制作误差对纵肋与横隔板焊接细节疲劳抗力的劣化效应
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摘要
纵肋与横隔板焊接细节是正交异性钢桥面板中的典型疲劳易损细节。受到制作焊接技术等因素的制约,该处构造细节的制作误差难以完全规避。为探究其对关注细节疲劳抗力的劣化效应,针对模型试验中产生的制作误差,基于线弹性断裂力学的扩展有限元方法(XFEM),建立含裂纹有限元模型。通过对构造细节的第一主应力场以及断裂力学计算结果的分析对比,得到制作误差对纵肋与横隔板焊接细节疲劳抗力的劣化效应。研究结果表明:试验模型中产生了横隔板犄角切割垂直度误差(Ⅰ区)与横隔板开孔切割断面凹陷误差(Ⅱ区),其中I区制作误差的产生难以改变疲劳裂纹开裂模式;Ⅱ区制作误差削弱了横隔板开孔犄角处的纵向刚度,减轻了横隔板对围焊下方的约束;Ⅱ区制作误差一旦产生,横隔板弧形开孔处Ⅰ—Ⅲ型应力强度因子幅值均会迅速增大,随着制作误差的增加,Ⅰ—Ⅲ型应力强度因子幅值増势减缓。相对于无制作误差工况,Ⅱ区初始制作误差工况关注细节疲劳寿命减少了21.4%,试验制作误差工况关注细节疲劳寿命减少了28.5%。
The welding details of the longitudinal ribs and the transverse plate are typical fatigue-prone details in the orthotropic steel deck plate. Due to factors such as manufacturing welding technique, manufacturing errors in the details of the structure cannot be completely avoided. In order to explore its deteriorating effect on details' fatigue resistance, the paper focused on manufacturing errors generated in the model test, and based on the extended finite element method of linear elastic fracture mechanics, a finite element model containing a crack block was established. Through the analysis and comparison of the first principal stress field and fracture mechanics calculation results of the structural details, the deteriorative effect of manufacturing errors on the fatigue resistance of the welding details of longitudinal ribs and diaphragms was obtained. The results showed that the cutting vertical degree error of the transverse diaphragm(zone I) and the error of the cutting section of the transverse diaphragm opening(zone II) were generated. in the test model. Among them, it was difficult to change the fatigue cracking mode caused by the manufacturing errors in the zone I; the cutting stiffness in the zone II weakened the longitudinal stiffness at the opening of the diaphragm, and reduced the constraints of the diaphragms on the underside of the welds; once the cutting error in zone II occurred, the magnitude of the I～III stress intensity factors in the arcuate openings of the diaphragms would increase rapidly. With the increase of manufacturing errors, the increase of I～III stress intensity factor slowed down. Compared with the no error condition, the initial manufacturing error condition in zone II reduced the fatigue life by 21.4%, and the test manufacturing error condition reduced the detail fatigue life by 28.5%.
The welding details of the longitudinal ribs and the transverse plate are typical fatigue-prone details in the orthotropic steel deck plate. Due to factors such as manufacturing welding technique, manufacturing errors in the details of the structure cannot be completely avoided. In order to explore its deteriorating effect on details' fatigue resistance, the paper focused on manufacturing errors generated in the model test, and based on the extended finite element method of linear elastic fracture mechanics, a finite element model containing a crack block was established. Through the analysis and comparison of the first principal stress field and fracture mechanics calculation results of the structural details, the deteriorative effect of manufacturing errors on the fatigue resistance of the welding details of longitudinal ribs and diaphragms was obtained. The results showed that the cutting vertical degree error of the transverse diaphragm(zone I) and the error of the cutting section of the transverse diaphragm opening(zone II) were generated. in the test model. Among them, it was difficult to change the fatigue cracking mode caused by the manufacturing errors in the zone I; the cutting stiffness in the zone II weakened the longitudinal stiffness at the opening of the diaphragm, and reduced the constraints of the diaphragms on the underside of the welds; once the cutting error in zone II occurred, the magnitude of the I～III stress intensity factors in the arcuate openings of the diaphragms would increase rapidly. With the increase of manufacturing errors, the increase of I～III stress intensity factor slowed down. Compared with the no error condition, the initial manufacturing error condition in zone II reduced the fatigue life by 21.4%, and the test manufacturing error condition reduced the detail fatigue life by 28.5%.
引文
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[3] WOLCHUK R. Lessons from Weld Cracks in Orthotropic Decks on Three European Bridges[J]. Journal of Structural Engineering, 1990, 116(1): 75-84.
[4] BELYTSCHKO T, BLACK T. Elastic Crack Growth in Finite Elements with Minimal Remeshing[J]. International Journal for Numerical Methods in Engineering, 1999, 45(5): 601-620.
[5] MO?S N, DOLBOW J, BELYTSCHKO T. A Finite Element Method for Crack Growth Without Remeshing[J]. International Journal for Numerical Methods in Engineering, 1999, 46: 131-150.
[6] 黄宏伟, 刘德军, 薛亚东, 等. 基于扩展有限元的隧道衬砌裂缝开裂数值分析[J]. 岩土工程学报, 2013, 35(2): 266-275.
[7] 王春生, 翟慕赛, 唐友明,等. 钢桥面板疲劳裂纹耦合扩展机理的数值断裂力学模拟[J]. 中国公路学报, 2017, 30(3): 82-95.
[8] 袁继胜. 钢结构桥梁加工安装技术的研究与应用[D]. 郑州: 郑州大学, 2010.
[9] 李沛霖. 钢结构切割与组装尺寸偏差的分析与研究[D]. 西安: 长安大学, 2011.
[10] 陈军. 超高层建筑钢结构加工与安装技术研究[D]. 杭州: 浙江理工大学, 2013.
[11] 穆秀玲, 马晖, 杨振军. 数控火焰切割面质量缺陷及原因分析[J]. 装备制造技术, 2013(7): 81-83.
[12] 王晓峰. 水平集方法及其在图像分割中的应用研究[D]. 合肥: 中国科学技术大学, 2009.
[13] 中华人民共和国交通运输部. 公路钢结构桥梁设计规范:JGT D64—2015[S]. 北京:人民交通出版社, 2015.