铁路小半径曲线转体槽形梁设计研究

Design and Research of Railway Trough Girder for Rotation Construction on Small Radius Curve

新建京通疏解线特大桥为跨越既有大郑线及新建大郑疏解线而设,因纵断面高度控制,主桥采用(40+56+40)m连续槽形梁,位于R=800 m的圆曲线上,转体施工。该桥为小曲线半径的下承式薄壁开口截面,面临合理桥宽、温度荷载、弯扭耦合影响、剪力滞效应及有效宽度确定、曲线梁转体过程中最大悬臂状态的梁体受力及横向偏载影响等问题。通过分析得出:采用接触网支柱设在边主梁顶的布置形式,尽量减小槽内净宽;提出箱形边主梁的温度荷载加载模式,并考虑铺装层降低非线性温差对结构的影响;纵向计算考虑曲线梁弯扭耦合影响,整体指标较好;得出槽形梁剪力滞效应变化规律,有效宽度系数与铁路规范箱梁截面计算公式结果相近;曲线梁最大悬臂转体时考虑横向偏心,施工状态下安全性较好;经局部分析,梁体及转体结构应力状态较为合理。

Due to the elevation control of the longitudinal section,the main bridge of the newly built Jingtong untwining line super large bridge trides over the existing Dazheng line and the newly built Dazheng untwining line,the main bridge of which adopts(40+56+40)m continuous trough girder.The project points located on the circular curve of R equals 800 meters,which is built swivel,and the project is difficult.Through the analysis,it is concluded that the arrangement of contact network column is used to minimize the clear width in trough.The temperature load loading pattern of the box-section edge main girder is proposed,and the effect on structure is considered by the nonlinear temperature difference.The longitudinal calculation considers the influence of the curved girder bending and torsion coupling,and the change rule of shear lag effect of the trough girder is obtained,and the effective width coefficient is similar to the calculation formula results of the box girder section by the railway code.The transverse eccentricity is considered when the maximum cantilever of the curved girder is rotated,the stress state of the beam body and the rotating structure is comparatively rational,and the safety is better.The above research results can effectively guide the design and construction of similar projects.