Multiple Tuned Liquid Dampers Research Articles

Investigation on the efficiency of deep liquid tanks in controlling dynamic response of high-rise buildings: A computational framework

High-rise buildings are subjected to large deflection when exposed to environmental loading due to cyclones or earthquakes. Different methodologies are available to control such excessive deflections. The present work explores the utilization of liquid storage service tanks placed at the roof of the high-rise buildings in the form of passive damping devices in controlling unwanted vibration. These deep liquid tanks (DLTs) have a higher depth ratio than the conventional tuned liquid dampers (TLDs). A 10-storeyed reinforced concrete (RC) building model, square shaped, symmetric in plan, is considered for the numerical assessment. A multiple TLD (MTLD) system is designed to control the roof displacement of the building. This MTLD system is then replaced by a single DLT, which provides slightly better control efficiency under resonant harmonic loading. The system coupling facility of ANSYS Workbench provides fluid structure interaction (FSI) platform to solve structure-fluid coupled dynamics. ANSYS Transient Structural module is used to solve the structure part using the finite element analysis (FEA), whereas, ANSYS (FLUENT) for the fluid part using the computational fluid dynamics (CFD). The focus of the work is to develop a practical framework to demonstrate the efficacy of such liquid storage tanks considering the FSI effect using coupled FEA-CFD analysis. The aim is to arrive at an appropriate damper efficiency considering the position and size of the DLT with different liquid filling level. The selected DLT, along with the position is replaced by distributed deep liquid tanks (DDLTs), conserving the overall mass of the damper (liquid). It is observed that the DDLT may not be an effective alternative to the single DLT device. In specific cases, properly designed DLTs can be recommended over MTLD system as effective damping devices for vibration mitigation purposes in high-rise buildings.

Numerical Study on Various Position of Multiple Water Tanks toward Earthquake on High-rise Building

Earthquake can cause many problems to the structures, which lead to building collapse and may takes humans life. One of the effort to reduce the structural response is by introduce the damping system to the buildings where the energy of the system is slowly reduced until the vibration of the system is totally eliminated and the system is brought to rest. Several techniques are available nowadays, however passive control system has advantage in term of cost especially in Malaysia where the earthquake is not the major threat like in Japan but it is good to tune existing water tank to became a passive damper where it is there went situation needed. The objective of the present paper is to analyse the practicality of implementing multiple water tank as passive Multiple Tuned Liquid Damper and finding the best position of water tanks, which would reduce peak response of the structure subjected to seismic forces using SAP2000. 15 multi-storey concrete structure attached with five water tanks with 3 different situation of water tanks location under consideration. In order to study the depth ratio parameter, the water level was varies for each situation such as ¼ tank for all water tanks, half tanks for all water tanks and ¾ tank for all water tanks. The results shows that Position 2 filled with ¾ water has highest significant reduction in term of structural displacement which is 12.6mm compare to other water tanks positions and water level.

Multiple TLDs on Motion Reduction Control of the Offshore Wind Turbines

This study explores the damping effects of tuned liquid dampers (TLDs) on a monopile offshore wind turbine (OWT). The fluid–solid coupling of ANSYS was used to simulate the damping effect of a TLD on the structures. The environmental conditions refer to the IEC-61400-3 and the Design Load Case (DLC) 1.2 for the annual average environmental conditions and DLC 6.2 for the 50-year regression period, and the extreme environmental conditions were used in the study. The turbulent wind field simulation was performed by TurbSim, and the load of wind waves on structures was generated by FAST, which were all developed by the NREL (National Renewable Energy Laboratory). In addition to wind and waves, the seismic force was also considered. The cylindrical TLD was located above the rotor nacelle assembly (RNA). A TLD has different damping effects when acting under wind, wave, and earthquake loads, respectively. The effect of the TLD regarding motion reduction on the OWT under coupled wind, wave, and seismic loads was studied. This study also designed a simple experiment to verify the correctness of the numerical simulation results. Fatigue analysis shows that multi-layer TLDs can extend the fatigue life (37%) of an OWT. In addition, under extreme environmental load conditions, multi-layer TLDs have a better vibration damping performance than single-layer TLDs. The study demonstrates that multi-layer TLDs can be considered as a vibration reduction damper for OWTs.

Shaking Table Test on Different Positions of Multiple Tuned Liquid Damper

Earthquake can cause many problems to the structures, which lead to buildings collapse and may takes humans life. It is a nature’s hazard that cannot be stop. One of the effort is by introducing the damping system to the buildings where the energy of the system is slowly reduced until the vibration of the system is totally eliminated and the system is brought to rest. Several techniques are available nowadays, however passive control system has advantage in term of cost compare to other systems. Multiple Tuned Liquid Damper (MTLD) is a passive system that traditionally made of several rigid tanks filled with water, usually placed on top of a building. The energy will dissipates through the sloshing and wave-breaking of the liquid once the earthquake strike the buildings. Shaking table tests are carried out on a two-bay, two-story steel frame with water tanks for different location. In this test, the displacement and acceleration for top and base are studied.

Optimal control of vibration by multiple tuned liquid dampers using Taguchi method

This paper investigates the multiple tuned liquid dampers (MTLD), which consist of a number of MTLD whose first natural frequencies of sloshing are distributed over a certain range around the natural frequency of a structure. The liquid motion in the MTLD as well as the MTLD-structure interaction are numerically simulated using a shallow water-wave theory. An optimal procedure based on Taguchi method is proposed to determine the optimum parameters of MTLD to suppress the vibration amplitude of the considered structure. A number of numerical tests are included to demonstrate and verify the effectiveness of the proposed procedure.

