箱梁悬臂板局部振动特性及其对列车走行性影响

摘要

以上海长江大桥引桥为背景,运用基于模态叠加的车桥耦合振动分析方法,研究箱梁悬臂板在列车作用下的局部振动特性及其对列车走行性的影响.研究结果表明:实体有限元箱梁模型能反映传统杆系有限元模型不能考虑的悬臂板局部振动响应,而且杆系有限元模型的计算结果低估了车桥振动响应;采用钢管加劲撑或者防掩护栏加强措施对悬臂板的局部刚度均有一定的提高,但防掩护栏拼施比钢管加劲撑措施更利于行车安全;当悬臂板自振频率较低而列车车速较高时,可能产生显著的悬臂板局部共振响应;一般箱粱悬臂板上可以适合车速较低的城市轨道交通列车运行,但不能满足高速列车正常行驶要求.%A mode superposition based train-bridge dynamic interaction analysis method was proposed and applied to study the local vibration of a box girder cantilever plate under the action of train and its influence on the ride quality of the train passing through it. The box girder bridge approaches of Shanghai Yangtze'River Bridge was selected to conduct the case study. The calculation results show that the box girder model with the solid finite element box girder model could reflect the local vibration responses of the cantilever plate which might be ignored by the traditional spatial beam element model. The vehicle-bridge dynamic response was underestimated by using the spatial beam element model. Two design schemes for strengthening the cantilever plate were comparatively studied. It is found that the steel tube bracket scheme and the concrete crash barrier scheme both can improve the local stiffness of the cantilever plate while the latter is a little better for train running safety. Significant local resonant responses of the cantilever plate can be observed when the natural frequencies of the cantilever plate are much lower and the train speeds are much higher. It can be concluded that the cantilever plate of the box girder is generally suitable for the operation of urban rail transit trains but not adequate for the normal operation of high speed trains.