大跨铁路斜拉桥模态特性研究

建立了大跨铁路斜拉桥的三维有限元整桥模型。利用子空间迭代法求解无阻尼自由振动的特征方程。分析计算了整桥频率和有车频率及其振型的变化趋势,模拟计算结果显示各阶有车整桥频率低于相应的无车整桥频率,并且振型也由整桥无车时,垂直面与水平面两个独立平面的振动,演变成有车时,竖向挠曲与横向弯扭的空间藕合,研究了不同停车位置和不同列车长度对斜拉桥的自振频率的影响,随着停车位置的变化,有车整桥频率发生波动,列车进桥、出桥时,整桥频率分别单调下降、上升;列车停于桥中和桥塔处,整桥频率出现驻值点,随着拖车数目的变化,有车整桥频率亦发生变化,一般趋势是:随着拖车数目的增加各阶有车整桥频率将会降低,而其变化趋势不受拖车数目影响。

Modal characteristics of a large span railway cable-stayed bridge

A 3D finite element model of a whole bridge was built up. The characteristic equation of its free vibration was solved with subspace iteration method. The changing trend of natural frequencies and vibration modes of the whole bridge without or with a train was computed and analysed. The results of simulation and calculation showed each natural frequency of the whole bridge with a train was lower than the corresponding one of the whole bridge without a train. Moreover, vibra-tion modes were changed into spatial coupled modes of vertical bend and lateral bend and torsion from ones in independent vertical and horizontal planes. The influences of the train different parking position and diffenert length on natural frequen-cies of the cable-stayed bridge were also studied. With change of parking positions, natural frequencies of the whole bridge with a train fluctuated. When the train entered or left the bridge , natural frequencies of the whole bridge monotonously dropped or rose respectively; when the train stopped in the middle of the bridge or near the bridge tower, natural frequencies of the whole bridge would have extreme points. With variety of the number of trailing vehicles, natural frequencies of the whole bridge changed too. It was shown that natural frequencies of the whole bridge should drop while the number of trai-ling vehicles increased. However, the changing trend of natural frequencies was not influenced by the number of trailing vehicles.