设计荷载作用下大跨度铁路悬索桥的梁端变位特征

以连(云港)镇(江)铁路五峰山长江大桥为工程背景,基于有限元分析,研究该桥在基础不均匀沉降、温度荷载、风荷载、竖向活载及制动力作用下的梁端变位特征及荷载组合效应。结果表明:梁端纵向位移主要影响因素为温度荷载和竖向活载,其次为纵向风荷载、基础沉降和列车制动力;梁端竖向转角受竖向活载和基础不均匀沉降影响最大;横向极限风荷载和温度荷载对梁端横向位移和转角存在一定影响;主、引桥之间的横向位移差引起梁端横向折角。除考虑梁端纵向位移和竖向转角外,铁路悬索桥在设计时也应关注梁端横向位移和横向折角,可通过结构约束体系、端横梁局部合理设计及主、引桥支座位置优化等措施满足梁端空间变位要求,从而为大位移梁端伸缩装置的设计和梁端区域行车的安全平稳提供有利条件。

Displacement Characteristics at Girder End of Long Span Railway Suspension Bridge Under Design Loads

Taking Wufengshan Yangtze River Bridge of Lianyungang-Zhenjiang railway as engineering background,the displacement characteristics at girder end and load combination effects of the bridge under the actions of uneven settlement of foundation,temperature load,wind load,vertical live load and braking force were studied based on the finite element analysis.The results show that the main factors affecting the longitudinal displacement at girder end are temperature load and vertical live load,followed by longitudinal wind load,foundation settlement and train braking force.The vertical rotation angle at girder end is most affected by vertical live load and uneven settlement of foundation.The transverse ultimate wind load and temperature load have certain influence on the transverse displacement and rotation angle at girder end.In addition to considering the longitudinal displacement and vertical rotation angle at girder end,the transverse displacement and transverse bending angle at girder end should also be paid attention to in the design of railway suspension bridges.The requirements of spatial displacement at girder end can be satisf ied by means of structural restraint system,local rational design at girder end and optimization the locations of the main and approach bridge bearing.It provides favorable conditions for the design of expansion device with large displacement at girder end,and the safe and stable driving at girder end.