钢桥面板与纵肋焊接细节装配式快速加固协同受力体系的疲劳损伤演化机理

The fatigue cracks in deck-to-rib welded joint, whose reinforcement is difficult, has a serious harm to service performance of orthotropic steel bridge deck. while the traditional reinforcement method is expensive and the traffic is disrupted. A rapid reinforcement approach is proposed by introducing a assembly synergistic structure system consisting of original structure and assembled steel components. It has considerable advantages, such as convenient construction and little influence on traffic. The applicable reinforcement system and its fatigue performance are the basic research topics to ensure sustainable development of bridge engineering. Based on the coupling relationship between mechanical performance of synergistic system and its fatigue damage accumulation, the assembly synergistic structure system and its fatigue failure mechanism are to be investigated. The main research contents include: (1) Assembled reinforcement system: the index for the performance evaluation of the reinforcement system will be proposed, the key influencing factors of fatigue performance will be identified, and a rational structural form of reinforcement system will be developed. (2) Fatigue failure mechanism: the fatigue failure mode of reinforcement system will be determined. The fatigue crack propagation mechanism will be expounded by the exploring the coupling relationship between synergistic mechanical performance and fatigue damage accumulation, and the mechanism of fatigue damage evolution in reinforcement structure system would be revealed. (3) Evaluation method of remaining fatigue life: a quantitative method to verify fatigue damage effects caused by synergetic mechanical performance deterioration of reinforcement system will be proposed. The remaining fatigue life evaluation method of reinforcement system will be established considering deterioration of the synergetic mechanical performance. The investigation results in this study will provide a scientific basis for the design theory of whole service life of bridges. And they are also of great importance to the sustainable development of bridge engineering.

钢桥面板与纵肋焊接细节的疲劳开裂危害严重、加固困难，传统加固方法造价高昂且需中断交通。采用装配式方法将钢构件与既有结构形成协同受力体系的快速加固新方法施工便捷，对交通干扰小，具有突出优点。本项目以疲劳损伤与协同受力性能的耦合关系为切入点，对于装配式快速加固体系及其疲劳破坏机理进行深入研究。主要研究内容包括：（1）装配式加固体系：提出加固体系的疲劳性能强化指标，明确其关键影响因素并发展加固体系的合理结构形式；（2）疲劳破坏机理：确定加固体系的主导疲劳破坏模式，通过协同受力性能劣化与疲劳损伤累积的耦合关系阐明疲劳裂纹的扩展特性，揭示加固体系的疲劳损伤演化机理；（3）剩余疲劳寿命评估方法：提出协同受力性能劣化对于加固体系疲劳损伤效应的量化方法，建立基于协同受力性能劣化的加固体系剩余疲劳寿命评估方法。研究成果可为钢桥的全寿命周期设计理论提供科学依据，对促进桥梁工程的可持续发展具有重要意义。

钢桥面板与纵肋焊接细节的疲劳开裂危害严重、加固困难，传统加固方法造价高昂且需中断交通。采用装配式方法将钢构件与既有结构形成协同受力体系的快速加固新方法施工便捷，对交通干扰小，具有突出优点。本项目以疲劳损伤与协同受力性能的耦合关系为切入点，对于装配式快速加固体系及其疲劳破坏机理进行理论分析和试验研究工作，取得了一系列研究成果，主要包括：1.建立了钢桥面板与纵肋焊接细节疲劳裂纹扩展三维模拟方法，阐明了钢桥面板与纵肋焊接细节的疲劳裂纹扩展与性能劣化机理；2.基于钢桥面板与纵肋焊接细节疲劳裂纹的扩展特性，提出采用装配式加固、内焊加固的加固方法，采用线弹性断裂力学研究各加固方法对不同开裂模式下疲劳裂纹的加固效果；3.联合断裂力学和等效结构应力法阐明了加固前各开裂模式的疲劳累积损伤过程并建立基于加固体系主导开裂模式的疲劳性能评估方法；4.提出了纵肋与横隔板交叉构造细节装配式加固方法，通过模型试验研究其对疲劳裂纹的抑制效果；并采用加固后裂纹局部区域应力及断裂力学指标评估加固效果；5.提出了基于形状记忆合金钢桥面板纵肋对接焊缝的加固方法；开展了止裂孔加固效果的试验研究，并阐明了止裂孔对钢桥面板疲劳开裂加固效果的影响机理；6.阐明了焊接残余应力与初始制造缺陷两类关键影响因素对典型焊接构造细节疲劳抗力的劣化效应机制；7.基于结构应力建立钢桥面板结构疲劳抗力的统一评估方法，并提出了基于主导疲劳失效模式的正交异性钢桥面板结构体系疲劳抗力评估，明确了其主导疲劳失效模式和结构体系的实际疲劳抗力；8.构建了疲劳损伤评估和指标可视化的正交异性钢桥面板疲劳损伤的智能监测与评估系统。相关研究成果具有广阔的应用前景，已在包括常泰大桥在内的多项重大工程建设项目中得到了成功应用；9.基于概率统计理论和可靠度理论统一于以断裂力学为基础的疲劳评估框架，提出了基于概率断裂力学的疲劳可靠度评估方法。