公铁两用斜拉桥索梁锚固结构疲劳性能与疲劳寿命研究

发布时间：2018-05-03 19:22

  本文选题：索梁锚固结构 + 钢桥疲劳　； 参考：《北京交通大学》2017年博士论文

【摘要】：近年来,为了满足公路和铁路共用桥位的需求,公铁两用斜拉桥得到了广泛的应用。在汽车荷载和列车荷载的共同作用下,大跨度公铁两用斜拉桥承受了巨大的荷载作用。作为斜拉桥中拉索和主梁的连接构件,索梁锚固结构具有复杂的局部焊接构造,此外,在传递巨大的荷载效应过程中,索梁锚固结构应力集中现象突出。为了解决这一问题,在现有公铁两用斜拉桥中采用了一种连接拉索和钢桁梁的新型索梁锚固结构形式—复合式双锚拉板锚箱。双侧锚拉板作为传力竖板,上部通过焊接构成锚箱,与拉索锚固连接,下部与主梁顶板连接。在汽车荷载和列车荷载的组合作用下,作用在索梁锚固结构上的荷载通过连接焊缝传递,焊接细节的疲劳问题十分突出。本文对复合式双锚拉板锚箱开展了系统的研究,以边界等效的疲劳试验为基础,分别采用名义应力、热点应力以及断裂力学方法研究了索锚结构的疲劳性能;结合累积损伤模型和裂纹扩展模型中的参数特征,采用疲劳寿命分析的混合可靠度模型,对索梁锚固结构的疲劳寿命进行了研究。研究内容如下:(1)回顾公铁两用斜拉桥的建造和发展,分析了索梁锚固结构的受力特征和结构组成特征,结合既有钢桥的疲劳病害情况,论述了公铁两用斜拉桥索梁锚固结构中的疲劳问题及其研究的必要性,综述了索梁锚固结构疲劳性能和疲劳寿命的研究现状,说明了论文研究的意义。(2)采用既有公路汽车和铁路列车的疲劳车模型,通过数值模拟研究了斜拉桥的索梁锚固结构的疲劳荷载及其组合方法。研究了索梁锚固结构疲劳细节的应力分布特征,以及各板件的几何参数敏感性,得到了复合式双锚拉板锚箱的基本结构和三类疲劳敏感细节,分别为锚压板与传力竖板连接端部轴拉细节、锚压板与传力竖板连接侧面拉剪细节,以及锚压板承压端部的压剪细节,并给出相应名义应力幅计算公式。(3)基于相似原理,考虑应力等效和边界等效,开展了复合式双锚拉板锚箱基本结构的疲劳试验。初始状态下的静力加载测试表明:基本结构的实测应力分布与有限元计算值基本吻合,基本结构与实际索梁锚固结构中的有限元计算值具有较高的一致性,可以用于索梁锚固结构疲劳性能研究。疲劳试验表明:索梁锚固结构在轴拉细节和压剪细节位置观测到裂纹,轴拉细节的疲劳断裂导致了索梁锚固结构的整体失效;轴拉细节疲劳性能与锚压板宽高比有关,结合规范中相关的S-N曲线,引入与锚压板宽高比相关的参数,对轴拉细节名义应力幅计算公式进行修正;并给出了各细节的参考疲劳细节类别。(4)采用热点应力外推法,对索梁锚固结构中的不同应力状态下的疲劳细节进行热点应力判定,采用有限元模拟,分析了单元类型、网格尺寸以及外推方法对热点应力的影响。结合试验中轴拉细节的热点应力测试值,验证了有限元模拟的有效性,以及FAT90曲线在索梁锚固结构疲劳寿命分析中的合理性。采用应力集中系数,对基本结构中的几何参数进行敏感性分析,结合实桥中几何参数的取值规律,给出轴拉细节和拉剪细节应力集中系数的表达式。(5)采用线弹性断裂理论研究裂纹扩展规律,借助ANSYS与FRANC3D有限元软件,对裂纹尖端的应力强度因子和裂纹扩展进行模拟分析,借助文献中穿透型裂纹和半椭圆表面裂纹的试验测试值,验证有限元模拟的有效性。采用最大周向应力准则对承压板与传力竖板连接端部裂纹进行裂纹扩展模拟,结合断口形貌,研究了初始裂纹尺寸和形状对裂纹尖端应力强度因子和裂纹扩展的影响。采用应力强度因子修正系数,对基本结构中的几何参数进行敏感性分析,给出锚压板与传力竖板连接端部半椭圆裂纹的应力强度因子修正系数的表达式。(6)传统的钢结构疲劳寿命预测误差较大,线性累积损伤模型和裂纹扩展模型中变量具有不确定性和随机性,基于区间-概率理论,分别推导了服从正态分布、对数正态分布的概率模型和区间模型的一致性关系,给出可同时考虑区间变量和随机变量的混合可靠度理论简化分析模型和求解方法。对桥梁工字梁中的疲劳细节进行疲劳寿命分析,验证本文方法的有效性和适用范围。采用累积损伤模型和裂纹扩展模型对索梁锚固结构的轴拉细节进行疲劳可靠性研究,分析索锚结构的疲劳寿命,给出了设定合理检修周期的建议。
[Abstract]:In recent years, in order to meet the needs of highway and railway common bridge position, the dual-purpose cable-stayed bridge has been widely used. Under the joint action of vehicle load and train load, the long-span steel and iron dual use cable-stayed bridge bears great load. As the connecting member of the cable and the main beam in the cable-stayed bridge, the cable girder anchorage structure is complex. In addition, the stress concentration of cable girder anchorage structure is prominent during the process of transferring huge load effect. In order to solve this problem, a new type of cable beam anchorage structure, a double anchor plate anchor box, is adopted in the existing dual-purpose cable-stayed bridge with cable and steel truss. The vertical plate is connected with the cable anchorage and the bottom is connected with the cable roof. Under the combined action of the vehicle load and the train load, the load on the cable beam anchorage structure is passed through the welding seam, and the fatigue problem of the welding details is very prominent. On the basis of the boundary equivalent fatigue test, the fatigue performance of cable anchor structure is studied by nominal stress, hot stress and fracture mechanics, and the fatigue life of cable beam anchorage structure is carried out by combining the cumulative damage model and the parameter characteristics of the crack propagation model and the fatigue life analysis. The research contents are as follows: (1) review the construction and development of the dual-purpose cable-stayed bridge, analyze the characteristics of the stress and structure of the cable girder anchorage structure, and combine the fatigue disease of the existing steel bridge, discuss the fatigue problem and the necessity of the study in the cable girder anchorage structure of the dual-purpose cable-stayed bridge, and summarize the consolidation of the cable girder anchorage. The research status of structure fatigue and fatigue life shows the significance of the thesis. (2) fatigue load and combination method of cable girder anchorage structure of cable-stayed bridge are studied by numerical simulation, and the stress distribution characteristics of cable girder anchorage structure are studied by numerical simulation, and the stress distribution characteristics of cable girder anchorage structure are studied. The geometric parameter sensitivity of the plate is obtained. The basic structure and three kinds of fatigue sensitive details of the composite double anchorage plate anchor box are obtained, which are the details of the end of the anchor plate and the force