铁路连续槽形梁桥静力特性分析

Analysis of Static Property of Continuous Trough Girder Railway Bridge

为给铁路连续槽形梁桥结构简化计算和优化设计提供理论依据,以某(40+64+40) m箱形截面铁路连续槽形梁桥为背景,进行铁路连续槽形梁桥静力特性分析。采用ANSYS软件建立该桥空间实体有限元模型,分析桥梁变形、控制截面应力分布、边梁和道床板的受力特点以及边梁和道床板分担纵向弯矩的比例,并对不同截面槽形梁桥的边梁与道床板承担纵向弯矩比例进行对比。结果表明:在恒载及列车活载作用下,中支座附近边梁向槽内倾斜,槽口减小;主跨跨中和边支座附近边梁外斜,槽口略微扩大;全桥各截面边梁下缘最大压应力明显大于道床板下缘最大压应力,截面下缘应力分布不均匀现象显著,剪力滞效应突出;该桥边梁和道床板在主跨跨中截面分担纵向弯矩的比例为1.41∶1,在两中支座处截面的分担比例分别为3.78∶1和4.00∶1,主跨跨中截面边梁承担弯矩的比例较低;槽形梁桥边梁与道床板的弯矩分担比例与二者的竖向抗弯刚度比呈正相关;箱形截面槽形梁相较其它截面槽形梁具有更大的抗弯刚度,可实现更大的跨度。

The study in this paper focuses on the simplified calculation and optimized design of the continuous trough girder railway bridge.An existing bridge with three spans of 40,60 and 40 m,consisting of trough girders of box cross-section,is used as a case,based on which the static property of the continuous trough girder railway bridge is analyzed.A solid-element numerical model of the bridge was established in ANSYS,to analyze the deformation of the bridge,stress distribution in control cross-sections,the load bearing behaviors of the edge girders and deck slabs as well as the longitudinal bending moment sharing ratios of the edge girders and deck slabs.It is shown that under dead loads and train live loads,the edge girders in the vicinity of intermediate bearings lean inwardly,making the opening of the trough girder smaller.Whereas the edge girders at the midspan of main span and edge bearings lean outwardly,enabling the opening of the trough girder to expand.The maximum compressive stresses in the lower flanges of the edge girders are obviously bigger than those in the lower flanges of the deck slabs,resulting in uneven stress distribution in the lower flanges of cross sections and significant shear lag effect.The longitudinal bending moment sharing ratio of the edge girders at the midspan of main span and the deck slabs is 1.41∶1,while these ratios of the edge girders at the two intermediate bearings and the deck slabs are 3.78∶1 and 4.00∶1,respectively.The bending moment sharing ratio of the edge girders at the midspan of main span is relatively lower.The bending moment sharing ratios of the edge girders and deck slabs of the trough girder bridge are proportional to the flexural stiffness ratio of the two.Compared with the trough girders with other patterns of cross-sections,the trough girder with box cross-section has greater flexural stiffness,which can be applied to bridges required to have longer spans.