港珠澳大桥正交异性钢桥面板疲劳特性研究

Study on fatigue features of orthotropic decks in steel box girder of Hong Kong-Zhuhai-Macao Bridge

由结构体系和受力特性共同决定,疲劳问题是正交异性钢桥面板应用和发展所面临的重要课题。以典型的正交异性桥面板钢箱梁桥——港珠澳大桥为研究对象,通过足尺试件模型对5类重要的正交异性钢桥面板疲劳易损部位进行试验和理论研究。选取最易发生疲劳损伤的梁段作为模型设计的依据,针对各关键疲劳易损部位设计4组共8个足尺疲劳试件模型;对设计寿命期内各疲劳易损部位的疲劳特性进行试验验证,在此基础上选取典型疲劳易损部位进行疲劳损伤及疲劳性能试验,建立基于理论模型和弹塑性断裂力学的疲劳损伤裂纹扩展模拟方法。研究结果表明:港珠澳大桥正交异性钢桥面板的疲劳性能满足设计要求;正交异性钢桥面板疲劳易损部位的疲劳性能存在较大差异;疲劳裂纹附近区域的应力分布随裂纹的扩展而不断发生改变,可据此判别裂纹的萌生并监测其扩展;所提出的方法适用于待研究疲劳易损部位的疲劳寿命评估。

Fatigue is one of the most important issues for orthotropic steel bridge deck due to its structural complexity and complicated mechanical properties. Based on the steel box girder of Hong Kong-Zhuhai-Macao Bridge,five predominant types of details vulnerable to fatigue in orthotropic steel bridge deck were studied based on full-scale model tests and theoretical study. Furthermore,the structural mechanical properties were investigated by 3D nonlinear finite element method. The most fragile girder segment was determined,and test models were then designed. According to systematic comparison of design schemes,eight full-scale fatigue test specimens,which may be divided into four groups,were fabricated to test the fatigue properties of vulnerable details during design lifetime. Fatigue damage tests and theoretical study on fatigue resistances of typical fatigue details were carried out. The results indicate that the fatigue properties of orthotropic steel decks of Hong Kong-Zhuhai-Macao Bridge satisfy the design requirements,but the fatigue properties of critical details of orthotropic steel decks are quite different. Significant strain changes during the propagation of fatigue damage can be used to identify the initiation of fatigue cracks and monitor the propagation of cracks. Hence,the proposed theoretical model and method can be used for the evaluation of fatigue life of typical fatigue details.