Performance Of Tuned Liquid Damper Research Articles

Numerical investigation of structural models equipped with tuned liquid damper

Tuned liquid dampers (TLDs) are introduced in structural systems to suppress vibration of the structure due to dynamic actions. Using a grid-based Finite Volume Method-Finite Element Method (FVM/FEM), efficiency of TLDs of cylindrical and rectangular geometries was evaluated by performing a two-way Fluid-Structure Interaction (FSI) analysis. The nonlinear sloshing response of fluid was simulated by employing a three-dimensional Navier–Stokes equation as the governing equation and occurrence of wave breaking was accounted by using Volume of Fluid (VOF) method for free surface tracking. Utilizing the developed numerical model, a series of three-dimensional transient analysis were conducted on a structure with and without TLDs aiming to investigate effect of base excitation amplitude. The result show that maximum performance of TLDs at resonance is obtained when the forcing ratio is limited to 0.1, and for this case, both cylindrical and rectangular TLDs displayed comparable efficiency. Effect of excitation frequency fe was also investigated under a wide range of the forcing ratio showing that as fe increases, the natural frequency of coupled TLD-structural system approaches the natural frequency of un-damped structural system.

Shaking table substructure test of tuned liquid damper for controlling earthquake response of structure

For precisely disclosing the seismic performance of tuned liquid damper (TLD) vibration control structures, the shaking table substructure test (STST) method is presented and experimentally validated, and the parametric effects on the reduction efficiency of TLD are further investigated by using the STST method in this paper. Firstly, one optimal design method of TLD for high-rise structures is presented. Secondly, the STST based on three variable control method (TVCM) for the TLD vibration control structures is presented. Thirdly, the effectiveness and robustness of the STST for TLD vibration control structures are validated by a series of tests on one three-story-frame structure with a rectangular TLD. Finally, the parametric effects on the reduction efficiency of TLD, in terms of mass ratio and liquid depth, are investigated using the STST method. Experimental results show that the displacement and acceleration responses of the STST match well with that of the traditional shaking table tests under El Centro (NS, 1940) and Taft earthquake wave record excitations, which indicates the effectiveness and the robustness of the STST based on TVCM for TLD vibration control structures. It is also shown from the experimental results that the best mass ratio and liquid depth are 4% and 40 mm, respectively, which are consistent with the optimal designs of TLD. Moreover, the control performance of TLD is not only related to its parameters but also related to the spectral characteristics of ground motion excitations.

Robustness evaluation of optimum tuned liquid dampers for uncertain variable loading of structures

This study focuses on the performance analysis of optimum tuned liquid dampers (TLDs) under the different live loads of three different structure models, designed as both single and multi-story, under earthquake excitations. For this purpose, single, ten, and forty story structure models have been created and tuned liquid damping devices that contain liquids of different densities and viscosities such as acetone, mercury, and seawater are placed on the structure. For the analysis conducted under earthquake excitations, optimum damping device parameters were previously obtained with the Adaptive Harmony Search Algorithm (AHS), and minimizing the movement of the structure was aimed. The effect of the damping device on the control performance was investigated under increasing and decreasing live loads for the uncertain mass of the structure because of variable actions. When the results are examined, it has been determined that the increase in the story number of the structure will less affect the displacement reduction performance of TLDs for the structure under uncertain variable loading.

Wave vibration control of jacket platform by tuned liquid dampers

The studies on the applications of tuned mass and liquid column dampers for wave vibration control of offshore structures are notable. Though, the same is not the case for tuned liquid dampers (TLD). However, TLDs are a natural candidate for vibration control of flexible structure by utilizing the sloshing motion of fluid. The present study explores the effectiveness of TLD to mitigate the wave induced vibration effect of offshore jacket platform. In doing so, the jacket platform is modelled considering soil pile interaction effect and the TLD is represented by a spring mass system with due consideration to sloshing energy of water. The performance of TLD to control the wave induced vibration is studied for regular wave load, obtained by Stokes' fifth order theory and also for random wave load, generated by using the Pierson–Moskowitz wave spectrum. The dynamic response analyses are carried out without and with TLD for varying mass ratio, depth ratio and position of placement to study the effect of different parameters on the performance of TLD system. The results of numerical study in general show that TLD is potential for wave vibration mitigation of offshore jacket platform.

