Hierarchical model-based control of semi-active tuned liquid column dampers with variable geometry and liquid volume

Vibration control for high-rise structures is more important as buildings become more lightweight and slender and thus have low inherent damping. For this problem, the application of tuned liquid column dampers (TLCD)s is an effective approach, as they achieve high damping forces while consuming low amounts of energy. The damping coefficient and natural frequency of TLCDs can be adjusted semi-actively by modifying the damper's geometry. As shown by previous studies, this approach increases the control performance of the damper and allows a larger application field. To reduce maintenance and the amount of energy required to operate the mechanism to adjust the damper's natural frequency, its actuation rate is constrained in this work. However, to control the TLCD's natural frequency, the existing approach is extended by additionally varying the liquid volume of the damper, which also effects the natural frequency. A hierarchical model-based control framework is proposed, which explicitly accounts for the nonlinear system dynamics of the coupled system consisting of a multi-storey structure with a semi-active TLCD. For the controller validation, a frequency response analysis is conducted on a 20-storey benchmark structure, which is equipped with a semi-active TLCD. The study is carried out in simulation and the results are compared to passive vibration control. A significant improvement in the reduction of structural vibrations over the relevant spectrum of excitation frequencies of up to 48 % is shown with the proposed hierarchical control.