大跨度连续刚构柔性拱组合结构受力效应分析

为研究大跨度连续刚构柔性拱组合结构受力效应,以宜万铁路宜昌长江大桥为背景,在总结该类结构体系特点的基础上,采用桥梁博士分析软件建立全桥平面有限元模型,对全桥桥面施加竖向均布荷载(二期恒载),分析拱梁内力、竖向荷载及跨中截面弯矩的分配;将该桥与孔跨组成及截面尺寸完全相同的连续刚构桥在恒、活载作用下的结构内力进行对比,分析组合结构的拱梁组合效应。分析结果表明:在竖向均布荷载作用下,连续刚构柔性拱组合结构跨中范围吊杆轴力增加较大;结构跨中截面总弯矩绝大部分已转化为拱肋压力与主梁拉力;与连续刚构相比,活载作用下,连续刚构柔性拱组合结构的主梁弯矩显著减小,结构刚度提高较大,柔性拱作用明显。

Analysis of Force Effect of Long Span Hybrid Structure of Continuous Rigid-Frame and Flexible Arch

To study the force effect of the long span hybrid structure of continuous rigid-frame and flexible arch,the Yichang Changjiang River Bridge on Yichang-Wanzhou Railway was cited as example.On the basis of summarization of the characteristics of such type of the structure system,the analysis software Bridge Doctor was used to establish the planar finite element model for the whole bridge of the bridge,the vertical uniform load(the second phase dead load) was applied to the deck of the whole bridge and the distribution of internal forces,vertical load and midspan section bending moment of the arch and girder of the bridge was analyzed.The structural internal forces of the bridge under the action of static and dynamic loads were compared to those of a continuous rigid-frame bridge having completely the same span compositions and sectional dimensions and the effect of the hybrid structure of the arch and girder was analyzed.The results of the analysis demonstrate that under the action of the vertical uniform load,the increase of the hanger axial forces in the range of the midspan of the hybrid structure of the continuous rigid-frame and flexible arch is great,most of the total bending moment of the midspan section has been transferred to the compression of the arch ribs and to the tensile force of the main girder.In comparison to the continuous rigid-frame bridge,the bending moment of the main girder of the hybrid structure under the action of live load is considerably reduced,the structural rigidity is greatly increased and the function of the flexible arch is evident.