The properties of tuned liquid dampers using a TMD analogy

Doboku Gakkai Ronbunshu, 1988

A new kind of damper, Tuned Liquid Damper (TLD) relying on motion of shallow liquid in a rigid cylinder, is experimentally studied. Prototype-sized circular containers with diameters 40 cm and 60 cm and partially filled with water, are attached to a single-degreeof-freedom structural model with natural period of 2 sec. The damper effect is measured in terms of the increase in the logarithmic rate of decrement of free oscillation of the main structure. The structural displacements range from 8 cm down to 0.25 cm. It is seen that, for large damping effect at small amplitude of structural vibration, it is necessary to tune the fundamental sloshing period of the liquid to the natural period of structure; hence the name Tuned Liquid Damper. Breaking of surface waves, which is dependent on structural vibration amplitude, appears to be a major mechanism of energy dissipation in the range of displacements considered. Also investigated are the effects of: ratio of liquid frequency to structure frequency; liquid viscosity; container bottom roughness; container roof height; ratio of liquid mass to structure mass; and container diameter.

International Journal of Advanced Structural Engineering, 2013

This paper investigates the performance of unidirectional tuned liquid damper (TLD) that relies upon the motion of shallow liquid in a rigid tank for changing the dynamic characteristics of a structure and dissipating its vibration energy under harmonic excitation. A series of experimental tests are conducted on a scaled model of structuretuned liquid damper systems to evaluate their performance under harmonic excitation. One rectangular and one square TLD with various water depth ratios are examined over different frequency ratios, and time histories of accelerations are measured by precisely controlled shaking table tests. The behaviour of TLD is also studied by changing the orientation of the rectangular TLD subjected to the given range of harmonic excitation frequencies. The effectiveness of TLD is evaluated based on the response reduction of the structure. From the study, it is found that for each TLD, there exists an optimum water depth that corresponds to the minimum response amplitude, and the maximum control of vibration is obtained under resonance condition with the attachment of TLD.

Simulation Modelling Practice and …, 2003

In recent years, tuned liquid dampers (TLD) have proved a successful control strategy for reducing structural vibrations. The present study focuses on the frustum-conical TLD as an alternative to the traditional cylindrical tank. If compared to the cylindrical reservoir, the cone-shaped TLD allows calibrating its natural frequency through varying liquid depth, which makes it suitable for a semi-active implementation, and attains the same level of performance with a fewer mass, at least for small fluid oscillations. A linear model is presented which can interpret TLDÕs behaviour for small excitations. For larger amplitudes, strong nonlinearities occur and the linear model is no longer predictive. Consequently, for a frustum-cone TLD subjected to harmonic excitations, a tuned mass damper (TMD) analogy is established where TMD parameters vary with the excitation amplitude.

Doboku Gakkai Ronbunshu, 1989

The interaction between rectangular Tuned Liquid Damper (TLD) and structure is investigated both experimentally and theoretically. A TLD-structure interaction model is developed where the dynamic interaction force is theoretically evaluated by applying the nonlinear shallow water wave theory. Good agreements are found between the experimental results and the theoretical simulation within the range where no breaking of wave occurs inside the TLD. Effectiveness of TLD is demonstrated for sinusoidal forced excitation. An example of TLD design procedure is also given using the TLD-structure interaction model.

Simulations done on single degree of freedom structures (SDOF) connected rigidly to a tuned liquid damper (TLD) and under various excitation shows that TLD can reduce structural response to these excitation considerably if designed perfectly. TLD is a rectangular (or circular) rigid tank which is partly filled with water and its sloshing frequency is tuned to regular frequency of structure. As increasing the base excitation level, TLD is more efficient, which is because of more energy dissipation via sloshing and wave breaking. Comparing with TMD, the TLD has some limitations. In this paper the limitation of TLD tank dimensions is investigated and it is shown that because of difficulties in providing desired mass ratio, utilizing this device in structures with natural frequencies over that 1.5-2.0 is extremely limited. Also it is shown that utilizing this device for structures with natural frequencies less than 1 is suitable and justifiable.

