正交异性钢桥面板肋-面板焊缝疲劳分析
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摘要
基于焊缝的局部三维断裂力学模型和超重多轴货车的载荷谱,进行正交异性钢桥面板的肋-面板焊缝表面裂纹的疲劳寿命分析。采用Schwartz-Neuman交替法计算肋-面板焊缝处半椭圆表面裂纹的应力强度因子,基于裂尖反向塑性区模型考虑循环载荷中压应力对疲劳裂纹扩展的作用。正交异性钢桥面板的肋-面板焊缝的应力计算结果表明:超载货车作用下肋-面板焊缝处的横向应力峰值和应力幅都有明显增加;相比于标准疲劳荷载车,超载货车作用下肋-面板焊缝处半椭圆表面裂纹的裂纹扩展率增大了6.1倍;对应于正交异性钢桥面板的肋-面板焊缝处的拉-压循环应力,平面应变状态下的裂尖反向塑性区使裂纹扩展率增加了3.7倍;基于所得裂纹扩展速率,本研究给出仅在严重超载的五轴和六轴货车作用下正交异性钢桥面板的肋-面板焊缝疲劳寿命不足20年,远远低于桥梁的设计寿命。因此,考虑超载多轴货车的载荷谱和循环载荷中的压应力对肋-面板焊缝疲劳裂纹扩展的影响十分重要。
The fatigue life of surface crack at the rib-to-deck welded joints of orthotropic steel deck is analyzed by using the local three-dimensional(3 D) fracture mechanics model of welded joints and the load spectrum of overloaded multi-axle trucks. The stress intensity factors of semi-ellipse surface cracks at the welded joints are computed using the Schwartz-Neuman alternating method, and the effects of compressive stress in the cyclic stress with negative stress ratio on fatigue crack growth are taken into account by the reverse plastic zone model of crack tip. The results show that both the peak transverse stress and the stress amplitude at the rib-to-deck welded joints increase significantly under the action of overloaded trucks. Compared with the action of normal trucks, the crack growth rate of the semi-ellipse surface cracks at the rib-to-deck welded joints under the action of overloaded trucks increases by 6.1 times. Corresponding to the cyclic stress with negative stress ratio at the rib-to-deck joints, the reverse plastic zone of crack tips under plane strain condition increases the crack growth rate by 3.7 times. Based on the obtained crack growth rate, this study shows that fatigue life of the rib-to-deck welded joints is less than 20 years merely under the heavily overloaded five-axle and six-axle trucks, which is far less than the design life of the bridge. Therefore, it is very important to account for the effects of load spectrum of overloaded multi-axle trucks and compressive stress in the cyclic stress on fatigue crack growth at the rib-to-deck welded joints.
The fatigue life of surface crack at the rib-to-deck welded joints of orthotropic steel deck is analyzed by using the local three-dimensional(3 D) fracture mechanics model of welded joints and the load spectrum of overloaded multi-axle trucks. The stress intensity factors of semi-ellipse surface cracks at the welded joints are computed using the Schwartz-Neuman alternating method, and the effects of compressive stress in the cyclic stress with negative stress ratio on fatigue crack growth are taken into account by the reverse plastic zone model of crack tip. The results show that both the peak transverse stress and the stress amplitude at the rib-to-deck welded joints increase significantly under the action of overloaded trucks. Compared with the action of normal trucks, the crack growth rate of the semi-ellipse surface cracks at the rib-to-deck welded joints under the action of overloaded trucks increases by 6.1 times. Corresponding to the cyclic stress with negative stress ratio at the rib-to-deck joints, the reverse plastic zone of crack tips under plane strain condition increases the crack growth rate by 3.7 times. Based on the obtained crack growth rate, this study shows that fatigue life of the rib-to-deck welded joints is less than 20 years merely under the heavily overloaded five-axle and six-axle trucks, which is far less than the design life of the bridge. Therefore, it is very important to account for the effects of load spectrum of overloaded multi-axle trucks and compressive stress in the cyclic stress on fatigue crack growth at the rib-to-deck welded joints.
引文
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[13]American Association of State Highway and Transportation Officials.LRFD bridge design specifications:AASHTO-2005[S].Washington D.C:American Association of State Highway and Transportation Officials,2005.
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[15]杜青,石广玉.拉压循环载荷下正交异性钢桥面板肋-面板焊缝裂纹扩展分析[J].计算力学学报,2017,34(6):698-703.(DU Qing,SHI Guangyu.Crack growth analysis of the rib-to-deck welded joints of orthotropic steel deck under cyclic loading with negative stress ratio[J].Chinese journal of computational mechanics,2017,34(6):698-703(in Chinese)).
[16]HAN Z D,ATLURI S N.SGBEM(for cracked local subdomain)-FEM(for uncracked global structure)alternating method for analyzing 3D surface cracks and their fatigue-growth[J].Computer modeling in engineering and sciences,2002,3(6):699-716.
[17]赵欣欣.正交异性钢桥面板疲劳设计参数和构造细节研究[D].北京:中国铁道科学研究院,2011.(ZHAO Xinxin.Research on fatigue design parameter and structural details for orthotropic deck[D].Beijing:China Academy of Railway Sciences,2011(in Chinese)).
