The effect of tuned mass dampers and liquid dampers on cross-wind response of tall/slender structures

An investigation is made of the possible application of tuned liquid column dampers (TLCD) and tuned liquid column/mass dampers (TLCMD) in reducing the cross-wind response of wind-sensitive structures. The structure is modelled as a lumped mass multi-degree-freedom system taking into account both bending and shear. The cross-wind wake excitation is modelled as a stochastic process which is stationary in time and non-homogeneous in space. A random vibration analysis utilising transfer matrix formulation is carried out to obtain response statistics. The nonlinear damping term in the fundamental equation of the tuned liquid damper is treated by an equivalent linearization technique. Numerical examples show that tuned liquid dampers, which have significant practical advantages, can achieve the same motion reduction level as the traditional tuned mass dampers if the parameters of the liquid dampers are properly selected. However, excessive liquid motion in a tuned liquid column/mass damper may reduce the effectiveness of this damper and therefore a careful selection of the frequency tuning ratios of the damper is necessary.