Vibration control of network-based offshore structures subject to earthquakes

Abstract

Marine structures are inevitably influenced by parametric perturbations as well as multiple external loadings. Among these loadings, earthquake is generally more destructive and unpredictable than others. It is significant to develop effective active control schemes to guarantee the safety, stability, and integrity of marine structures subject to earthquakes and parametric perturbations. In this paper, the problem of networked ${\mathcal{H}}_{\infty }$ robust damping control is addressed to stabilize a marine structure subject to earthquakes. First, in consideration of perturbations of the structure parameters, an uncertain model of the networked marine structure under earthquakes is presented. Second, a robust networked ${\mathcal{H}}_{\infty }$ control scheme is presented to suppress seismic responses of the structure. By using stability theory of time-delay systems, several sufficient conditions on robust stability of the networked marine structure system are obtained, and the linear matrix inequality methods are utilized to solve the gain matrix of the controller. Finally, simulation indicates that compared with the traditional robust ${\mathcal{H}}_{\infty }$ control and the proposed networked ${\mathcal{H}}_{\infty }$ control, the seismic responses amplitudes of the marine structure under the two controllers are almost the same, while the latter is more economic than the former.