正交异性钢桥面板U肋—横隔板构造细节的疲劳性能研究

发布时间：2018-12-16 03:53

【摘要】：正交异性钢桥面板因具有自重轻、施工便捷等优点,被广泛应用于各种类型的桥梁中。然而正交异性钢桥面板受力复杂,加之通行桥梁的车辆超载严重,各种焊接细节易出现疲劳开裂。研究车辆活载作用下的正交异性钢桥面板受力行为,分析构造细节的疲劳开裂机理,提出更为合理的正交异性钢桥面板构造设计,对桥梁的运营安全和耐久性显得尤为重要。论文从评价方法和实例分析两方面着手,讨论了正交异性钢桥面U肋-横隔板构造细节处的疲劳应力。主要研究内容和取得的成果如下:(1)介绍了正交异性钢桥面板的工程应用和疲劳开裂问题,回溯了疲劳的相关研究和实际钢桥的健康检测,并提出了本文的研究内容。(2)分别概述了名义应力法、热点应力法、零点结构应力法、缺口应变法及基于线弹性断裂力学的原理、使用条件、计算方法以及相对应的规范标准。另外,着重指出了上述方法存在的优缺点。(3)采用有效缺口应力法并以十字角焊缝为参考,分别计算单元类型、网格大小、焊根区域的网格划分方式对有效缺口应力的影响。结果表明:为避免解锁现象,有效缺口应力法计算时尽量使用高阶单元;网格大小必须满足IIW规定的最小要求,且无需过细划分导致工作量增加;当荷载平行于缺口时,可采用钥匙孔或U型孔建模;当荷载垂直于缺口时,应采用钥匙孔建模。(4)以某工程试验为例,分别采用热点应力法和有效缺口应力法计算关键点处的疲劳应力。结果表明有效缺口应力法可以适用于正交异性桥面板的疲劳评价,且比热点应力法具有一定的优越性。文章比较两种不同的横隔板过渡形式的有效缺口应力,得到了更加合理的方案;U肋-横隔板弧形切口焊趾处的有效缺口应力显著大于焊根处,证明焊趾处更易萌生裂纹;比较不同的U肋厚度,发现U肋厚度的增加会导致U肋-横隔板弧形切口焊缝处疲劳强度的降低。(5)现场实测某桥的应力时程曲线,采用雨流计数法、Miner准则并结合AASHTO规范条文计算正交异性钢桥面板典型易开裂处焊缝的等效应力幅,给出了疲劳寿命的估算值。结果表明:U肋-横隔板弧形切口焊缝处,靠近U肋侧和靠近横隔板侧疲劳寿命均不满足规范要求。该处疲劳开裂的原因是焊缝未打磨处理,导致焊缝质量降低。
[Abstract]:Orthotropic steel bridge face is widely used in various types of bridges because of its advantages of light weight and convenient construction. However, the orthotropic steel bridge face is complicated, and the vehicle overloading of the bridge is serious, so various welding details are prone to fatigue cracking. It is very important for the operation safety and durability of orthotropic steel bridge to study the stress behavior of orthotropic steel bridge slab under the action of live load, analyze the fatigue cracking mechanism of structural details, and put forward a more reasonable structural design of orthotropic steel bridge slab. In this paper, the fatigue stress of orthotropic steel deck U rib-transverse partition is discussed from two aspects of evaluation method and example analysis. The main research contents and achievements are as follows: (1) the engineering application and fatigue cracking of orthotropic steel bridge face are introduced. The research contents of this paper are also presented. (2) the nominal stress method, the hot spot stress method, the zero point structure stress method, the notch strain method and the principle and conditions based on linear elastic fracture mechanics are summarized respectively. Calculation method and corresponding specification standard. In addition, the advantages and disadvantages of the above methods are emphatically pointed out. (3) the effective notch stress method and the cross-fillet weld are used to calculate the cell type and mesh size, respectively. The effect of mesh generation on effective notch stress in soldering root region. The results show that, in order to avoid the unlocking phenomenon, the high-order element is used in the effective notch stress method, the mesh size must meet the minimum requirement of IIW, and the workload is increased without too much division. When the load is parallel to the notch, the model of keyhole or U-hole can be used. When the load is perpendicular to the notch, the keyhole model should be adopted. (4) the hot spot stress method and the effective notch stress method are used to calculate the fatigue stress at the key points in an engineering experiment. The results show that the effective notch stress method can be applied to the fatigue evaluation of orthotropic bridge deck, and it is superior to the hot spot stress method. In this paper, the effective notch stress of two different transversal plate transition forms is compared, and a more reasonable scheme is obtained, and the effective notch stress at the arc notch of U-rib transverse diaphragm is significantly larger than that at the welding root, which proves that the crack initiation is easier in the weld toe. Compared with the different thickness of U rib, it is found that the increase of thickness of U rib will lead to the decrease of fatigue strength at the weld seam of arc notch of U rib transverse partition plate. (5) the stress time history curve of a bridge is measured on the spot, and the rain flow counting method is used. The Miner criterion and the AASHTO code are used to calculate the equivalent stress amplitude of the weld seam where the orthotropic steel bridge face is prone to crack, and the estimated fatigue life is given. The results show that the fatigue life of the arc notch weld near the U-rib and the transverse partition does not meet the requirements of the specification. The reason of fatigue cracking is that the weld seam is not polished and the quality of weld is reduced.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441.4

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