Optimal design of multiple annular tuned liquid dampers for seismic reduction of 1,100-kV composite bushing

It is of great significance to perform seismic mitigation for the 1,100-kV composite bushings because they are vulnerable to damage during earthquakes. In this paper, a new design process of multiple tuned liquid dampers (MTLDs), utilizing the displacement transfer function curves and the equivalent mechanical model of annular tuned liquid damper (ATLD), is proposed for seismic reduction of the 1,100-kV composite bushing. At first, the equivalent mechanical model of ATLD is derived based on the linear wave theory. The effects of the radius ratio and the liquid-filled depth ratio on the equivalent sloshing mass are discussed. The accuracy of the equivalent mechanical model is also verified by comparing the results with those from the Housner's model and the finite element model. And then, the transfer functions of the structure with MATLD attached are formulated in the frequency domain. The parameters, including the frequency ratio, the mass ratio, and the damping ratio, that influence the transfer function curves are also investigated. Based on these transfer function curves, the new design process of MATLD is presented. Combining with the equivalent mechanical model of ATLD, a dynamic analysis of the bushing equipped with MATLD in the dome is performed under the real earthquake records. It is concluded that the MATLD performs better than the ATLD and the bushing equipped with 5ATLD in the dome is the optimal design for seismic reduction.

An experimental study on response control of structures using multiple tuned liquid dampers under dynamic loading

In this paper, the performance of multiple tuned liquid damper (MTLD) has been investigated in mitigating the response of a structure under dynamic loading, i.e., harmonic excitation. For comparative study, the responses of single-tuned liquid damper (STLD) have also been considered. A set of experiments are conducted on a scaled model of steel-structure-STLD and MTLD systems to evaluate the performance of the respective TLD models under harmonic excitation. Several excitation frequency ratios (0.5–2.0) and depth ratios (0.05–0.30) are considered for this study. The effect of resonance as well as tuned condition (ωd/ωs = 1) on the structural response has also been noticed. The effectiveness of the STLD and MTLDs is evaluated based on the response reduction of the structure. It has been found that the structural responses of displacement and acceleration are reduced significantly due to the installation of STLD and MTLD to the structure, respectively. Therefore, from this experimental study, it can be concluded that a TLD can successfully mitigate the response of the structure, but MTLD is not significantly more effective than an STLD when the liquid sloshing in the TLD is large.

Development and Validation of Finite Element Structure-Tuned Liquid Damper System Models

Implementation of supplemental damping systems (e.g., the dynamic vibration absorbers (DVAs)) to mitigate excessive tall building vibrations induced by external dynamic loads (wind storms or earthquakes) has increased over the last several decades. A tuned liquid damper (TLD) is a specific type of the DVAs that consists of a rigid tank which is partially filled with a liquid, usually water. The sloshing liquid inside the tank provides inertia forces that counteract the forces acting on the structure, thus reducing the building motion. A single sway mode of vibration is usually targeted, however, for certain structures multiple modes may need to be suppressed. Moreover, the location of the TLD on the floor plate is important for certain modes, such as a torsionally dominate mode. In this paper, a three-dimensional (3D) finite element (FE) structure-TLD system model (3D-structure-TLD) is proposed where the TLDs can be positioned at any location on the structure allowing the most effective positions in reducing the structure's dynamic response to be determined. Therefore, the response of a 3D structure (tower, high-rise building, bridge, etc.) fitted with single or multiple TLD(s) and subjected to dynamic excitation can be predicted using the proposed FE model. For torsionally sensitive structure (eccentric/irregular structures), this type of 3D numerical analysis is highly recommended. Two nonlinear TLD models are employed to simulate the TLD and implemented in the FE model. The 3D-structure-TLD system model is validated for the cases of sinusoidal and random excitation forces using existing experimental test values. Results from the 3D-structure-TLD system model are found to be in excellent agreement with values obtained from experimental tests.

Multiple Tuned Liquid Dampers for Efficient and Robust Structural Control

AbstractIn traditional tuned liquid damper (TLD) installations, TLD tank(s) are tuned to a single optimal frequency as determined by well-known dynamic vibration absorber theory. A multiple tuned liquid damper (MTLD) is created when the sloshing frequencies are distributed over a range near the structural frequency. In this paper, an equivalent mechanical model for a structure–MTLD system is developed. A third-order nonlinear multimodal model is employed to assess nonlinear fluid affects and serve as independent model verification. To the authors’ knowledge, this is the first time the nonlinear energy dissipation associated with damping screens and the nonlinear coupling amongst sloshing modes has been considered for MTLD systems. MTLD systems consisting of one (traditional TLD), two, and three tanks are used to reduce the resonant response of a single degree of freedom structure. The MTLD provides structural control that is superior to a traditional TLD. The MTLD is less sensitive to the structural excit...

Use of TLD and MTLD for control of wind-induced vibration of tall buildings

Excessive acceleration experienced at the top floors in a building during wind storms affect the serviceability of the building with respect to occupant comfort and discomfort. Tuned liquid damper (TLD) and multiple tuned liquid damper (MTLD), which are passive control devices consisting of a rigid tank filled with liquid, are used to suppress vibration of structures. These TLD and MTLD offer several potential advantages-low costs, easy installation in existing structures and effectiveness even for small-amplitude vibrations. This study carries out a theoretical estimation of the most effective damping ratios that can be achieved by TLD and MTLD. Damping by TLD an MTLD reduced the frequency response of high-rise buildings by approximately 40% in urban and suburban areas.

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.