桥梁吊索高强钢丝疲劳裂纹扩展试验与数值模拟
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摘要
反复车辆荷载作用下,斜拉桥斜拉索及拱桥吊杆疲劳损伤问题日益严重。针对大跨桥梁中常用的镀锌高强钢丝,开展了应力比R分别为0.1、0.2、0.3的疲劳裂纹扩展试验,研究了应力比及应力幅对钢丝疲劳裂纹扩展性能的影响,每种应力比下的应力幅分别为140.4、152.1、163.8、175.5MPa。采用分步加载方法,设计不同加载应力幅在试件断裂面留下裂纹扩展时的条纹特征,利用光学显微镜对疲劳断口的疲劳条纹进行观测,得到了不同应力比下裂纹扩展深度与疲劳循环次数的a—N曲线,拟合了高强钢丝的疲劳裂纹扩展速率模型。试验结果表明:钢丝疲劳裂纹呈三阶段扩展,随着应力比R的增大,Paris公式中参数C变小,m变大。运用有限元软件ABAQUS模拟了裂纹扩展过程,定量分析了裂纹扩展径向与表面方向的关系,试验结果与有限元结果吻合较好。试验得到的疲劳裂纹扩展速率曲线,可用于大跨桥梁吊索的抗疲劳、防断裂设计及疲劳寿命评估。
The fatigue damage for cable-stayed bridge cable and arch bridge hanger become serious under cyclic loadings.The fatigue crack growth tests for galvanized high strength steel wires that are widely used in large-span bridges were performed with stress ratios of R=0.1,0.2 and 0.3.The effects of stress ratio and stress amplitude on the fatigue crack propagation of steel wires were studied,and four stress amplitudes were considered,i.e.140.4 MPa,152.1 MPa,163.8 MPa and 175.5 MPa.A two-step loading method was selected in the tests.Fatigue stripes were presented in the fracture surface using different loading amplitudes,and the stripes of the fatigue fracture were observed by an optical microscope.The a-Ncurves related to the crack propagation depth and the fatigue cycles under different stress ratios were obtained.The curves of fatigue crack propagation rate of the steel wires under different stress ratios were also fitted.The experimental results show that fatigue crack propagation exhibited three stages.As stress ratio increases,the parameters C in Paris formula decreases and the parameter m increases.The crack propagation process was simulated by the finite element software ABAQUS,and the relationship between the radial direction and the surface direction of crack growth is quantitatively analyzed.The experimental results are in good agreement with the finite element simulation results.The obtained curves of fatigue growth rate can be used for fatigue design,fracture control and fatigue life assessment for existing large-span bridge suspender.
The fatigue damage for cable-stayed bridge cable and arch bridge hanger become serious under cyclic loadings.The fatigue crack growth tests for galvanized high strength steel wires that are widely used in large-span bridges were performed with stress ratios of R=0.1,0.2 and 0.3.The effects of stress ratio and stress amplitude on the fatigue crack propagation of steel wires were studied,and four stress amplitudes were considered,i.e.140.4 MPa,152.1 MPa,163.8 MPa and 175.5 MPa.A two-step loading method was selected in the tests.Fatigue stripes were presented in the fracture surface using different loading amplitudes,and the stripes of the fatigue fracture were observed by an optical microscope.The a-Ncurves related to the crack propagation depth and the fatigue cycles under different stress ratios were obtained.The curves of fatigue crack propagation rate of the steel wires under different stress ratios were also fitted.The experimental results show that fatigue crack propagation exhibited three stages.As stress ratio increases,the parameters C in Paris formula decreases and the parameter m increases.The crack propagation process was simulated by the finite element software ABAQUS,and the relationship between the radial direction and the surface direction of crack growth is quantitatively analyzed.The experimental results are in good agreement with the finite element simulation results.The obtained curves of fatigue growth rate can be used for fatigue design,fracture control and fatigue life assessment for existing large-span bridge suspender.
引文
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[15]金属材料疲劳裂纹扩展速率试验方法:GB/T 6398-2000[S].北京:中国标准出版社.Standard test method for fatigue crack growth rates of metallic materials:GB/T 6398-2000[S].Beijing:Standards Press of China.(in Chinese)
[16]徐俊,陈惟珍,周健鸿,等.一种冷拔高强钢丝裂纹扩展速率的简易检测方法[P].中国专利:CN103868808A,2014-06-18.Xu J,Chen W Zh,Zhou J H,et al.A simple detection method for crack propagation rate of cold drawn high strength steel wire[P].Chinese patent:CN103868808A,2014-06-18.(in Chinese)
[17]Mahmoud K M.Fracture strength for a high strength steel bridge cable wire with a surface crack[J].Theoretical&Applied Fracture Mechanics,2007,48(2):152-160.
