Vibration control by multiple tuned liquid dampers (MTLDs)

The multiple tuned liquid dampers (MTLDs), which consist of a number of TLDs whose first natural frequencies of sloshing are distributed over a certain range around the natural frequency of a structure are studied. The simulations on the liquid motion in the MTLDs as well as the MTLDs-structure interaction are carried out by using a shallow water-wave theory. Then, two types of experiments, a forced-excitation experiment and an MTLDs-structure interaction experiment are conducted. The experiments and the simulation studies show that the MTLDs are efficient in the small amplitude range than the conventional TLDs, which have a single natural sloshing frequency, while the MTLDs efficiency is more or less the same level to that of the conventional TLDs in large amplitude range because of the damping nonlinearity of liquid motion. It is also shown that the control efficiency is not degraded, even though there is some offset in the tuning. This is the most significant point in actual engineering application. Finally, the application of the MTLDs to a high-rise building is presented as an example.