下承式铁路钢桥的病害原因分析及加固措施论证

研究目的下承式铁路钢桥在其腹部、底板和横梁上出现裂纹和腐蚀面,这是该种钢桥在服役多年后普遍存在的病害。本文将寻求对病害原因的全面认识。研究方法利用有限元软件,对该钢桥进行结构受力分析,通过化学实验对钢材进行化学成份分析,并对裂纹位置进行了疲劳结算,对所采取的加固措施进行了可行性论证。研究结论(1)纵梁腹板水平裂纹系被硬物划伤所致,纵梁端截面处的腹板下部竖向裂纹是疲劳引起的。(2)下平纵联节点板呈现的层状撕裂是由于材质不合格及冶炼时层间夹碴引起的。(3)桥梁上的腐蚀凹面是列车上的污物掉落在桥上长期腐蚀的结果。(4)现行采用的在裂纹部位粘贴钢板加固纵梁的方法,改变了纵梁的内力分布,改善了纵梁的应力水平,使钢桥满足了承载能力的要求。

ANALYSIS OF CAUSES FOR DISASTER OF ONE RAILWAY STEEL BRIDGE AND DEMONSTRATTON OF REINFORCEMENT MEASURES FOR BRIDGE

Research purposes:Cracks and etched surface occur on the web,bottom plate and cross beam of bottom railway steel bridge.These are the common disasters after the bridge services for many years.The overall understanding of causes for the disaster is sought in this paper. Research methods:The structure stress analysis is made to the bridge by adopting finite-element software.The fatigue estimation is made to the crack position and the feasible demonstration is done to the reinforcement measures through analysis of chemical constitution by doing chemical experiment to the steel. Research conclusions:(1)The horizontal crack on the web plate of longitudinal beam is caused by damage by hard matter and the bottom vertical crack on the web plate in end section of longitudinal beam is caused by fatigue.(2)The bedded crack on low plain longitudinal node plate is caused by rejected steel quality and slag inclusion in interlayer while smelting.(3)The etched concave surface on cross beam is caused by long-time erosion of sewage on the bridge dropping from train.(4)The internal force distribution of longitudinal beam is changed and stress level of longitudinal beam is improved by adopting the method of pasting steel plate on crack position for reinforcing longitudinal beam. In this way,the bridge can meet the requirement of bearing capacity.