Vibration control of cable-stayed bridges—part 2: control analyses

Abstract

The objective of this research is to increase the understanding on how the complexities associated with modelling cable-stayed bridges, such as non-linear behaviour and the participation of coupled, high-order vibration modes in the bridge's dynamic response, affect the overall effectiveness of active control schemes. Using a reduced-order state-space model, control analyses examine the effectiveness of full state feedback control employing a Linear Quadratic Regulator (LQR) and the effectiveness of dynamic output feedback control utilizing a Kalman–Bucy filter in attenuating the structure's force time-history response. Results show that significant reductions of the maximum internal forces and the force/displacement response can be achieved through full state or output feedback control. An investigation of various actuator configurations leads to the conclusion that actuators are most effective when located close to the centre of the bridge span. The study also shows that only first-order modes need to be controlled to reduce the displacement response; however, the control of higher-order modes is essential to reduce the force response. Multiple-support excitation needs to be considered since it can excite entirely different modes than uniform-support excitation. Moreover, multiple-support excitation induces forces that are caused by pseudo-static displacements and can not be controlled. Special attention needs to be given to coupled modes since their control can lead to an increased force response of the structure. © 1998 John Wiley & Sons, Ltd.