在役钢筋混凝土拱桥劣化机理与衰变模式研究

Reinforced concrete (RC) arch bridges are widely used in China, especially in mountainous areas, because of their high structural stiffness, beautiful appearance and economy. However, the degradation of the structural performance affects the safety of arch bridges. Due to the coupling effect of the environment and load, the degradation mechanism of RC arch bridges is complex. The project is focused on the two key scientific issues. The one is the relevant characteristics between the material deterioration, the arch axis deformation and the resistance decay of RC arch bridges. The other is the intrinsic mechanism and extraction algorithm of the damage index evolution with the deterioration effect. It aims to clarify the deterioration mechanism of RC arch bridges and excavate the structural damage characteristic parameters by means of the theoretical analysis, model test and numerical simulation. Firstly, based on the stress characteristics and the material deterioration model of arch bridge, the internal relationship between multiple deterioration factors and structural damage were analyzed, and the decay mechanism was revealed. Then, based on the numerical simulation and the whole process failure test, the behavior evolution law and failure mode of the deteriorated arch were analyzed. Moreover, the resistance decay model of the arch bridge considering the dual deterioration effect of material and arch axis was established. Finally, the analytical mechanics model between material deterioration, arch axis deterioration and performance characteristics was established. And the damage state identification method of arch bridge based on physical model and data-driven hybrid model was proposed. The research of this project can provide theoretical and technical supports for the performance evaluation of RC arch bridges in service in China.

钢筋混凝土（RC）拱桥因结构刚度大、美观经济而在我国特别是山区应用广泛。但结构的性能退化影响拱桥安全，由于环境与荷载作用的耦合影响，RC拱桥承载特性的劣化机理复杂。项目抓住RC拱桥材料劣化--拱轴变形--抗力衰变之间的关联特性、损伤指标随劣化效应演化的內禀机制与提取算法两个关键科学问题，采用理论分析、模型试验、数值模拟相结合的研究手段，以明晰RC拱桥劣化机理、挖掘结构损伤特征参数为目标开展。首先，基于拱桥受力特征与材料劣化模型，解析多重劣化因素与结构损伤的内在关联，揭示RC拱衰变机理。其次，基于数值仿真和全过程破坏试验，剖析劣化拱的行为演化规律与失效模式，构建考虑材料、拱轴线双重劣化效应的拱桥抗力衰变模型。最后，建立材料劣化、拱轴线劣化与性能特征指标间的解析力学模型，提出基于物理模型与数据驱动混合模型的拱桥模式识别方法。本项目研究可为我国量大面广的服役RC拱桥性能评估提供理论和技术支撑。

钢筋混凝土（RC）拱桥因结构刚度大、美观经济而在我国特别是山区应用广泛。但结构的性能退化影响拱桥安全，由于环境与荷载作用的耦合影响，RC拱桥承载特性的劣化机理复杂。项目抓住RC拱桥材料劣化--拱轴变形--抗力衰变之间的关联特性、损伤指标随劣化效应演化的內禀机制与提取算法两个关键科学问题，采用理论分析、模型试验、数值模拟相结合的研究手段，以明晰RC拱桥劣化机理、挖掘结构损伤特征参数为目标开展，主要成果如下：.（1）解析了混凝土结构开裂、钢筋屈曲、粘结滑移、箍筋约束效应下降、界限高度降低等多重劣化因素对于结构抗力的影响机理，利用Hermite插值与Fourier级数生成的M-N曲线，构建了考虑实际纯弯点、界限点、纯压点获取的劣化RC构件抗力衰变模型。系统开展了不同锈蚀水平下RC轴压/偏压柱的静力性能试验，较为全面地研究了锈蚀钢筋形态、锈胀裂缝分布、荷载-位移曲线、荷载-应变关系、极限承载力、破坏形态及应变场等承载力演化信息。.（2）开展了荷载与环境耦合作用下的RC拱桥抗力演化模型试验，对比了不同锈胀损伤RC拱肋的荷载挠度关系，明晰了服役受力状态下劣化拱桥的裂缝发展与破坏形态，揭示了劣化RC拱的失效模式；在考虑材料劣化效应的基础上，解析了考虑材料劣化与拱轴线劣化双重劣化效应的锈损拱桥破坏机理，揭示了有损拱桥的恶性循环劣化路径，即锈胀导致刚度退化--拱结构变形增大--拱肋附加弯矩增大--结构损伤进一步恶化--锈胀损伤进一步发展，推导了考虑强度、刚度耦合退化作用的RC拱桥承载力预测公式。.（3）针对钢筋锈蚀导致的钢筋混凝土(RC)拱桥结构损伤问题，建立了钢筋锈蚀与结构刚度退化的映射关系，获取了锈蚀率与损伤特征指标之间的定量关系，提出了基于加速度数据时序分析的锈蚀RC拱桥损伤识别方法，构建了用于定位损伤位置和识别损伤程度的损伤敏感性特征指标，实现了多损伤定位及损伤程度的概率输出。