Toshihiro Wakahara

Effectiveness of tuned liquid dampers under wind excitation

Abstract Full-scale measurements of the wind-induced responses of four buildings (two airport towers, an observatory tower and a highrise hotel) were conducted to prove the efficiency of tuned liquid dampers (TLDs). The damping ratios of the buildings with and without TLD were evaluated by both the run-down test technique and the random decrement technique. The wind-induced responses of the buildings were measured before and after installation of TLDs. The exceedance frequency of the response over the human perception thresholds was also examined. The results obtained in this study demonstrate that the TLDs could significantly improve the serviceability of the buildings.

Suppression of wind-induced vibration of a tall building using Tuned Liquid Damper

Abstract An optimum TLD design of a tall building required for comfort and serviceability was studied in this paper. In designing an optimum TLD, some design parameters which affected the TLD performance were investigated, and a new simulation method was developed to predict the effect of the TLD on vibration suppression of a tall building. From numerical simulations by using the proposed method, the TLD designed in this study effectively reduced the wind-induced response for improved serviceability.

A non-linear numerical model of the tuned liquid damper

The Tuned Liquid Damper (TLD) is modelled numerically as an equivalent tuned mass damper with non-linear stiffness and damping. These parameters are derived from extensive experimental results described in References 1 and 2. This Non-linear Stiffness and Damping (NSD) model captures the behaviour of the TLD system adequately under a variety of loading conditions. In particular, the NSD model incorporates the stiffness hardening property of the TLD under large amplitude excitation.

Wind-induced vibration of tower and practical applications of tuned sloshing damper

Abstract Wind-induced vibrations of two actual tall towers were reduced to about half upon installation of newly developed Tuned Sloshing Damper, which utilizes liquid motion in circular container. Vibrations at Nagasaki Airport Tower (height 42 m) and Yokohama Marine Tower (height 101 m) were measured during gusty day, before and after installation of damper. The reduced vibration levels after installation were in the range acceptable from the view point of comfort and serviceability. To further estimate the effects of Tuned Sloshing Damper, the dynamic force frequency response function of STD was experimentally determined. Using this frequency response function, numerical simulation on gust responses was conducted. The results indicate that the amplitude level is reduced to about half and this qualitatively agrees well with observation in the Yokohama Marine Tower.