A metaheuristic‐based optimum tuning approach for tuned liquid dampers for structures

SummaryThis study focuses on the optimization of tuned liquid dampers (TLDs) by using metaheuristic methods using a natural phenomenon as inspiration. Unlike tuned mass dampers (TMDs), TLDs consist of two parts of bodies that contain the passive liquid that is stationary and the active part of the liquid that involves in sloshing. To optimize the amount of optimum active and passive liquids by finding the best dimensional properties of the liquid tank, a two‐degree‐of‐freedom (DOF) model was used as TLD in the dynamic analysis used in the optimization that aims to reduce the maximum displacement of the structure under earthquake excitations. For this purpose, water, oil, and glycerin liquids were selected for TLD. TLD parameters were optimized with the help of Jaya algorithm, flower pollination algorithm (FPA), harmony search (HS) algorithm, and teaching–learning‐based optimization (TLBO). Total acceleration and maximum displacement were evaluated after optimization. The performance of TLD under earthquake excitations has been also compared with TMDs. According to the results, the optimized TLD has a better performance than TMD, and Jaya algorithm has a slightly better performance than the other algorithms.

Numerical investigation of the response of structures equipped with a limited freeboard tuned liquid damper

The tuned liquid damper (TLD) uses liquid sloshing in a tank to suppress unwanted wind-induced vibration of a flexible structure. The tank interior height is traditionally selected such that sloshing waves do not impact the tank ceiling by providing sufficient freeboard between the free surface and the tank ceiling. To optimize a TLD for a space with height constraints, it is possible to design the tank to have intentionally limited freeboard. This study numerically investigates the response of a structure equipped with a limited freeboard TLD using an incompressible smoothed particle hydrodynamics (SPH) model. Seven excitation force intensities are studied at nine different freeboard heights. The SPH results are used to assess the performance of the limited freeboard TLD. In general, limiting freeboard is found to reduce the effectiveness of the TLD. When the fundamental sloshing mode is not constrained by the tank ceiling, the TLD performs comparably well to its unlimited freeboard counterpart. If the fundamental sloshing mode is constrained by the tank ceiling, the motion reduction performance of the TLD is affected. The equivalent damping ratio of the fundamental sloshing mode is evaluated from the SPH results. An equivalent linear mechanical model that can be used for preliminary feasibility studies of the system with limited freeboard is presented. Additional TLD damping due to ceiling impact proportional to the reduction in wave height is introduced. The mechanical model is found to reasonably capture the structure response when compared to the SPH results.

A numerical study of tuned liquid damper based on incompressible SPH method combined with TMD analogy

Tuned liquid dampers (TLDs) are economical dynamic vibration absorbers which are increasingly being used for structural response control. Nevertheless, a thorough understanding of the sloshing behavior inside the TLD is essential for efficient design. In this paper, a truly incompressible smoothed particle hydrodynamics (ISPH) method is employed to circumvent the difficulties regarding the simulation of fully nonlinear sloshing motion induced by large amplitude excitations. The behavior of the TLD with damping screens is studied numerically over a wide range of excitation frequencies and amplitudes. It is found through comparison with the existing experimental data that the ISPH model is a powerful tool for accurate predictions of the TLD behavior. The amplitude-dependent properties of an equivalent tuned mass damper (TMD) model, which is capable of reproducing the energy dissipation characteristics of the TLD, are derived from the simulations results. Good agreement between the numerical and experimental results is indicative of the equivalent model’s ability to predict the response of structure–TLD systems, suggesting that the ISPH model can properly simulate the TLD behavior. The effect of screen placement on the performance of structure–TLD systems is also investigated. Findings reveal that improved performance of TLD can be realized under high amplitude excitations by placing the damping screens in the locations corresponding to the higher sloshing modes.

Evaluate pressure drop of slat screen in an oscillating fluid in a tuned liquid damper

Tuned liquid dampers (TLDs) are considered economical and effective dynamic vibration absorbers. Using of slat screens in TLDs can increase the inherent damping factor of TLDs. In many former numerical efforts, screens were modeled as a hydraulic resistance point as a function of the screen solidity ratio without the ability to consider the effect of the screen pattern. Clear understanding of the pressure drop across the slat screens, as the major factor for controlling the inherent damping of TLDs, enrolls a great effect on improving the performance of TLDs. Two slat screens with the same solidity ratio and different patterns could cause the different levels of the pressure drop and so inherent damping in TLDs. In the developed algorithm, the fluid flow through the screen is fully resolved and the effect of the screen pattern on the TLD's performance is taken into account. The numerical results of the developed algorithm have been validated against experimental work. Using this algorithm, a new pressure drop model for the slat screens has been developed considering the effects of the screen pattern through introducing two new concepts called the effective solidity ratio (Seff) and the slat ratio (SR) which they can imply the physical significance of screen pattern.

