列车移动荷载作用下大跨度悬索桥纵向位移控制研究

Longitudinal Displacement Control of Long-Span Suspension Bridge Under Moving Train Loads

为有效控制列车移动荷载作用下大跨度悬索桥梁端产生的纵向位移,以某大跨度铁路悬索桥为背景,采用非线性动力时程分析法,考虑几何非线性和边界非线性,研究在货运列车移动荷载作用下,改变结构体系和约束体系对悬索桥纵向位移的控制效果。结果表明:结构体系方面,设置中央扣和水平拉索均可增大悬索桥结构纵向刚度,显著减小梁端纵向位移;设置中央扣还可减小缆、梁端纵向位移差,对纵向位移控制效果更优。约束体系方面,随着粘滞阻尼器速度指数减小,梁端纵向位移峰值逐渐减小;磁流变阻尼器对梁端纵向位移控制效果有限。采用2种阻尼器组合约束可控制列车过桥纵向位移同时不显著增加缆、梁端纵向位移差。

An existing long-span railway suspension bridge is used as a case to study the effective measures to control the oversized girder-end longitudinal displacement of the bridge of such type under moving train loads.With an nonlinear dynamic time-history analysis method,the effects of changing structural system and restraint system to control the girder-end longitudinal displacement of a suspension bridge under moving freight train loads were analyzed,considering the geometrical nonlinearity and boundary nonlinearity.It is shown that adding a central buckle and horizontal cables can improve the longitudinal stiffness of the stiffening girder and in turn alleviate the girder-end longitudinal displacement.The central buckle can also reduce the difference between the longitudinal displacements of the main cables and the girder-end longitudinal displacement,exhibiting better longitudinal displacement control effect.As the velocity exponent of the viscous dampers decreases,the peak values of girder-end longitudinal displacement gradually go down.The control effect of the magnetorheological dampers on the girder-end longitudinal displacement is limited.The combined utilization of these two types of dampers can effectively control the girder-end longitudinal displacement while train passing,but does not significantly enlarge the displacement difference between main cables and girder ends.