To study the effect of structural parameters on the dynamic characteristics of through concrete-filled steel tube (CFST) arch bridges, a through CFST arch bridge with span arrangement 2×125 m was cited as an example and analyzed, the model of the bridge was set up by the software ANSYS and the first 6 orders of natural vibration frequency and the corresponding vibration modes of the bridge were calculated. The results of the calculation show that the vibration of the bridge has both the individual in-plane and out-of-plane vibration and also the inplane and out-of plane vibration coupling. The effect of the structural parameters, such as the steel content ratio of the main arch rings, sectional area and arrangement of the wind bracings,in-plane initial deflection of the arch ribs, deck width and rise-to-span ratio, on the dynamic characteristics was analyzed. The results of the analysis show that the increase of the steel content ratio, the rational arrangement of the wind bracings and the appropriate decrease of the rise-to-span ratio can effectively increase the structural rigidity of the bridge, the effect of the in-plane initial deflection of the arch ribs on the dynamic characteristics of the structure can be ignored and the excessive width of the deck will decrease the rigidity of the structure, which requires that the cross ties should be appropriately reinforced.%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.
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