vertical plate, the details of the lateral tension of the anchorage plate and the force vertical plate, and the pressure shear details of the pressure end of the anchor plate, and the corresponding nominal stress amplitude is calculated. (3) based on the similarity principle and considering the stress equivalence and the boundary equivalence, the fatigue test of the basic structure of the composite double anchor plate anchorage box is carried out. The static loading test under the initial state shows that the measured stress distribution of the basic structure is basically consistent with the calculated value of the finite element, and the basic structure and the finite element calculation value of the actual cable beam anchorage structure are calculated. It has high consistency and can be used to study the fatigue performance of cable beam anchorage structure. Fatigue tests show that the cable girder anchorage structure observates cracks in the detail of axial tension and pressure shear detail, and the fatigue fracture of axial tension leads to the overall failure of the cable beam anchorage structure, and the fatigue performance of axial tension is related to the width to height ratio of the anchor plate, and is combined with the specification. The relevant S-N curve and the parameters related to the ratio of the width to height of the anchor plate are introduced, and the formulas for calculating the nominal stress amplitude of the axial tension are corrected. And the reference fatigue details of each detail are given. (4) the hot stress extrapolation method is adopted to determine the hot stress of the fatigue details under different stress states in the cable beam anchorage structure. The effect of the element type, grid size and extrapolation method on the hot stress is analyzed. The validity of the finite element simulation and the rationality of the FAT90 curve in the fatigue life analysis of the cable beam anchorage structure are verified by combining the hot stress test values of the axial tension in the test. The stress concentration coefficient is used for the basic structure. The sensitivity analysis of geometric parameters is carried out and the expression of the stress concentration coefficient of the axial tension and shear details is given. (5) the law of crack propagation is studied by the linear elastic fracture theory, and the stress intensity factor and crack propagation at the crack tip are simulated with the help of ANSYS and FRANC3D finite element software. The validity of the finite element simulation is verified by the test test values of the penetrable crack and semi elliptical surface crack in the literature. The crack propagation of the end cracks of the pressure plate and the force vertical plate is simulated by the maximum circumferential stress criterion, and the stress intensity factors of the crack tip are studied with the fracture morphology and the initial crack size and shape. The stress intensity factor correction coefficient is used to analyze the sensitivity of the geometric parameters in the basic structure. The expression of the stress intensity factor correction factor of the semi elliptical crack at the end of the anchor plate and the force vertical plate is given. (6) the fatigue life prediction error of the traditional steel structure is larger, and the linear cumulative damage model is used. The variables in the crack propagation model have uncertainty and randomness. Based on the interval probability theory, the consistency relation between the probability model and the interval model is derived, which obeys the normal distribution and the logarithmic normal distribution, and the simplified analysis model and the solution method, which can simultaneously consider the interval variable and the random variable, are given. The fatigue life analysis is carried out in the girder of the beam structure, and the validity and application range of this method are verified. The fatigue reliability of the axial tension details of the cable girder anchorage structure is studied by the cumulative damage model and the crack propagation model, and the fatigue life of the cable anchor structure is analyzed, and some suggestions for setting the reasonable maintenance period are given.

【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：U448.27
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本文编号：1839764