钢筋混凝土梁式桥全寿命损伤演化与车载极限承载能力评定方法

The vehicle load carrying capacity is the dominant control load and state of reinforced concrete (RC) beam bridges. For the past few years, beam bridge failures or collapses have occurred because of the vehicle over load, resulting significant economic loss, casualties, and very bad social impact. This research project will establish the material constitutive relation parameter degradation function of concrete, steel, prestress wire, and its bond surface, based on the study of durability damage, included steel corrosion, bond performance degradation, fatigue damage, and time dependent prestress loss, of basic components, included girder, pier, and rigid node, of the reinforced concrete simply support beam and rigid-frame continuous beam bridge. On this basis, nonlinear skeleton curve parameter degradation function of the basic bridge components will be deduced. Then, elaborate beam-column model of damaged components will be established based on the previous study, and fiber model will be used to calibrate and verify the beam-column model. Numeric substructure test method will be adopted to analyze the ultimate load carrying capacity evolutional law of the bridge life-cycle, with elaborate fiber model and the beam-column model. At last, the life-cycle performance evaluation system of beam bridge will be established, and application scheme for the practical engineering will be provided. This project is anticipated to provide some theory basis for normal and overload safety stock of bridge’s different service period. It will also provide some scientific basis to decide the maintenance strategy.

钢筋混凝土梁式桥的车载承载能力是主要的控制荷载和状态，我国近年来车辆超载失效或破坏时有发生，造成了重大的经济损失、人员伤亡和不良的社会影响。本项目通过研究钢筋混凝土简支梁和钢构连续梁桥基本构件（主要是桥面、桥墩和刚构节点）全寿命期耐久性损伤（包括钢筋锈蚀和粘结性能退化、疲劳损伤积累、及时间相关的预应力损失）演化规律，建立相应混凝土、钢筋、预应力钢绞线及其粘结界面材料本构关系参数退化模型和模型参数确定方法。在此基础上建立桥梁基本构件非线性全骨架曲线参数退化规律和计算模型及其模型参数确定方法；进而通过纤维模型、杆系模型的精细化建模及其相互验证，同时采用数值子结构方法，分析桥梁结构全寿命车载极限承载能力退化规律，建立钢筋混凝土梁式桥全寿命正常车载、超载和极限车载性能评估体系，并提供实际工程应用方案。通过本项目的研究，为桥梁结构不同服役期车辆正常承载、超载的安全储备评定或维修报废决策提供科学依据。

本项目重点研究了梁式桥基本构件全寿命器耐久性损伤演化规律，建立相应混凝土、钢筋、预应力钢绞线及其粘结界面材料本构关系参数退化模型和模型参数确定方法，进而分析桥梁结构全寿命车载极限承载能力退化规律。具体内容包括以下几个方面：.1）锈蚀钢筋混凝土粘结性能研究：本项目进行了系统的钢筋混凝土粘结性能试验，并通过对已有研究及本项目试验中拔出试件的粘结强度退化数据进行统计，得到了三段式粘结强度退化试验模型及保守模型；提出了简化的三段式粘结-滑移本构模型并从粘结应力释放率的角度考虑了锈蚀率对残余粘结强度影响。.2）锈蚀预应力钢筋混凝土梁疲劳性能研究：通过锈蚀预应力钢筋混凝土梁进行先重载后正常幅值加载的两级变幅疲劳试验，研究不同重载循环次数对正常幅值疲劳加载下试验梁性能退化及疲劳寿命的影响，对比经历重载后的锈蚀梁与未锈蚀梁疲劳性能的差异，并基于两级变幅加载下疲劳累积损伤理论，对重载后锈蚀梁及非锈蚀梁的疲劳寿命进行预测，为重载腐蚀损伤预应力混凝土梁的疲劳寿命评估提供参考。.3）锈蚀钢筋混凝土梁非线性全过程分析：通过有限元软件ANSYS对钢筋混凝土梁构件进行精细化和非线性全过程分析，深入研究锈蚀对既有RC梁的失效机理、失效模式、极限承载能力的影响，并总结既有锈蚀RC梁存在的五种失效模式及其极限承载能力的评估方法。.4）作为项目的扩展，通过高温下及高温后的拔出试验研究了锈蚀和高温耦合作用下，钢筋混凝土粘结滑移性能的退化模型；通过4点加载研究了高温下及高温后锈蚀T型预应力混凝土梁的承载能力的退化模型；通过锈蚀钢筋混凝土梁落锤试验，揭示钢筋锈蚀程度对混凝土梁抗冲击行为劣化过程的影响机理。