Tuned liquid dampers for multi-storey structure: numerical simulation using a partitioned FSI algorithm and experimental validation

Wind-induced and earthquake-induced vibrations of structures such as super-tall towers and bridges can be efficaciously controlled by tuned liquid dampers (TLDs). This work presents a numerical simulation procedure to study the performance of TLDs–structure system through sigma (\( \sigma \))-transformation-based fluid–structure coupled solver. For this, a ‘C’-based computational code has been developed. The structural equations, which are coupled with the fluid equations in order to achieve the transfer of sloshing forces to structure for damping, are solved by the fourth-order Runge–Kutta method, while the fluid equations are solved using finite-difference-based sigma-transformed algorithm. Different iterative and error schemes are used to optimize the code for larger convergence rate and higher accuracy. For validation, a few experiments are conducted with a three-storey structure using TLDs arrangement. The present numerical results of response of TLD-installed structures match well with the experimental results. The minimum displacement of structure is observed when the resonance condition of the coupled system is achieved through proper tuning of TLDs. Since real-time excitations are random in nature, the performance study of TLDs under random excitation has also been carried out in which the Bretschneider spectrum is used to generate the random input wave.

Evaluation of Sloped Bottom Tuned Liquid Damper for Reduction of Seismic Response of Tall Buildings

Due to migration of people to urban area, high land costs and use of light weight materials modern buildings tend to be taller, lighter and flexible. These buildings possess low damping. This increases the possibility of failure during earthquake ground motion and also affect the serviceability during wind vibrations. Out of many available techniques today, to reduce the response of structure under dynamic loading, Tuned Liquid Damper (TLD) is a recent technique to mitigate seismic response. However TLD has been used to mitigate the wind induced structural vibrations. Flat bottom TLD gives energy back to the structure after event of dynamic loading and it is termed as beating. Beating affects the performance of TLD. Study attempts to analyze the effectiveness of sloped bottom TLD for reducing seismic vibrations of structure. Concept of equivalent flat bottom LD has been used to analyze sloped bottom TLD. Finite element method (EM) is used to model the structure and the liquid in the TLD. MATLAB code is developed to study the response of structure, the liquid sloshing in the tank and the coupled fluid-structure interaction. A ten storey two bay RC frame is analyzed for few inputs of ground motion. A sinusoidal ground motion corresponding to resonance condition with fundamental frequency of frame is analyzed. In the analysis the inherent damping of structure is not considered. Observations from the study shows that sloped bottom TLD uses less amount of liquid than flat bottom TLD. Also observed that efficiency of sloped bottom TLD can be improved if it is properly tuned.

Real-time hybrid simulation of the size effect of tuned liquid dampers

The use of tuned liquid dampers (TLDs) is an effective passive control technique to suppress structural vibration under wind and seismic loads. This paper investigates the size effect of TLDs on control efficiency. Given the advantages of real-time hybrid simulation, two issues affecting the control performance of TLD are addressed: (a) the geometric size and (b) the experimental model scale. A series of real-time hybrid simulations is performed, in which TLD devices with various sizes (including full-scale and small-scale) are experimentally modeled as physical substructures; the controlled structures are numerically simulated as numerical substructures. Results demonstrate that TLD performance is size dependent; a shallow liquid in TLD with lower relative liquid depth may be more efficient for both peak and root-mean-square response control. Scaled TLD models that are usually used in conventional shaking table tests generally overestimate the control performance of prototype TLD devices, indicating that full-scale TLD experiments should be pursued to ensure proper performance evaluation.

Seismic Performance of SDF Systems with Tuned Liquid Damper Subjected to Ground Motions

