铁路混凝土连续梁桥加载方式研究

Study on Loading Mode of Railway Concrete Continuous Girder Bridge

对存在正负影响线的混凝土连续梁桥进行受力分析,我国规定的加载方式与国际铁路联盟的规定有所差异。我国考虑列车编组中存在空车的情况,即在大于15 m的异符号影响线区段施加空车荷载;而国际铁路联盟考虑最不利情况,仅在同符号区段施加列车荷载。针对这种情况,选择我国典型跨度连续梁,进行不同加载方式下桥梁受力性能的对比分析。采用MIDAS/Civil建立连续梁桥模型,对2种加载方式下边跨和中跨的跨中弯矩、支座反力进行计算分析。结果表明,在异符号影响线区段施加空车荷载与否对连续梁桥结构受力性能影响较小,且在异符号影响线区段加载会显著增加设计人员的工作量。建议我国现行设计规范应予以调整,即对于存在正负影响线的混凝土连续梁桥可按最不利情况进行加载,异符号影响线区段不予施加空车荷载。

The loading mode of Chinese code is different from the regulations of the International Union of Railways( UIC).The stress analysis of concrete continuous girder bridge with positive and negative influence lines was carried out. When the negative influence line region is greater than 15 m,the situation of empty train is considered in Chinese code by the way of applying empty train load for the negative influence line region. But in the UIC code,the most unfavorable condition is considered by the way of applying train load only for the positive influence line region. In view of this situation,a comparative analysis of the stress performance of bridge under different loading modes was made by selecting the typical span continuous girder in China. The model of continuous girder bridge was established by MIDAS/Civil,and the bending moment of middle span and bearing counterforce under the two loading modes were calculated and analyzed. The results show that the effect of loading or non-loading the empty train load in the negative influence line regions has little influence on the stress performance of continuous girder bridge,and the load in the negative influence line regions will significantly increase the workload of designers. Therefore, it is suggested that the adjustment should be done to the current design code of China. The concrete continuous girder bridge with positive and negative influence lines can be loaded in the most unfavorable condition,the empty train should not be loaded in the negative influence line region.