The properties of tuned liquid dampers using a TMD analogy

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.

Journal of Wind Engineering and Industrial Aerodynamics, 1998

Rectangular tuned liquid dampers were investigated through shaking table tests and numerical modeling for large amplitude excitation. The results confirm earlier work undertaken for small amplitude excitation and considerably contribute to the body of knowledge describing tank behavior under large amplitude excitation. The random choice method of solving the fully nonlinear shallow-water-wave equations captures the underlying physical phenomenon adequately, including wave breaking, for most of the frequency range of interest. The tank behaves as a hardening spring system due to the liquid sloshing motion, and this trend is enhanced as excitation amplitude increases.

EPJ Web of Conferences, 2017

In this study shaking table tests which are applied on 3-Storey reduced shear frame models with TLD's subjected to harmonic loadings are presented. Firstly, free vibration experiments are conducted on the structure and 1 st free vibration frequency of the structure is determined. The structure is shaken under harmonic loading at a frequency equal to 1 st frequency of the structure which provides the resonance condition. Displacements and accelerations are measured at storey levels of the structure. A container in a rectangular prism shape is manufactured as a TLD model. Liquid is poured in the container and the same experiments are repeated at different liquid heights. The effect of TLD application on the structural models considering displacement and acceleration of the structure are investigated. In addition the effect of TLD application and its allocation at different storey levels are calculated experimentally. As a result of the conducted experiments, most convenient TLD models considering both displacement and acceleration behavior are determined. It is observed that all the damping models cause significant levels of reduction in seismic behavior of the structure under harmonic loading.

Engineering Structures, 1998

of Experimental studies have been conducted to investigate the feasibility of using active control of the tuned liquid damper for reducing the vibration of large civil structures. The results indicate that a simple mechanism can be designed to actively control the tuning of the system by adjusting the length of the liquid tank with rotatable baffles driven by stepping motors. The tank can be permanently installed and no powerful actuators would be required to regulate its motion. As a result, the system can be built inexpensively and can be tested frequently to ensure its reliability. A control strategy based on detection of frequency content and two-state control is simple and can be easily implemented in a microprocessor. Preliminary results of the damper model identification are provided, allowing computer simulations and the design of advanced control strategies for fine tuning of the liquid damper in future studies. The performance of this novel damper is verified by computer simulations and experiments using a physical model.

IRJET, 2022

The goal of this study is to examine the Tuned Liquid Damper (TLD) and Column Tuned Liquid Damper (CTLD), which are based on the movement of liquid in a rigid tank to change a structure's dynamic properties and lessen vibration energy during seismic excitation. A three-storey structure was created for this purpose and put through vibration tests. TLD and CTLD is install at top floor separately for different frequencies. A TLD and CTLD, is a device that employs water restrained in a container that is usually placed on top of a building to limit the displacement of the system when it is subjected to excitation. On a scaled model of the structure with TLD and CTLD, several experimental observations are made to assess their operation when subjected to seismic excitation. Using controlled uniaxial shake table testing, a rectangular-shaped TLD and CTLD with varying mass ratios are evaluated over various frequencies. Based on the structure's response reduction, TLD and CTLD effectiveness are assessed. The experiment's sensor, an accelerometer, measures the structure's acceleration in the presence and absence of a TLD and a CTLD while it is subjected to vibrations.

In this paper, the liquid damper (TLD) and mass damper (TMD) are used to minimize the structural retort due to moving action. Several experimental sets are measured on a model of structure TLD and TMD systems to check their efficiencies under vocal excitation. Rectangular shapes of TLD with altered type of liquid deepness ratios are checked and various frequency ratios are measured. The experimental revision was approved by expending shake table apparatus. The various values are measured using accelerometers and LVDT sensors. Trendy situation of TMD the toughness and restraining are remain constant for experimental study. From this study, it is established that for TLD, as water deepness raises it leads to minimum amplitude. The huge controller of vibration is noticed under resonant condition by using liquid damper. The outcomes show that TMD can decrease the extreme displacement of assemblies below harmonic motions.