装配式高架栈桥结构模态分析

为了得到装配式高架栈桥结构单元及栈桥的自振特性,对其结构进行了计算简化,利用ANSYS建立了采用不同约束时的数值模型的结构单元,同时使用子空间迭代法计算了数值模型的前十阶频率及振型。基于结构共振特性以及实际工程中架设方便的考虑,确定了桩腿与上部结构固结、与地面铰接这一合理的高架栈桥结构单元约束形式,最后对一个由4个高架栈桥结构单元拼接而成的总长为48m的高架栈桥进行了模态分析,求解了其前十阶频率和振型。通过对频率及振型的分析,得出桩腿是此高架栈桥的薄弱部位,为避免共振,车辆不宜以5km/h左右的速度通过栈桥。

Modal analysis of fabricated elevated trestle

To obtain the natural vibration characteristics of the unit of fabricated elevated trestle and trestle, the simplified calculation model for the trestle was employed. The numerical models using four different constraints were established by ANSYS, and the first ten ranks of natural frequency value and the modal vibration type of the above four structural modals were calculated by using the subspace iteration method. Considering the resonant properties and the convenience of the erection process of the trestle, the leg concreting with the superstructure as well as hinging with the ground for the trestle unit was considered as the reasonable connecting type. Finally, the modal analysis of the total length of 48 m for the trestle model constituted by four unit was simulated, and the first ten ranks of natural frequency value and the modal vibration type of the whole bridge were calculated. The result shows that the leg is the weak component, and the vehicles' speed cannot be 5 km/h or so in order to avoid the sympathetic vibration.