Design of coupled tuned liquid column gas dampers for multi-mode reduction in vibrating structures

Tuned liquid column gas dampers (TLCGD) show excellent energy and vibration absorbing capabilities appropriate for earthquake engineering. The objective of this work is to introduce a new concept of coupled tuned liquid column gas dampers which allow an extended field of applications. In the proposed configuration, several absorbers are connected in a spatial chain generating a multi-degree of freedom damper system which can be tuned to a selected number of structural modes. Because all absorbers vibrate at different natural frequencies simultaneously, the proposed design represents an improvement over conventional TLCGD which can only be tuned to a single structural mode. Another benefit of multi-mode tuning is the significant increase in active liquid mass compared to other damping devices. For a most effective vibration reduction, a numerical tuning process in state space will deliver the free system natural frequency and damping ratio of all absorbers. The capabilities of the new damping device are demonstrated on a simple laboratory structure that is investigated numerically and experimentally. The results illustrate the excellent energy dissipating properties of the proposed setup and emphasize the adequacy of coupled TLGCD for base-isolated structures. A notable benefit of such types of dampers lies in their lack of moving mechanical parts, their cheap and easy implementation into civil engineering structures and low maintenance costs. Possible modifications with respect to natural frequency and even of the damping properties can be performed with little additional expenses, and the additional weight due to the liquid mass may be used as a possible reservoir, e.g., for fire fighting. Apart from that, they exhibit a performance that is comparable to tuned mass dampers.