车辆荷载与环境因素共同作用下钢-混凝土组合梁桥疲劳性能研究

Suffered with combined effects of vehicle dynamic load and environment erosion, the fatigue failure of steel-concrete composite girder bridges have become increasingly striking. Forever, the impact of environment erosion on structural fatigue performance is not considered in China’s design and assessment theory system of steel-concrete composite girder bridges, and influence of combined effects of vehicle load and environment erosion on fatigue behavior is not considered too. Therefore, this project intends to carry out fatigue performance study of steel and concrete composite girder bridges under the combined action of vehicle load and environmental factors. First, the fatigue damage mechanism of steel-concrete composite girder bridges will be studied, and fatigue life prediction method based on equivalent initial flaw size will be proposed. Next, in view of research on fatigue damage mechanism of pre-corrosive composite structures, the calculation method of fatigue rigidity and midspan deflection will be set up, and fatigue life prediction model of pre-corrosive steel-concrete composite girders will be established. Finally, the combined action mechanism and fatigue damage evolution mechanism will be studied under vehicle load and environment combined effects, and the test simulation method considering of combined effects of fatigue load and environment erosion will be build. Furthermore, corrosion fatigue crack growth rate model and fatigue damage evolution equation will be developed, and fatigue life prediction model based on damage evolution will be build under vehicle load and environment combined effects.

钢-混凝土组合梁桥承受车辆动荷载和环境侵蚀的共同作用，疲劳失效问题日益突出。目前我国钢-混凝土组合梁桥设计与评估理论体系没有考虑环境因素影响，车辆荷载与环境因素的共同作用对组合梁桥疲劳性能影响同样没有考虑。为此，本项目拟开展车辆荷载与环境因素共同作用下钢-混凝土组合梁桥疲劳性能研究，内容包括：研究车辆荷载作用下钢-混凝土组合梁桥疲劳损伤机理，提出基于等效初始裂纹尺寸的钢-混凝土组合梁疲劳寿命预测方法；研究预腐蚀钢-混凝土组合梁的疲劳损伤机理，建立预腐蚀钢-混凝土组合梁疲劳刚度及跨中挠度计算方法，提出预腐蚀钢-混凝土组合梁疲劳寿命预测模型；研究车辆荷载与环境因素的共同作用机制和钢-混凝土组合梁桥疲劳损伤演化机理，提出车辆荷载与环境因素共同作用试验模拟方法，建立腐蚀疲劳裂纹扩展速率模型和疲劳损伤演化方程，提出车辆荷载与环境因素共同作用下基于损伤演化规律的钢-混凝土组合梁结构疲劳寿命预测模型。

钢-混凝土组合梁桥承受车辆动荷载和环境侵蚀的共同作用，疲劳失效问题日益突出。本项目通过理论研究、数值模拟和模型试验，对车辆荷载与环境因素共同作用下钢-混凝土组合梁桥的疲劳性能进行了研究。.首先，以栓钉连接件为主要研究对象，对人工气候环境加速锈蚀后的锈蚀栓钉连接件进行了静载破坏试验和疲劳破坏试验。在试验结果的基础上，建立了锈蚀栓钉连接件抗剪承载力退化模型，提出了基于内聚力模型（CZM）的锈蚀栓钉连接件静力性能数值模拟方法。基于锈蚀栓钉连接件的疲劳试验和数值模拟，提出了锈蚀栓钉连接件S-N疲劳寿命计算公式；在此基础上，建立了基于断裂力学的锈蚀栓钉连接件疲劳寿命计算模型。通过对锈蚀栓钉连接件疲劳试验结果分析，揭示了锈蚀栓钉连接件疲劳破坏机理和疲劳刚度退化过程。.其次，基于栓钉锈蚀钢-混凝土组合梁抗弯性能试验，建立了栓钉锈蚀钢-混凝土组合梁剩余抗弯承载力计算公式，提出了栓钉锈蚀钢-混凝土组合梁抗弯刚度退化模型。.最后，基于预腐蚀钢-混凝土组合梁静力性能和疲劳性能试验，揭示了栓钉锈蚀和钢梁表面坑锈蚀对钢-混凝土组合梁的静力及疲劳破坏模式的影响。通过对栓钉锈蚀结果的分析，揭示了氯盐环境下结合面侵蚀是引起栓钉锈蚀的主要途径。基于疲劳试验的结果分析，建立了钢梁锈蚀后钢-混凝土组合梁S-N疲劳寿命公式。.