridge panels earlier. Researchers all over the world have carried out extensive and in-depth research on fatigue failure examples of steel bridges. The results show that fatigue checking of steel bridges, especially orthotropic steel bridge panels, is a key task. It includes the stress calculation, structural analysis, fatigue strength, fatigue checking method and vehicle load spectrum of orthotropic steel bridge panel. In this paper, the finite element software ANSYS is used to simulate the plate of orthotropic steel bridge of steel box girder, and the key parameters, such as the shape of arc notch, the thickness of roof and the thickness of transverse partition, are analyzed. In this paper, the stress state of the cross weld between transverse diaphragm and U rib is studied. The results show that the shape of the overwelded hole has a significant effect on the stress, the roof has little effect on the stress at the weld seam intersection, and the thickness of the transverse diaphragm has a great effect on the fatigue crack. Based on the analysis of the stress distribution at the weld end and the edge of the overwelded hole, the equivalent stress amplitude of each concerned point is calculated by using the Miner linear cumulative damage criterion. Through comparison, it is found that, for the weld end of the overwelded hole, The equivalent stress amplitude of highway standard is larger than that of railway standard. The opposite is true for weld edges of overwelded holes. In addition, some measures have been taken to improve the stress concentration at the weld end of the overwelded hole, and the stress concentration can be effectively alleviated by optimizing the structure of the overwelded hole.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441.4;U443.31

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