高速铁路无砟轨道矮塔斜拉桥竖向变形研究

Research on Vertical Deformation of Extradosed Cable Stayed Bridge on Ballastless Track of High Speed Railway

为了研究高速铁路无砟轨道矮塔斜拉桥梁体竖向变形规律,以长沙湾特大桥主桥为背景,利用Midas软件建立有限元模型,对拉索索力、温度荷载、混凝土收缩徐变等参数进行计算与分析,研究其对梁体竖向变形的影响。研究结果表明:索梁温差对中跨竖向变形的影响极其敏感,在塔梁与拉索温差引起的温度耦合效应下,索梁温差从0℃增长至10℃,中跨跨中位置处竖向变形近似呈线形增长趋势;加载龄期延长至14 d对中跨梁体竖向变形有明显的抑制作用,加载龄期从5 d增长至28 d,成桥10年边跨竖向变形曲线基本重合,梁体中跨跨中位置处的竖向变形最大减小量为2.7 mm,14 d加载龄期时减小量为2.4 mm;因年平均相对湿度变化引起梁体变形主要取决于收缩效应,当年平均相对湿度从50%增长至90%时,徐变效应引起的梁体最大竖向变形仅减小了2.7%,收缩效应引起的梁体最大竖向变形减小了69.1%;成桥后随着运营时间的增长梁体竖向残余变形呈现出先增长后减小的规律,成桥5年时梁体中跨跨中竖向残余变形达到峰值+15.43 mm,成桥30年时变形量减小到+7.49 mm。结论可为矮塔斜拉桥的设计和线形控制提供理论参考。

The paper is intended to study how the beams of ballastless track extradosed cable stayed bridges of high speed railroad deform vertically.With the main bridge of Changshawan Grand Bridge as the research object,the Midas software was used to establish a finite element model,with which its parameters such as cable force,temperature load,and shrinkage and creep of concrete were calculated and analyzed.The effects of these parameters on vertical deformation of the beam were studied,with the following conclusions reached.(1)The mid span vertical deformation is extremely sensitive to the temperature difference of the cable beam.Under the temperature coupling effect caused by the temperature difference between the tower beam and the cable,the temperature difference of the cable beam grows from 0℃to 10℃.The vertical deformation at the mid span span position grows linearly.(2)The extension of the concrete age of loading to 14d has a significant inhibitory effect on the vertical deformation of the mid span girders.When the concrete age of loading increases from 5 d to 28 d,the vertical deformation curves of the side spans basically coincide with each other for 10 years.The maximum reduction of vertical deformation at the mid span span position of the beam is 2.7 mm,and the reduction at the concrete age of loading at 14 d is 2.4 mm.(3)The beam deformation due to RH changes depends mainly on the shrinkage effect.When RH increases from 50%to 90%,the maximum vertical deformation of the bridge caused by creep effect decreases by only 2.7%,and the maximum vertical deformation of the bridge caused by the shrinkage effect drops by 69.1%.(4)After the completion of the bridge,the vertical residual deformation of the girders will grow first and then decrease.The mid span vertical residual deformation of the girders reached the peak of+15.43 mm five years after the bridge was completed.The deformation decreased to+7.49 mm 30 years after the completion of the bridge.The conclusions can provide theoretical reference for the design and linear control of extradosed cable stayed bridges.