剪力连接件疲劳损伤导致的钢-混凝土组合梁桥刚度退化机理研究

The fatigue damage of shear connectors will lead to stiffness degradation of steel-concrete composite beam bridge, which influences the riding comfort, running safety and structure security. On the basis of summarizing existing research achievements, the stiffness degradation mechanism of steel-concrete composite beam bridge, which caused by shear connectors' fatigue damage, is researched by the means of the model test, simulation analysis and theoretical study. Firstly, finite element method and discrete element method are taken to analyze the shear connectors' microcosmic fatigue damage process, and shear connectors' fatigue damage cumulative model as well as the stiffness after fatigue damaged are studied with the help of fatigue testing results. And then, according to the load balance and displacement compatibility conditions, the load-transmitting deterioration mechanism of shear connector group is propounded. The shear stiffness evolution model of shear connector group is proposed after comparing with the fatigue testing results. Taking account of above-mentioned research results, the shear connectors' fatigue damage caused additional deflection calculation methods of steel-concrete composite beam bridge are proposed, and proved by the fatigue tests. Finally, the steel-concrete composite beam bridge's stiffness degradation mechanism resulted from shear connectors' fatigue damage, and the long-term deflection calculation methods considering the load history and structural form, are proposed. The research results can provide evidence and guidance for further exploration on the durability and long-term performance of steel-concrete composite beam bridge.

剪力连接件的疲劳损伤会引起钢-混凝土组合梁桥的刚度退化,影响行车舒适性、安全性甚至结构安全。在总结既有研究成果的基础上，通过理论研究、仿真分析与模型试验，对剪力连接件疲劳损伤导致的钢-混凝土组合梁桥的刚度退化机理进行研究。首先采用有限元法与离散单元法对剪力连接件的微观疲劳损伤过程进行分析，并结合疲劳试验结果，研究剪力连接件的疲劳累积损伤模型以及疲劳损伤后的剩余刚度；在此基础上，基于剪力连接件集群的荷载平衡与变形协调条件，分析其疲劳损伤后传力性能的劣化过程，与疲劳试验结果对照，提出剪力连接件集群的抗剪刚度演化模型；将上述研究成果引入钢-混凝土组合梁挠度计算理论中，提出由剪力连接件疲劳损伤所致的附加挠度计算方法并加以试验验证，阐明钢-混凝土组合梁桥的刚度退化机理，提出考虑荷载历程与结构形式的钢-混凝土组合梁桥长期挠度计算方法。研究成果可以为钢-混凝土组合梁桥的耐久性与长期使用性能研究提供参考。

剪力连接件的疲劳损伤会引起钢-混凝土组合梁桥的刚度退化,影响行车舒适性、安全性甚至结构安全，本项目通过理论研究、仿真分析与模型试验，对剪力连接件疲劳损伤导致的钢-混凝土组合梁桥的刚度退化机理进行研究。首先通过数值分析及疲劳试验，研究了栓钉和PBL剪力键等常用剪力连接件的疲劳累积损伤模型以及疲劳损伤后的剩余刚度；在此基础上，基于剪力连接件集群的荷载平衡与变形协调条件，分析其疲劳损伤后传力性能的劣化过程，与疲劳试验结果对照，提出剪力连接件集群的抗剪刚度演化模型；设计了3片钢-混凝土组合梁的疲劳试验，研究了剪力连接件疲劳损伤导致的钢-混凝土组合梁疲劳损伤机理以及梁的刚度退化机理，并与推到得到的长期刚度计算模型进行了对比验证。研究成果可以为钢-混凝土组合梁桥的耐久性与长期使用性能研究提供参考。