腐蚀环境下节段式钢箱梁的疲劳性能研究

发布时间：2018-05-29 10:45

本文选题：钢箱梁 + 焊接细节　；参考：《南京航空航天大学》2015年硕士论文

【摘要】：钢结构在实际工程中应用广泛,但在大跨度钢桥的运营过程中也会产生各种病害,最典型的病害为钢箱梁腐蚀和出现疲劳裂纹。腐蚀和疲劳是钢箱梁退化的最常见的因素,而且这两种因素之间存在着相互促进作用。目前,对钢箱梁腐蚀疲劳性能的研究相对较少,因此本文设计了典型的节段式钢箱梁试件,在一定的荷载水平和加载频率下,研究了试件分别在未腐蚀、不同浓度腐蚀液作用下的疲劳性能,最后,通过建立体壳组合单元模式的分析模型对试件进行了热点应力分析。本文主要研究内容为:(1)通过腐蚀疲劳试验,对节段式钢箱梁试件的裂纹发展和寿命进行了研究,研究表明,四个试件发生疲劳破坏的位置均为节段式钢箱梁顶板与U肋焊缝处,且均在顶板母材上断裂;腐蚀对试件的疲劳性能有一定影响,经过3%Na Cl腐蚀液腐蚀的试件疲劳性能退化最为严重,其次为经过1%Na Cl腐蚀液腐蚀的试件和5%Na Cl腐蚀液腐蚀的试件,最后是未经过腐蚀的试件;(2)基于实测试件的疲劳残余应变,本文建立了三阶段的疲劳累积损伤公式,所提出的研究方法可供疲劳损伤分析参考;(3)钢箱梁腐蚀疲劳有限元建模计算,分别建立节段式钢箱梁试件的体单元模型和体壳组合单元模型进行计算,计算结果与试验结果进行验证,得到较为合理的有限元计算模型为体壳组合单元模型;(4)钢箱梁腐蚀疲劳的热点应力计算,采用体壳组合单元建模分析,由不同方法外推得到的焊缝焊趾处的热点应力不同;考虑腐蚀对节段式钢箱梁试件焊缝热点应力的影响,在试验荷载等级25k N、不考虑涂层对钢材的保护作用下,经过10年腐蚀的试件就不能满足工程的承载能力要求。
[Abstract]:Steel structures are widely used in practical projects, but in the operation of long-span steel bridges, there are also various diseases, the most typical of which are corrosion of steel box girders and fatigue cracks. Corrosion and fatigue are the most common factors in the degradation of steel box girders. At present, there are few researches on the corrosion fatigue performance of steel box girder, so the typical segmental steel box girder specimens are designed in this paper. At a certain load level and loading frequency, the specimens are studied respectively without corrosion. The fatigue properties of the specimens under the action of corrosion solution with different concentrations are analyzed. Finally, the hot spot stress analysis of the specimen is carried out by building the model of the three-dimensional shell combination element model. The main content of this paper is: (1) through corrosion fatigue test, the crack development and life of the steel box girder specimens are studied. The results show that the fatigue failure of the four specimens is located at the weld between the roof and U rib of the steel box girder. The fatigue properties of the specimens were affected by corrosion, and the fatigue properties of the specimens corroded by 3%Na Cl solution were the most serious, followed by those corroded by 1%Na Cl corrosion solution and 5%Na Cl corrosion solution, and the fatigue properties of the specimens were affected by the corrosion of the base metal on the roof, and the fatigue properties of the specimens corroded by the 3%Na Cl corrosion solution were the most serious. Finally, a three-stage fatigue cumulative damage formula is established based on the measured fatigue residual strain of the uncorroded specimen. The research method presented in this paper can be used as a reference for fatigue damage analysis and can be used to model and calculate the corrosion fatigue of steel box girder by finite element method, and the body element model and the combined body shell element model of the steel box girder specimen are established respectively. The calculated results are verified by the experimental results. The more reasonable finite element model is the hot stress calculation of the steel box girder corrosion fatigue, and the model is modeled by the body shell composite element. The hot spot stress at weld toe derived from different methods is different, considering the effect of corrosion on weld hot spot stress of steel box girder specimen, under the test load grade of 25kN, the protective effect of coating on steel is not considered. After 10 years of corrosion, the specimens can not meet the engineering load capacity requirements.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441.4

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