大跨度铁路钢桁梁斜拉桥竖向刚度评估方法研究

Study of Vertical Stiffness Evaluation Method of Long-Span Steel Truss Girder Cable-Stayed Railway Bridge

为评估超出铁路桥涵设计规范中规定跨度的桥梁的竖向刚度合理性,提出基于弦测法幅值与车体加速度关系和车-桥耦合振动分析的大跨度桥梁竖向刚度快速评估方法。首先基于弦测法确定控制弦长,分析设计车速下弦测法幅值与车体加速度关系,根据车体加速度限值相关规定确定弦测法幅值限值;再采用车-桥耦合振动分析得出列车通过大桥的车体响应并反算得到对应弦测法幅值,叠加各因素引起的桥面变形的弦测法幅值后与弦测法幅值限值对比,对桥梁竖向刚度进行评估。采用该评估方法对某时速200 km的(36+96+228+96+36)m大跨度铁路钢桁梁斜拉桥竖向刚度进行评估,结果表明:控制弦长为30 m时可较好反映时速200 km的铁路桥梁竖向变形与车体竖向加速度的对应关系;此条件下考虑升、降温引起的附加不平顺后,双线客车作用下弦测法幅值为7.6086 mm,满足日常保养标准;一线客车一线货车作用下,弦测法幅值为14.7426 mm,略高于计划维修标准但满足临时补修标准。

A method that can rapidly evaluate the vertical stiffness of long-span bridges is presented,aiming to judge the effectiveness of vertical stiffness of bridges that exceeds the stipulated values in the related design specifications of railway and culverts.The method is developed based on the consideration of the relationship between chord measurement value and vehicle acceleration as well as the vehicle-bridge coupling vibration analysis.First,the control chord length is determined by the chord measurement method,with which,the relationship between chord measurement value and vehicle acceleration under design vehicle speeds is analyzed,and the limit of chord measurement value is determined in accordance with the related stipulated vehicle acceleration limits.Second,the vehicle and bridge coupling vibration is analyzed to obtain the dynamic responses of vehicles when passing through a bridge,and the corresponding chord measurement values are gained via inverse calculation.The chord measurement values of deck deformation induced by diverse factors are superimposed and compared with the limit of the chord measurement value,so that the vertical stiffness of the bridge could be evaluated.The presented method has been used to evaluate the vertical stiffness of a long-span steel truss girder cable-stayed railway bridge that has a central span of 228 m,two side spans of 96 m and two secondary side spans of 36 m,with a service speed of 200 km/h.It is shown that for the railway bridge with service speed of 200 km/h,when the control chord length is set at 30 m,the relationship between the vertical stiffness of the bridge and vehicle acceleration can be better revealed.By considering this,the additional irregularity induced by temperature fluctuation is taken into account,as a result,a limit of 7.6086 mm of chord measurement value under double-track passenger vehicles is obtained,which meets the routine maintenance standard.While under a passenger vehicle on one line and freight vehicle on the adjacent line,the chord measurement value is 14.7426 mm,a bit higher than the planned maintenance standard,but meets the temporary repair standard.