腐蚀和徐变效应下钢管砼肋拱结构性能退化与时变可靠性研究

During the last twenty years, concrete filled steel tubular (CFST) arch bridge were widely used in the fields of road and rail transportations. However, during the period of service, the CFST arch bridges encounter with some problems such as the outer steel tube corrosion and the core concrete creep under long-term load, which impacts on their in-service performance, and even public safety. Moreover, the corrosion and the creep are time-variant stochastic processes. Therefore, it is of great significance in academic value and engineering application to investigate the time-variant reliability of corroded CFST arch bridges considering stochastic process-based models for corrosion and creep. .In present application program, CFST single arch rib under the combined effects of corrosion with long-term load will be used as the research object. Theoretical analysis, finite element numerical simulation and experimental research will be employed to examine the evolution mechanisms of corrosion damage on the surface of the outer steel tube and creep damage of the core concrete. First, the Gamma stochastic process-based probabilistic models for corrosion defect growth and creep growth will be established and the impacting mechanism of corrosion and creep effects on the resistance of the CFST members and arch rib will be interpreted. After that, a performance deterioration and reliability assessment and prediction method for CFST arch rib structures will be proposed based on the finite element model updating based on Bayes inference. Finally, an application example of this method will be given incorporating test simulation data of outdoor model scaled down real CFST arch bridge.

近20多年来，钢管混凝土拱桥在我国的公路和铁路交通运输中得到迅猛发展。它们在服役期间面临着钢管锈蚀和长期荷载作用下核心混凝土徐变问题，这些问题影响到钢管混凝土拱桥结构性能，甚至公共安全。另外，腐蚀和徐变均呈现随机特性。因此，开展腐蚀和徐变效应下钢管混凝土拱桥结构性能退化与可靠性的研究，具有重要的学术理论意义和工程应用价值。.本申请项目以腐蚀和徐变效应下钢管混凝土单圆管肋拱为研究对象，采用理论分析、有限元模拟和试验研究相结合的方法，分析钢管表面腐蚀损伤演化机理和核心混凝土徐变损伤演化机理，建立基于Gamma随机过程的腐蚀深度增长和徐变变形增长概率模型，阐释腐蚀和徐变效应对钢管混凝土构件、肋拱结构性能退化的影响机制，提出一种基于贝叶斯有限元模型更新理论的钢管混凝土肋拱结构性能退化和可靠性评估与预测方法。最后，融合室外缩尺模型实测数据，给出该方法的一个钢管混凝土单圆管肋拱应用范例。

本项目以宏观、微观材料科学、数学和力学理论为研究基础，运用应用数学和现代力学相结合的新思维以及现代测试及有限元数值模拟技术，对钢管混凝土拱桥结构的性能退化、评估、预测和控制开展基础研究。研究过程中主要有以下成果：（1）发明了一种基于马尔可夫链蒙特卡洛的Bayesian动态预测方法，该方法可以实现随机参数的更新，有效地预测结构性能退化轨迹和时变可靠性的变化规律；（2）研制了一系列研究钢管混凝土构件徐变性能的自平衡恒定加载装置，申请及授权多个相应的实验装置；（3）建立了时变锈蚀质量增长随机过程模型中随机参数的更新方法，实现动态预测钢材锈蚀质量增长轨迹；（4）开展一系列试验研究了模拟酸雨腐蚀环境下钢管混凝土构件静力性能的退化规律，提出了局部锈蚀钢管/钢管混凝土柱承载力实用计算公式；（5）建立了以局部锈蚀为主要影响因素的随机时变结构抗力的随机过程模型，提出了考虑局部锈蚀影响的钢管/钢管混凝土柱轴压试件抗力的概率预测方法；（6）阐释了腐蚀和徐变效应对结构性能退化的影响机制，揭示了结构性能退化规律；（7）采用有限元软件二次开发用户自定义材料子程序，根据粘弹性理论和徐变叠加原理，推出了考虑徐变损伤的三向应力作用的钢管混凝土轴压短柱率型徐变计算模型；（8）建立了考虑服役过程中的长期荷载和环境腐蚀的先后作用的钢管混凝土构件受力全过程有限元分析模型；（9）建立了基于随机过程的钢管表面腐蚀深度时变概率模型和核心混凝土徐变变形时变概率模型，构建了钢管混凝土拱桥服役时变可靠性评估与预测理论。本项目已公开发表论文 27 篇，其中期刊论文 22 篇，会议论文 5 篇，SCI收录 4 篇、EI 收录 10 篇、其余均为核心及核心以上期刊；授权发明专利 1 项、授权实用新型专利 2 项；登记软件著作权 3 项；荣获江西省科技进步奖一等奖 1 项。