中文摘要：

以在建的洞庭湖铁路三塔斜拉桥为工程背景,分析了箱桁断面斜拉桥主梁的建模方法以及涡激共振性能。首先比较了主梁建模的空间杆系模型、梁壳组合模型以及三维壳体模型在模态频率、主梁单位长度等效质量和等效质量惯性矩的差异。结果表明,三种模型的模态分析结果基本相近,但空间杆系模型不能准确得到高阶侧弯模态的主梁等效质量。继而采用刚性节段模型弹性悬挂风洞试验对箱桁组合主梁涡激共振性能进行了试验研究。研究表明,这类断面在-3°风攻角发生了超过容许幅值的竖向涡激共振,其中开口钢箱梁部分是诱发涡振的原因。最后进行了气动措施抑振试验,结果表明：在开口钢箱梁桥面板下缘设置两道下稳定板可以显著降低涡振振幅,即当稳定板高度为箱梁梁高一半时,涡振振幅降低至规范容许值以下;当稳定板高度与箱梁等高时,涡激振动现象消失。

英文摘要：

The cable-stayed Dongting Lake railway bridge under construction was case-studied in this paper. A finite element modeling of the cable-stayed bridge with box-truss composite girder and its vortex-induced vibration were analyzed. Three finite element schemes for modeling box-truss girder of the bridge,namely the spatial beam model（ SBM）,spatial plate-beam model（ SPBM） and spatial shell model（ SSM）,were compared in terms of modal frequency,equivalent mass and mass moment of inertia perunit length. It shows that the results from the SPBM and the SSM are basically the same,while the SBM can＇t accurately produce the equivalent mass unit length girder for some higher-order lateral modes. T he vortex-induce vibration of the box-truss composite girder was tested in wind tunnel by flexibly mounted rigid sectional model tests. The results indicate that this cross-section type may experience large-amplitude vertical vortex-induced vibrations at wind attack angle of - 3°,which is caused by the vortex shedding at the leading edge of the box-girder part of the cross-section. The effects of aerodynamic appendix for suppression of vortex-induced vibrations were studied and it is found that two stabilizers beneath the open orthotropic deck dram atically reduce the vibration amplitude. The vibration amplitude is within the limit given in design specif ication when the height of stabilizers is half of the box-girder height; and the vortex-induced vibrations completely diminish when the height of stabilizers is the same as the box-girder height.