Experimental Study on Active Structural Control under Seismic Excitations with Different Source Distance

As buildings and bridges become more flexible, seismic-induced damage to these structures increases, and active mass damper (AMD) are widely applied for structural vibration control in the last three decades. Near-field, middle-field and far-field seismic excitations possess distinctly different dynamic characteristics, while relevant experimental studies on AMD control performance under such diverse ground motions remain insufficient. In this paper, a mathematical model of a three-story scaled steel frame equipped with a servomotor driven AMD is established. The liner quadratic regulator (LQR) control algorithm combined with a Kalman filter is employed for structural full-state estimation, and shaking table tests are carried out to explore the AMD control performance under three categories of seismic excitations with different source distances. The results show that the AMD control system achieves prominent vibration reduction, especially on the top floor. It effectively suppresses the first two modal responses of the structure, and presents the optimal control effect under near-field earthquakes. Nevertheless, restricted by installation deviation of the AMD device, the system cannot suppress the third-order modal response and even yields slight modal amplification, which deserves attention in practical application. This study verifies the applicability of servomotor driven AMD for seismic vibration control under different source distance ground motions.