安装固定气动翼板的大跨桥梁抖振分析

COUPLED BUFFETING ANALYSIS OF LONG SPAN BRIDGES WITH STATIONARY AERODYNAMIC WINGS *>

建立了安装固定气动翼板的大跨桥梁多模态耦合抖振分析框架,推演了作用在整个桥梁-气动翼板系统上的抖振力和自激力的显式表达式,考虑了多模态耦合效应.基于有限元法,作用在主梁-气动翼板系统上的抖振力转化为节点力,进一步得到作用在整个桥梁上的抖振力并导出了其功率谱密度矩阵;作用在主梁-气动翼板系统上的气弹自激力转化为节点力,并将其表达为气弹刚度矩阵和气弹阻尼矩阵.通过组集得到系统的运动方程,然后运用虚拟激励法在频域计算系统的抖振响应.以某大跨斜拉桥为例进行研究,结果表明:在主梁下方安装一对固定气动翼板后,主梁的扭转角位移、角加速度以及侧向加速度响应能够得到有效控制.

A framework for coupled buffeting analysis of long span bridges with stationary aerodynamic winds is presented, in which the buffeting and aeroelastic forces on the whole deck-wings system are derived and both given in explicit forms, and the dynamic coupling between modes of vibration are taken into consideration. Based on the finite element method, the buffeting forces on the whole deck-wings system are converted into nodal forces to obtain a load vector on the entire bridge and the power spectral density matrix of the buffeting force vector is derived, the aeroelastic forces on the whole deck-wings system are converted into nodal forces and further expressed in terms of aeroelastic stiffness and damping matrices. After the system equation of motion is assembled, the pseudo excitation method is applied to execute the buffeting analysis of the system in the frequency domain. A long span cable-stayed bridge is taken as a case study, the results show that: the torsional buffeting displacement, the torsional and lateral acceleration responses can be controlled efficiently with a pair of stationary aerodynamic wings attached beneath both edges of the bridge deck.