钢混组合梁桥复合粘结锚固抗剪连接的界面力学特性及疲劳劣化机理研究

When hybrid bonding with both epoxy mortar layer and stud shear connectors are used in steel-concrete composite bridge, mechanical behavior of the interface between concrete slabs and epoxy mortar layer and between steel girder flanges and epoxy mortar layer is relatively complex. This complex interfacial mechanical behavior is of great important in the analysis of composite bridge. Through tensile test and compression (tension)-shear coupling test, the coupling mechanical behavior of the interface was obtained, and parameters of cohesive zone model were calibrated. With both experimental and numerical study, mechanisms of shear stress delivery and failure mode for the hybrid bonding system were provided. And improvement on stress concentration for stud shear connectors caused by the epoxy mortar layer was evaluated. Experimental study of fatigue behaviors of the hybrid bonding system was carried out. Fatigue degradation mechanism of hybrid bonding interface was investigated. The fatigue life of steel-concrete composite structure under service load is supposed to be improved. Based on VFEAP program, nonlinear enhanced finite element model with separated mathematical and physical mesh was developed to simulate the nonlinear mechanical behavior of the interface, and was applied for the analysis of actual composite bridge. It is of great significance for the design of shear connectors and bonded interface, and for the improvement of the durability of composite bridge.

组合结构桥梁采用环氧砂浆抗剪连接层和栓钉复合粘结锚固时，抗剪连接界面的压（拉）剪耦合非线性力学行为复杂，且对桥梁结构的准确分析评估具有重要影响。本项目通过压（拉）剪试验研究，揭示复合粘结锚固抗剪连接中的环氧砂浆抗剪连接层与混凝土板和钢翼缘板之间界面在压（拉）剪耦合条件下的粘结滑移关系，并对界面粘聚区域模型参数进行标定。结合试验研究和数值模拟，提出复合粘结锚固抗剪连接的剪力传递机制和破坏机理，分析环氧砂浆抗剪连接层改善栓钉局部应力集中的效果。开展设置环氧砂浆抗剪连接层和栓钉的复合粘结锚固抗剪连接的疲劳试验研究，揭示复合粘结锚固抗剪连接的疲劳劣化机理，提升组合结构在正常使用极限状态下疲劳寿命。基于VFEAP程序，开发考虑界面非线性力学行为的物理网格和数学网格分离的非线性强化有限元，并应用于实际桥梁的分析评估。本项目研究对优化抗剪连接件的布置形式及结合界面设计、提高组合梁桥疲劳寿命具有重要意义。

组合结构桥梁采用环氧砂浆抗剪连接层和栓钉复合粘结锚固时，抗剪连接界面的压（拉）剪耦合非线性力学行为复杂，且对桥梁结构的准确分析评估具有重要影响。建立了考虑组合梁界面滑移的静动力数值分析模型，并分析抗剪连接件非线性抗剪刚度的影响，对栓钉的布置进行优化分析。针对预期研究内容，开展复合粘结锚固抗剪连接界面力学特性的试验研究，探析环氧砂浆结合界面层与钢及混凝土板之间的粘结性能，获取结合界面剥离破坏规律及界面的粘结滑移关系，并研究结合界面法向压应力对粘结性能的影响。进行了同时设置环氧砂浆粘结层和栓钉的复合粘结锚固抗剪连接的试验研究，考察不同环氧砂浆抗剪连接层厚度对抗剪连接力学性能的影响规律，分析加载时界面剪力分布、荷载-滑移关系、破坏形态，通过试验研究复合粘结锚固抗剪连接试件加载时的剪力传递机制及破坏机理。复合粘结锚固抗剪连接中的环氧砂浆抗剪粘结层能较好地和栓钉协同工作，在达到抗剪承载力前结合界面不会过早剥离。复合粘结锚固抗剪连接可以改善栓钉在运营过程中受力时的应力集中状态，可提升组合梁结构在运营过程的疲劳寿命。