针对列车提速的32 m梁加固方案比选

研究目的：为避免发生桥梁结构的局部疲劳损伤以及车桥共振现象,保证桥梁结构具有足够的整体刚度和安全运营性能,同时满足列车舒适度的要求,有必要对现有桥梁进行加固。 研究方法：针对影响结构自振频度的因素并结合桥梁的实际情况,提出了几种不同的桥梁加固方案.在采用有限元方法进行模态分析之后,考虑了施工的可行性,对各方案进行了比选,提出了较为合理的加固方案。 研究结果：桥梁在车辆动荷载作用下将发生振动,目前既有线上的铁路桥梁是基于修建时设计时速进行动力设计和评估的.当列车速度提高以后,车辆激振的频率发生变化,桥梁结构的响应也相应改变.通过测试发现提速后现有桥梁的主要问题在于一阶横向自振频率偏低,桥梁横向振幅偏大。 研究结论：从影响桥梁结构固有频率的因素出发,通过有限元计算可以知道扩大横隔板和增加支架对于提高横向频率来说都是有效的加固手段.从整体效果而言,方案二的加固效果最好,而将混凝土支架替换为角钢与混凝土结合的支架同样能满足要求,同时在既有桥梁上完成这样的加固也是可行的,因此,建议使用第五种方案进行加固。

COMPARISON AND SELECTION OF REINFORCEMENT SCHEME FOR 32 M-SPAN GIRDER TO MEET REQUIREMENT OF TRAIN SPEED-RAISE

Research purposes: To avoid the existences of local fatigue damage of bridge structure and resonance vibration of train and bridge,to guarantee the integrated rigidity of bridge structure and its good working performance and to meet the requirement of comfortableness,it is necessary to reinforce the bridge. Research methods: Several different reinforcement schemes for bridge are proposed according to the influencing factors on natural vibration frequency of structure and in combination with the real situation of bridge. The comparison and selection of schemes are made and rational scheme is decided after the modal analysis is carried out by finite-element method and construction feasibility is considered. Research results: Bridge will vibrate with the effects of train dynamic load. The present dynamic design and evaluation are made to the bridges on existing railway lines based on the design speed per hour of train in construction time. After train speeds up,the shock excitation frequency of train changes,along with it the response of bridge structure also changes. After testing,it is found that the main problems of existing bridge are as follows:the univalent lateral natural vibration frequency is over low and the bridge lateral amplitude of vibration frequency is over low and the bridge lateral amplitude of vibration is over large. Research conclusions: It is known from the calculation made by finite-element method that enlarging cross slab and adding support are good ways to increase lateral frequency,aiming at influencing factors on fixed frequency of bridge structure. Generally speaking,the integrated reinforcement result of Scheme 2 is best. However,it is feasible to complete such reinforcement to existing bridge by replacing concrete support with angle steel-concrete support,which can meet the same requirements. Therefore,it is recommended to adopt Scheme 5 for reinforcement.