细观尺度下正交异性钢桥面板-铺装层耦合疲劳损伤过程研究

The fatigue of the orthotropic steel deck (OSD) appears to be a local damage problem. It will not affect the structural safety as OSD is redundant enough, but may lead to the fatigue failure of the pavement, which is quite disadvantageous to the performance and the life cycle cost of the bridge. The applicant has conducted fatigue tests and numerical simulations on the OSD, to reveal the fatigue behavior and establish the corresponding analytic method, whilst the effect of pavement is not involved. As the OSD and the pavement both provide considerable contribution to the stiffness of the bridge deck system, it is necessary to analyze the fatigue process with respect to the damage of both and the coupling effect. In this project, therefore, the OSD and the pavement will be considered as an integrated structural system. The fatigue test with variable amplitude cycles will be conducted to analyze the fatigue process and failure mode of the OSD-pavement system. The fatigue crack growth model of the OSD will be build based on fracture mechanics, and the fatigue damage model of the pavement will be developed with respect to the mesoscopic characteristics and the viscoelastic constitutive of the asphalt concrete. Consequently, the damage coupling effect between the OSD and the pavement will be investigated, and the analytical method of the fatigue process of the OSD-pavement system will be established. The research results will benefit the life cycle performance evaluation of the bridge, and lay the foundation for proposing an integrated design method of the OSD-pavement system.

正交异性钢桥面板的疲劳是局部损伤问题，虽不影响结构安全性，但可能导致铺装层疲劳破坏，对桥梁的使用性能及全寿命成本十分不利。申请人的前期研究中，已通过疲劳试验及数值模拟揭示了正交异性钢桥面板关键焊缝处的疲劳行为，但其中未涉及铺装层的作用及疲劳损伤。考虑到桥面系的刚度由铺装层和正交异性钢桥面板共同提供，二者的疲劳损伤及相互作用影响下的疲劳过程有待研究。本项目拟针对正交异性钢桥面板-铺装层体系，开展变幅疲劳荷载试验，分析其开裂过程及失效模式，构建基于断裂力学的正交异性钢桥面板关键焊缝的疲劳裂纹扩展模型，以及考虑沥青混凝土材料细观尺度特征及粘弹性本构的铺装层疲劳损伤模型，探索二者的损伤耦合效应及影响规律，形成系统的正交异性钢桥面板-铺装层疲劳过程分析方法。研究成果将为该体系的全寿命周期性能评价提供条件，为提出正交异性钢桥面板及铺装层的一体化设计方法奠定基础。

正交异性钢桥面板的疲劳问题频繁发生，尤其是萌生与顶板-U肋焊缝处穿透顶板方向的疲劳裂纹，可能引起铺装层疲劳损伤加剧并导致钢结构锈蚀等次生病害，严重危害桥梁的力学性能及全寿命周期性能。对此，本项目考虑疲劳损伤过程中的细观尺度特征，对正交异性钢桥面板-铺装层体系的耦合疲劳损伤过程开展研究，内容涉及：1）考虑铺装层的正交异性钢桥面板疲劳试验及细观尺度特征分析；2）正交异性钢桥面板-铺装层结构体系疲劳行为；3）考虑疲劳损伤耦合的体系失效过程。.首先，基于已有相关疲劳试验成果开展无铺装/带铺装的正交异性钢桥面板试件试验，并由试验结果分析细观尺度下疲劳裂纹萌生、扩展至引发结构失效过程中的疲劳行为及影响因素。结合实桥病害数据处理分析，提出了正交异性钢桥面板疲劳裂纹、铺装层纵缝与轮压位置的相关性，并开展正交异性钢桥面板-铺装层结构体系有限元分析，对既有裂纹条件下的铺装层寿命进行初步预测。最后，建立基于连续介质损伤力学的正交异性钢桥面板-铺装层结构体系损伤演化模型，对比铺装层疲劳损伤演化速率变化以及裂纹本身扩展速率变化，分析二者疲劳损伤耦合效应，提出结构体系的疲劳损伤发展直至失效的典型过程。.项目研究成果有利于提高对正交异性钢桥面板与铺装层协同作用的结构体系疲劳行为机理的认识，推动其疲劳失效准则的细化及全寿命周期设计方法的提出。同时，部分成果有助于开展考虑既有疲劳裂纹条件下，基于上部结构改良的正交异性钢桥面板修复补强方法相关研究，促进其在实际工程中的应用。