系杆拱桥拱脚等效静力刚度及其对全桥力学性能的影响研究

Research on Equivalent Static Stiffness of Arch Foot and its Influence on Mechanical Behavior of Tied Arch Bridge

目前在系杆拱桥全桥有限元模型中,拱脚多采用与拱肋相一致的刚度,使得荷载响应与实际结构有显著差异。为得到更真实的系杆拱桥荷载响应,通过建立具有可比性的拱脚局部精细化实体模型和变刚度的局部杆系模型,定义基于位移响应差值的等效静力刚度指标,提出了适用于系杆拱桥拱脚的等效静力刚度理论。作为一个应用实例,将上述理论应用于罗蕴河拱桥的全桥力学性能分析中,结果表明在不考虑该理论的情况下,拱肋挠度验算过于保守,而吊杆的疲劳验算则偏不安全。提出的拱脚等效静力刚度理论将为系杆拱桥吊杆疲劳性能研究提供一定的理论基础。

In most current finite element（FE）models of tied arch bridges,the stiffness of the arch foot is taken the same as that of the arch rib,which may result in significant differences in loading responses between the FE model and the real structure.To obtain a more realistic loading response of the arch bridge,the local entity model and comparable truss model with a variable stiffness are built,an index based on the difference of the displacement response is defined to determine the equivalent static stiffness of the arch foot.By these approaches,the theory of the equivalent static stiffness which is suitable to the arch foot of tied arch bridges is finally proposed.As an application example,the above theory is applied into the analysis of mechanical behaviors of the Luoyun River arch bridge.The results show that without the consideration of the theory,the deflection check of the arch rib is too conservative,while the fatigue check of the hanger rod is unsafe.The proposed theory of the equivalent static stiffness of the arch foot can provide a theoretical base for the research on the fatigue performance of hanger rods of tied arch bridges.