[2]KISS K,DUNAI L.Fracture mechanics based fatigue analysis of steel bridge decks by two-level cracked models[J].Computers&structures,2002,80(27/28/29/30):2321-2331.
[3]唐亮,黄李骥,刘高,等.正交异性钢桥面板顶板贯穿型疲劳裂纹研究[J].公路交通科技,2012,29(2):59-66.(TANG Liang,HUANG Liji,LIU Gao,et al.Research on fatigue cracks through deck-plate in orthotropic steel deck[J].Journal of highway and transportation research and development,2012,29(2):59-66(in Chinese)).
[4]张允士,李法雄,熊锋,等.正交异性钢桥面板疲劳裂纹成因分析及控制[J].公路交通科技,2013,30(8):75-80.(ZHANG Yunshi,LI Faxiong,XIONG Feng,et al.Cause analysis and control of measures fatigue cracks in orthotropic steel deck[J].Journal of highway and transportation research and development,2013,30(8):75-80(in Chinese)).
[5]何东升,肖海珠,张晓勇.公路正交异性钢桥面板细节疲劳研究[J].公路交通科技,2016,33(1):76-81.(HE Dongsheng,XIAO Haizhu,ZHANG Xiaoyong.Research on detail fatigue of orthotropic steel deck in highway bridge[J].Journal of highway and transportation research and development,2016,33(1):76-81(in Chinese)).
[6]XIAO Z G,YAMADA K,YA S,et al.Stress analyses and fatigue evaluation of rib-to-deck joints in steel orthotropic decks[J].International journal of fatigue,2008,30(8):1387-1397.
[7]刘扬,张海萍,邓扬,等.公路桥梁车辆荷载建模方法及疲劳寿命评估[J].应用力学学报,2016,33(4):652-659.(LIU Yang,ZHANG Haiping,DENG Yang,et al.Research on probabilistic model of highway vehicle loads and fatigue life assessment of highway bridges[J].Chinese journal of applied mechanics,2016,33(4):652-659(in Chinese)).
[8]张高楠,石广玉,王晓丹.正交异性钢桥肋-桥面板焊缝裂纹的三维断裂力学分析[J].计算机辅助工程,2014,23(6):70-74.(ZHANGGaonan,SHI Guangyu,WANG Xiaodan.3D fracture mechanics analysis on cracks at rib-deck weld joints of orthotropic steel bridge[J].Computer aided engineering,2014,23(6):70-74(in Chinese)).
[9]SHI G Y,LI X X,ZHANG G N.Evaluation of stress intensity factor range in the prediction of fatigue crack growth at rib-to-deck welded joints of orthotropic steel decks[J].Advanced materials research,2013,671/672/673:969-973.
[10]SILVA F S.Crack closure inadequacy at negative stress ratios[J].International journal of fatigue,2004,26(3):241-252.
[11]沙宇,张嘉振,白士刚,等.拉-压循环加载下铝合金疲劳裂纹扩展的压载荷效应研究[J].工程力学,2012,29(10):327-334.(SHAYu,ZHANG Jiazhen,BAI Shigang,et al.Study on the effect of compression loading on fatigue crack growth of aluminium under tension-compression cycle[J].Engineering mechanics,2012,29(10):327-334(in Chinese)).
[12]CHEN W Z,XU J,YAN B C,et al.Fatigue load model for highway bridges in heavily loaded areas of China[J].Advanced steel construction,2015,11(3):322-333.
[13]American Association of State Highway and Transportation Officials.LRFD bridge design specifications:AASHTO-2005[S].Washington D.C:American Association of State Highway and Transportation Officials,2005.
[14]宗亮,施刚,王元清,等.Q345q D桥梁钢对接焊缝疲劳裂纹扩展性能试验研究[J].铁道科学与工程学报,2015,36(3):37-44.(ZONGLiang,SHI Gang,WANG Yuanqing,et al.Experimental study on fatigue crack growth rate of Q345qD bridge steel[J].Journal of railway science and engineering,2015,36(3):37-44(in Chinese)).
[15]杜青,石广玉.拉压循环载荷下正交异性钢桥面板肋-面板焊缝裂纹扩展分析[J].计算力学学报,2017,34(6):698-703.(DU Qing,SHI Guangyu.Crack growth analysis of the rib-to-deck welded joints of orthotropic steel deck under cyclic loading with negative stress ratio[J].Chinese journal of computational mechanics,2017,34(6):698-703(in Chinese)).
[16]HAN Z D,ATLURI S N.SGBEM(for cracked local subdomain)-FEM(for uncracked global structure)alternating method for analyzing 3D surface cracks and their fatigue-growth[J].Computer modeling in engineering and sciences,2002,3(6):699-716.
[17]赵欣欣.正交异性钢桥面板疲劳设计参数和构造细节研究[D].北京:中国铁道科学研究院,2011.(ZHAO Xinxin.Research on fatigue design parameter and structural details for orthotropic deck[D].Beijing:China Academy of Railway Sciences,2011(in Chinese)).