Tuned Liquid Dampers(TLD) are energy dissipation devices that have been proposed to control the dynamics response of structure. The TLD has been shown to effectively control the wind response of structures. However, controlling responses of structures with TLD under seismic loads are not fully investigated. The objective of this study is to evaluate the seismic performance of single degree of freedom(SDF) with TLDs having various tuning and mass raitos. For this purpose, analytical studies are conducted. Different soil conditions are considered in this study. As a result, performance of TLD, appeared diffrently depending on the natural period, damping ratio of the structure. Also TLD tuning ratio appeared differently.동조액체감쇠기(TLD)는 에너지 소산장치로써 구조물의 동적응답을 제어하기 위해 개발되었다. TLD는 풍하중에 의한 구조물의 응답을 제어에 매우 효과적임을 보여줬다. 그러나 TLD가 설치된 구조물의 지진응답의 제어에 대해서는 충분한 연구가 이뤄지지 않았다. 이 연구의 목적은 TLD가 설치된 구조물에 여러 동조비와 질량비를 대입하여 지진에 대한 TLD의 성능을 도출하는 것이다. 이러한 목적을 위해, 수치해석 연구가 실시되며, 다른 토양 조건 또한 고려되었다. 그 결과 지진하중에 대한 TLD의 성능은 구조물의 고유주기, 감쇠비에 따라 다르게 나타났다. 또한 TLD의 동조비 다르게 나타남을 알 수 있었다.

Real-time hybrid simulation of multi-story structures installed with tuned liquid damper

As a low cost and maintenance energy-absorbing device, tuned liquid damper (TLD) is being widely used to suppress structural vibration. In this paper, the real-time hybrid simulation (RTHS) is employed to investigate the performance of TLD for controlling seismic responses of actual multi-story structures, where the TLD is experimentally modeled as physical substructure and the multi-story structure is numerically simulated as numerical substructure. Taking advantage of RTHS technique, a methodology for achieving full-scale TLD experiments is developed through suitable similarity design; a new interaction force measurement method and a new dual explicit algorithm are embedded into RTHS system to enhance simulation capability. First, the seismic response of a two-story structure installed with TLD is analyzed by applying RTHS. Correspondingly, the pure shaking table test is performed to assess the accuracy of the RTHS. Then, the effectiveness of TLD for structures with various numbers of floors and different structural properties is tested through RTHS by varying the simulation model of the numerical substructure. Finally, the effects of mass ratio and structural damping ratio on a given TLD-structure system are investigated. Copyright © 2015 John Wiley & Sons, Ltd.

Experimental investigation of utilizing TLD with baffles in a scaled down 5-story benchmark building

A tuned liquid damper (TLD) is a special type of auxiliary damping device, which relies on the sloshing of a liquid (water) in a container to counteract the forces acting on the structure. Damping in the TLD is introduced as a result of liquid sloshing and wave breaking. A conventional TLD is generally tuned to the main frequency of the building and is less efficient in other frequencies. Because of this limitation, the TLD is usually used to control the structural response of structures, which could be simulated as a SDOF structure, and mostly due to wind forces. In this paper a new kind of tuned liquid damper with some installed rotatable baffles is studied experimentally. The main idea behind installing such baffles is to compensate the effects of probable mistuning of the TLD and also it is an effort toward making the TLD more controllable, i.e. a semi-active damper. Response of a five story benchmark building was utilized to investigate the contributions of these baffles on efficiency of tuned liquid damper under dynamic and earthquake excitations. By observing the performance of TLD with baffles, the study investigates the influence of a number of parameters, include the following: baffles angles, frequency ratio, mass ratio and especially the effects of probable mistuning with changing the depth of water and orientation of baffles. The damping ratios of the building for a range of baffles angles were evaluated using logarithmic decrement technique. The results that are obtained in this paper show that the displacement and acceleration responses of the structure under the free vibration test utilizing the baffles reduced up to 2.5% and 3.9%, respectively, when compared with the case where no baffles are employed. Also the dynamic magnification factor under harmonic excitation reduced up to 2.7% proportional to baffles angles. Damping of the structure equipped with this type of TLD increased in a range of 3.93–6.38% when compared to the case of using no damper. The displacement and acceleration responses of the building under scaled down earthquakes also decreased up to 24.07% and 27.24%, respectively, with some of the best control results occurring before full closure of baffles.

Modeling of Tuned Liquid Damper With Submerged Nets

An analytical model for describing the effectiveness of tuned liquid damper (TLD) with submerged nets for suppressing horizontal vibration of structures is proposed. Dissipation energy due to the liquid motion under sinusoidal excitation is calculated based on nonlinear shallow water wave theory. In particular, the effects of hydraulic resistance produced by nets installed in a tank on the performance of TLDs are examined. The results of dissipation energy theoretically obtained are confirmed by experiments. To show the effectiveness of the proposed analytical model for TLD-structure interaction problems, the case in which TLD with nets is installed on top of a pylon of a cable-stayed bridge is described and the calculated results are compared with the actual experimental data. In the calculation, it is shown that the optimal damping factor, as is the case for tuned mass dampers (TMD), can be produced by the nets, and the effectiveness of TLD with nets are demonstrated.