Semi-active omnidirectional liquid column vibration absorber with rapid frequency adjustment capability

Abstract

This paper explores the semi-active omnidirectional liquid column vibration absorber, a unique tuned liquid column damper consisting of multiple circularly distributed columns for the control of vibrations in all lateral directions. Each column features actuator-controlled cells that can trap liquid and adjust column cross-sections, facilitating a rapid shift in natural frequency during operation. Unlike previous semi-active tuned liquid column dampers, this design can modulate its natural frequency without altering the total liquid mass and eliminate the need for overpressure or additional springs. Validation is conducted on a full-scale omnidirectional prototype. However, the trapped liquid mass plays a crucial role in determining the damper’s optimal tuning parameters and affects the resulting restoring force, emphasizing its significance in the design process. This research introduces a comprehensive mathematical model of the absorber, accompanied by a control algorithm, and proposes a corresponding design approach. Moreover, a shape function informed by experimental damping is developed to address complexities arising from geometry and cell arrangements. The focus of the study is the lateral vibration control of high-rise civil engineering structures. Numerical and experimental analyses demonstrate the superior adaptability of the absorber to fluctuating structural properties, marking a significant improvement over its passive counterpart in various loading scenarios.