[2]Li F,Qu Y,Wang J.Bond life degradation of steel strand and concrete under combined corrosion and fatigue[J].Engineering Failure Analysis,2017,80:186-196.
[3]高欣.在役钢管混凝土拱桥吊杆损伤与系统可靠性分析方法[D].哈尔滨:哈尔滨工业大学,2011.Gao X.Analysis methods for suspender damage and system reliability of existing concrete filled steel tubular arch bridge[D].Harbin:Harbin Institute of Technology,2011.(in Chinese)
[4]Bartion S C,Vermaas G W,Duby P F,et al.Accelerated corrosion and embrittlement of high-strength bridge wire[J].Journal of Materials in Civic Engineering,2000,12(1):33-38.
[5]潘骁宇,谢旭,李晓章,等.腐蚀高强度钢丝的力学性能与评级方法[J].浙江大学学报,2014,48(11):1 917-1 924.Pan X Y,Xie X,Li X Zh,et al.Mechanical properties and grading method of corroded high-tensile steel wires[J].Journal of Zhejiang University,2014,48(11):1 917-1 924.(in Chinese)
[6]Mahmoud K M.Fracture behavior and strength assessment of bridge cable wire[C]∥First International Conference on Fatigue and Fracture in the Infrastructure:Bridges and Structures of the 21st Century,U-nited States:Philadelphia Pennsylvania,2006.
[7]Gjerding-Smith K,Johnsen R,Lange H I,et al.Wire fractures in locked coil cables[J].Bridge Structures,2006,2(2):63-77.
[8]曾勇,陈艾荣,马如进.带裂纹的悬索桥主缆钢丝的断裂强度分析[J].同济大学学报,2009,37(8):1 010-1 013.Zeng Y,Chen A R,Ma R J.Fracture strength of wires with cracks in suspension bridge[J].Journal of Tongji University,2009,37(8):1 010-1 013.(in Chinese)
[9]Nakamura S,Suzumura K,Tarui T.Mechanical properties and remaining strength of corroded bridge wires[J].Structural Engineering International,2004,14(1):50-54.
[10]Nakamura S,Suzumura K.Experimental study on fatigue strength of corroded bridge wires[J].Journal of Bridge Engineering,2013,18(3):200-209.
[11]李晓章,谢旭,潘骁宇,等.拱桥吊杆锈蚀高强钢丝疲劳性能试验研究[J].土木工程学报,2015,48(11):68-76.Li X Zh,Xie X,Pan X Y,et al.Experimental study on fatigue performance of corroded high tensile steel wires of arch bridge hangers[J].China Civil Engineering Journal,2015,48(11):68-76.(in Chinese)
[12]乔燕,李爱群,缪长青,等.腐蚀吊索钢丝力学性能退化研究[J].中外公路,2016,36(3):134-138.Qiao Y,Li A Q,Miu Ch Q,et al.Research on mechanical property degradation of corrosion sling steel wire[J].Journal of China&Foreign Highway,2016,36(3):134-138.(in Chinese)
[13]Sih G C,Tang X S,Mahmoud K M,et al.Effect of crack shape and size on estimating the fracture strength and crack growth fatigue life of bridge cable steel wires[J].Bridge Structures Assessment,2008,4(1):3-13.
[14]Sih G C,Tang X S,Li Z X,et al.Fatigue crack growth behavior of cables and steel wires for the cablestayed portion of Runyang bridge:Disproportionate loosening and/or tightening of cables[J].Theoretical&Applied Fracture Mechanics,2008,49(1):1-25.
[15]金属材料疲劳裂纹扩展速率试验方法:GB/T 6398-2000[S].北京:中国标准出版社.Standard test method for fatigue crack growth rates of metallic materials:GB/T 6398-2000[S].Beijing:Standards Press of China.(in Chinese)
[16]徐俊,陈惟珍,周健鸿,等.一种冷拔高强钢丝裂纹扩展速率的简易检测方法[P].中国专利:CN103868808A,2014-06-18.Xu J,Chen W Zh,Zhou J H,et al.A simple detection method for crack propagation rate of cold drawn high strength steel wire[P].Chinese patent:CN103868808A,2014-06-18.(in Chinese)
[17]Mahmoud K M.Fracture strength for a high strength steel bridge cable wire with a surface crack[J].Theoretical&Applied Fracture Mechanics,2007,48(2):152-160.