某磁浮大跨斜拉桥竖向刚度限值研究

以某磁浮轨道交通(40+80+228+228+80+40)m大跨钢箱梁斜拉桥为研究对象,采用有限元软件ANSYS和多体动力学软件UM分别建立桥梁和磁浮列车模型。基于车桥耦合振动方法,针对2列磁浮列车相向行驶并在主跨跨中交会的最不利情形,进行列车以不同速度通过桥梁时不同梁高下车桥系统的动力响应及磁浮大跨桥梁的竖向刚度限值研究。结果表明:磁浮列车的竖向动力响应随车速的增大而显著增大,时速从40 km增大到140 km时,列车竖向动力响应增幅达到120%以上;车体竖向加速度和Sperling指标不是桥梁结构刚度限值的控制因素;磁浮列车的悬浮间隙对梁体刚度变化较为敏感,随着梁体刚度逐步增大,悬浮间隙的波动变小,梁体挠跨比减小约25%,悬浮间隙波动减小幅度达35%,悬浮间隙可作为中低速磁浮大跨桥梁结构刚度限值的控制指标;梁体挠跨比1/3015可作为磁浮大跨桥梁的竖向刚度限值。

Investigation on Limit Value of Vertical Stiffness for a Long-Span Cable-Stayed Maglev Bridge

Taking a(40+80+228+228+80+40)m long-span steel box girder cable-stayed bridge for maglev rail transit as the research object,the bridge and maglev train models were respectively established by using finite element software ANSYS and multi-body dynamics software UM.Based on the vehicle-bridge coupling vibration method,for the most unfavorable case of two maglev trains running in opposite directions and passing each other in the middle of the main span,the dynamic responses of vehicle-bridge system and the vertical stiffness limits of the maglev long-span bridge under different girder heights when trains passing through the bridge at different speeds were studied.Results show that the vertical dynamic response of maglev train increases obviously with the increase of vehicle speed.The vertical dynamic response of train increases by more than 120%when the speed increases from 40 km·h-1 to 140 km·h-1.The vertical acceleration and Sperling index of carbody are not the control factors for the structural stiffness limit of the bridge.The suspension clearance of maglev train is more sensitive to the change of beam stiffness.With the increase of beam stiffness,the fluctuation of suspension clearance becomes smaller.The fluctuation of suspension clearance decreases by 35%when the deflection-span ratio of beam decreases by about 25%.The suspension clearance can be used as the control index for the structural stiffness limit of medium and low speed maglev long-span bridges.The beam deflection-span ratio of 1/3015 can be used as the vertical stiffness limit of the long-span maglev bridge.