Damping enhancement of liquid column vibration absorbers for structural control

Vibration control studies have shown that the Liquid Column Vibration Absorber (LCVA) has the potential to reduce vibrations of a structure subjected to unwanted excitations such as wind and earthquake. One drawback however, as realised through both numerical and experimental work, is that the use of the LCVA, although producing sufficient response reduction, has a tendency to cause re-excitation of the structure during the free vibration phase. Such a phenomenon has been shown to be caused by the inability of the LCVA to rapidly dissipate energy from the contained fluid. In order to overcome the re-excitation phenomenon the fluid motion needs to be damped to a greater extent, particularly when the structure comes to rest. One such method of increasing fluid damping is to incorporate orifice plates within the flow. The orifice plates increase the damping of the fluid and hence reduce re-excitation. Although the use of an orifice plate reduces the re-excitation, and sensitivity to mistuning, studies indicate that it occurs at the expense of structural response reduction.