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为研究结构参数对下承式钢管混凝土拱桥动力特性的影响,以某跨径为2×125 m的下承式钢管混凝土拱桥为例进行分析。采用ANSYS建立该桥模型,计算桥梁前6阶自振频率及相应振型,计算结果表明:该桥型的振动既有单独的面内和单独的面外振动,也有面内和面外的振动耦合。分析主拱圈含钢率、风撑截面积及布置形式、拱肋面内初始挠度、桥面宽度、矢跨比等结构参数对该桥动力特性的影响,分析结果表明:增加主拱圈含钢率、合理设置风撑和适当降低矢跨比能有效提高下承式钢管混凝土拱桥的结构刚度;拱肋面内初始挠度对结构动力性能影响可以忽略不计;桥面过宽会降低结构刚度,需要适当加强结构的横向联系。
In order to study the influence of structural parameters on the dynamic characteristics of CFST arch bridge, a concrete-filled CFST arch bridge with a span of 2 × 125 m is taken as an example. The bridge model was established by ANSYS to calculate the natural frequency and the corresponding mode shape of the first six steps of the bridge. The calculation results show that the vibration of the bridge has both in-plane and out-of-plane vibration alone and in-plane and out-plane vibration coupling. The influence of the structural parameters such as the steel ratio of the main arch, the cross-sectional area and layout of the wind arch, the initial deflection in the arch rib, the width of the bridge deck and the ratio of the span to the span on the dynamic characteristics of the bridge is analyzed. The results show that: Steel ratio, proper setting of wind-support and proper reduction of ratio of sag to span can effectively improve the structural rigidity of CFST arch bridges. The initial deflection in the arch surface can have negligible effect on the dynamic performance of the structure. The horizontal linkage of the structure needs to be appropriately strengthened.