International Journal of Engineering, 2022

To endure strong ground motions in large earthquakes, structures need to be equipped with tools to damp the huge amounts of energy induced by these excitations. In conventional buildings, seismic energy is often handled by a combination of rigidity-ductility measures and energy dissipation solutions. Since these buildings often have very low damping capability, the amount of energy dissipated within their elastic behavior phase tends to be negligible. Passive dampers are vibration control systems that can serve as valuable tools for controlling strong forces and reducing the probability of structural failure under seismic loads. In Tuned Liquid Dampers (TLDs), energy is dissipated by exploiting the behavior and characteristics of the liquid contained in the damper's tank. When the structure is subjected to external stimuli, the force transferred to the damper starts moving the liquid that lies stationary in the damper's tank, getting dissipated in the process. There are various classes of TLDs with different tank shapes, aspect ratios, and mechanisms of action, each with its properties and features. Another cause of energy dissipation in TLDs, in addition to the viscosity of the liquid, is the base shear force that is applied to the damper's intersection with the main structure with a phase difference relative to the external excitation, because of the difference between hydrostatic forces exerted on the walls at the two ends of the tank. Therefore, the level of liquid interaction with the damper's walls is also a determinant of the damping of external forces and thus the seismic response of the structure. The study investigated a new type of TLD with a double-walled cylindrical tank. To examine the effect of this TLD on the seismic response, a series of models were built with different liquid heights in the tank's inner and outer walls and subjected to several seismic excitations on a shaking table. The results showed that using this type of damper reduced the seismic response of the structures. Also, the reduction in seismic response was found to change significantly with the amount of liquid in the damper.

This paper investigates the performance of a new type of cost-efficient damper for mitigating wind and earthquake induced vibrations in tall buildings. Tuned Liquid Damper (TLD) is a type of Tuned Mass Damper (TMD) where the mass is replaced by a liquid (usually water). A TLD relies upon the motion of shallow liquid in a rigid tank for changing the dynamic characteristics of a structure and dissipating its vibration energy under harmonic excitation. The effectiveness of TLD is evaluated based on the response reduction of the structure which is a two-storied steel building frame. Various parameters that influence the performance of TLD are also studied.

Simulations conducted on single degree of freedom structures (SDOFs) connected rigidly to a tuned liquid damper (TLD) under various excitations show that TLD can reduce structural response to these excitations considerably if properly designed. TLD is a rectangular (or circular) rigid tank partly filled with water where its sloshing frequency is tuned to natural frequency of structure. As increasing the base excitation level, TLD is more efficient, which is because of more energy dissipation via sloshing and wave breaking. A conventional TLD is generally tuned to a single frequency. Because of this limitation, the TLD usually is used to control the structural response of semi-SDOF structures. Overcoming this drawback, some standing baffles are suggested to be installed inside the TLD which can rotate around their vertical axis. The numerical simulations show that these baffles can change the damping ratios, frequency of sloshing and sloshing forces especially in baffles orientation between 30 to 50 degrees. This can be utilized to make the TLD, variably tuned liquid damper.

Journal of Engineering Mechanics-asce, 1992

A new kind of passive mechanical damper, tuned liquid damper (TLD). is studied that relies upon the motion of shallow liquid in a rigid tank for changing the dynamic characteristics of a structure and dissipating its vibration energy. A nonlinear model of two-dimensional liquid motion inside a rectangular TLD subjected to horizontal motion is developed on the basis of shallow-water wave theory, where the damping of the liquid motion is included semianalytically. Using the model, the response of a structure with TLD is also computed. The liquid motion inside the TLD under harmonic base excitation and, furthermore, the response of a single-degree-of-freedom structure with TLD, subjected to harmonic external force, are experimentally investigated. The agreement is good between the experiment and the prediction.

Doboku Gakkai Ronbunshu, 1989

Tuned Liquid Damper (TLD) utilizing the motion of shallow liquid for absorbing and dissipating the vibrational energy is studied with emphasis on liquid motion. A mathematical model based on the nonlinear shallow water wave theory is presented to describe the liquid motion in a rectangular tank. Liquid damping is evaluated semianalytically and is included in the formulation. Mechanical properties of TLD are also experimentally investigated using the shaking table. It is found that the liquid motion in TLD is strongly nonlinear and reveals a hardening-spring property even under small excitation. Good agreements between the simulation and the experimental results are shown when no breaking wave occurs. The model presented in this study is expected to serve as a tool for TLD design.