基于主动翼板的桥梁颤振次最优控制

颤振是大跨度桥梁抗风设计中的关键问题。通过对颤振进行主动控制影响桥梁的气动形态从而改变作用于结构上的气动力,达到抑制颤振的目的,对于大跨度桥梁的颤振控制是行之有效的手段。但是桥梁的颤振主动控制涉及到气动力的获取和控制率的优化问题,迄今未能完全解决。结合桥梁主动控制前期研究并借鉴航空领域中的颤振主动控制原理,研究了基于主动翼板的桥梁颤振控制问题;基于机翼-副翼理论和颤振导数形式给出了流线箱梁-主动翼板的自激气动力表达式,同时考虑主梁钝体特性和其与主动翼板气动干扰效应;由流线箱梁-主动翼板的气动力表达式和试验控制的诉求,采用次最优控制理论,构造基于少数状态变量的桥梁颤振系统反馈控制方程。根据流线箱梁-主动翼板气动力表达式和次最优控制理论,针对平板-翼板和流线箱梁-翼板系统,首先由数值风洞获取系统的气动力,并采用自编程序解算次最优颤振控制律;最后通过计算流体动力学（CFD）流固耦合数值仿真对控制效果进行检验。结果表明：对于平板-翼板系统,基于流线箱梁-主动翼板气动力表达式而获取的颤振导数与理论解吻合,验证了该气动力表达式的准确性,可用于后续控制分析;结合系统的气动力,次最优控制率在超越无控制结构的临界风速下,能够快速抑振。据此,主梁-翼板系统的次最优控制可面向实际抑制桥梁颤振,并提高颤振临界风速。

Bridge Flutter Suppression Using Suboptimal Control Based on an Active Flap

Flutter is a key issue in the wind-resistant design for long-span bridges. Active control has already be proven to be greatly effective for flutter suppression of bridges. When aerodynamic flap is driven by active control algorithm, it changes the aerodynamic forces acting on the wings by altering the aerodynamic shape and thus eliminate flutter. Based on the active control theory and method in aeronautical engineering, this study focuses on flutter suppression of the streamlined box girder with active flaps (deck-flap system). Considering the bluff body characteristics of the girder and the aerodynamic interference between the girder and the flaps, the expression of aerodynamic forces for bridge active control was proposed in the form of flutter derivatives. In consideration of the operability in flutter suppression of a bridge, suboptimal control algorithm was applied to derive the feedback control equations with fewer observable state variables. Both a plate-flap system and a deck-flap system were investigated respectively through CFD numerical simulation. The aerodynamic forces of the systems were obtained, the feedback control law for flutter suppression of the deck-flap system was then calculated and verified through numerical simulation while considering fluid-structure interaction. Results show that the expression of aerodynamic forces can sufficiently describe the characteristics of the streamlined box girder with active flaps. Suboptimal control for the deck-flap system can suppress vibration rapidly and efficiently when the wind velocity exceeds the flutter critical wind velocity of the system without active control.