Synthesize identification and control for smart structures with time‐varying parameters under unknown earthquake excitation

Abstract

The synthesis of structural identification with vibration control is cost-effective and beneficial for developing smart building structures. In the past several decades, techniques have been put forward for the combination of structural identification and vibration control. However, it is still a challenging task to synthesize identification and vibration control of time-varying structures under unknown earthquake excitation. First, structural dynamic responses collected by a structural health monitoring (SHM) system are absolute responses under unknown earthquake excitation, so existing identification approaches for unknown external excitations are not applicable for this situation. Moreover, it is essential to have an efficient algorithm for accurately tracking the various scenarios of time-varying structural physical parameters with inexpensive computation to ensure the real-time performance requested by structural vibration control. In this paper, an algorithm is put forward to tackle this challenging problem. It is proposed to treat structural time-varying effect as “virtual unknown inputs” to the corresponding time-invariant structure. A generalized extended Kalman filtering with unknown input (GEKF-UI) is proposed to circumvent the limitations of the existing EKF-UI approaches. The proposed GEKF-UI can simultaneously identify structural system, unknown earthquake excitation, and the “virtual unknown inputs” using only partially measured structural absolute responses. Then, the identified structural state is synthesized in real time with the instantaneous optimal control strategy for optimal semiactive control provided by magnetorheological dampers. Therefore, the proposed algorithm can track various structural time-varying with much less computation, which is more suitable for synthesis with structural control compared with other existing approaches. Some numerical cases of synthesizing identification and vibration control of various type time-varying structures under unknown earthquake motion are adopted to investigate the feasibilities of the proposed algorithm.