scholarly journals Multipoint Wave Measurement in Tuned Liquid Damper Using Laser Doppler Vibrometer and Stepwise Rotating Galvanometer Scanner

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8211
Author(s):  
Yoon-Soo Shin ◽  
Junhee Kim
Keyword(s):  
Natural Frequency ◽  
Vibration Suppression ◽  
Laser Doppler Vibrometer ◽  
Laser Doppler ◽  
Liquid Level ◽  
Tuned Liquid Damper ◽  
Tuned Liquid Dampers ◽  
Liquid Dampers ◽  
Tuning Frequency ◽  
Galvanometer Scanner

Liquid dampers, such as tuned liquid dampers (TLDs), are employed to improve serviceability by reducing wind-affected building vibrations. In order to maximize the vibration suppression efficiency of the liquid damper, the tuning frequency of the liquid damper should match the natural frequency of the building. Experimental evaluation of the tuning frequency of a liquid damper performed in a factory prior to installation in a building is a critical task to ensure correct performance, and for this, multipoint measurement of the TLD is required. In this study, a novel liquid level measurement system combining Laser Doppler Vibrometer (LDV) and a stepwise rotating galvanometer scanner was developed to observe liquid sloshing in TLD. The proposed system can measure the liquid level at multiple points simultaneously with a single laser point. In the experimental phase, the liquid damper’s natural frequency and mode shape are experimentally evaluated utilizing the developed system. The performance of the proposed system was verified by comparison with the video sensing system.

scholarly journals An Electrical Wave Height Measurement at Spatial Multipoint Locations in Liquid Dampers for Structural Vibration Mitigation

2016 ◽  
Vol 2016 ◽  
pp. 1-9
Author(s):  
Junhee Kim ◽  
Seok-Jung Jang ◽  
Kyung-Won Min
Keyword(s):  
Electric Field ◽  
Natural Frequency ◽  
Vibration Suppression ◽  
Vertical Motion ◽  
Structural Vibration ◽  
Height Measurement ◽  
Tuned Liquid Dampers ◽  
Liquid Height ◽  
Liquid Dampers ◽  
Tuning Frequency

Liquid dampers such as tuned liquid column dampers and tuned liquid dampers have been adopted to ensure serviceability of a vibratory building subjected to wind. In order to maximize efficiency of the vibration suppression, tuning frequency of the liquid dampers is supposed to be set to the first natural frequency of the building. Therefore, experimental evaluation of the natural frequency of liquid dampers is a primal factory task prior to their installation at the building. In this study, a novel liquid height measurement system based on variable resistance in an electric field is developed for observation of vertical motion of the liquid dampers. The proposed system can simultaneously measure the liquid height of multipoint locations in the electric field. In the experimental phase, natural frequency of the liquid dampers is experimentally evaluated utilizing the developed system. The performance of the proposed system is verified by comparison with the capacitive type wavemeter.

Tuned Liquid Damper Experiment Using Shaking Table

2013 ◽  
Vol 421 ◽  
pp. 772-777 ◽  
Author(s):  
Ki Pyo You ◽  
Young Moon Kim ◽  
Jang Youl You
Keyword(s):  
Natural Frequency ◽  
Damping Ratio ◽  
Tall Buildings ◽  
Excitation Amplitude ◽  
Shaking Table ◽  
Tuned Liquid Damper ◽  
Tuned Liquid Dampers ◽  
Liquid Dampers ◽  
Water Tanks ◽  
Wind Induced Vibration

The present study examines the characteristics of rectangular and circular tuned liquid dampers, which control wind-induced vibration in tall buildings, according to the natural frequency. The tuned liquid dampers (TLD) were of frequencies: 0.44Hz, 0.55Hz, 0.64Hz and 0.73Hz. The tuning feature of TLD water tanks was better in circular water tanks than in rectangular water tanks. Excitation amplitude affected the damping ratio based on energy dissipation capacity. At low excitation (below 5mm) and low natural frequency (0.44Hz), circular water tanks were advantageous over rectangular water tanks. However, at high excitation (over 5mm) and high natural frequency (over 0.55Hz), rectangular water tanks were advantageous over circular water tanks.

Development of a novel tuned liquid damper with floating base for converting deep tanks into effective vibration control devices

2020 ◽  
pp. 136943322095353
Author(s):  
Tanmoy Konar ◽  
Aparna (Dey) Ghosh
Keyword(s):  
Vibration Control ◽  
Structural Response ◽  
Liquid Level ◽  
Water Level Fluctuations ◽  
Tuned Liquid Damper ◽  
Water Storage Tank ◽  
Tuned Liquid Dampers ◽  
Floating Base ◽  
Tank System ◽  
Liquid Dampers

Despite the proven effectiveness of tuned liquid dampers (TLDs), readily available liquid storage tanks are rarely utilized for vibration control of laterally-excited structures, as these are deep tanks with low inherent damping. Further, the fluctuation in liquid level in these tanks also causes variation in the fundamental sloshing frequency, leading to detuning. To overcome these problems, a novel TLD with floating base (TLD-FB) is proposed, in which a constant and shallow liquid level is maintained between the free liquid surface and the floating base. The liquid above the floating base acts as a conventional shallow TLD that always remains tuned to the structural frequency. The paper demonstrates how the TLD-FB can be incorporated into a water storage tank system on an example building without disturbing its functionality and achieves structural response reduction, despite water level fluctuations in the tanks.

Reduced Equivalent Static Wind Loads for Tall Buildings with Tuned Liquid Dampers

2012 ◽  
Vol 226-228 ◽  
pp. 1218-1227
Author(s):  
Andrew S. Ross ◽  
Ashraf A. El Damatty ◽  
Ayman M. El Ansary
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Tall Buildings ◽  
Wind Loading ◽  
Tuned Liquid Damper ◽  
Dynamic Component ◽  
Tuned Liquid Dampers ◽  
Liquid Dampers ◽  
Equivalent Static Wind Load ◽  
Auxiliary Device

The tuned liquid damper (TLD) is a proven and an increasingly popular auxiliary device for mitigating the dynamic effects induced by wind loading on tall buildings. As buildings become taller, lighter, and more flexible, there is a greater contribution from the dynamic component. The most reliable tool for assessing the dynamic component is wind tunnel testing. A boundary layer wind tunnel is capable of accurately calculating an equivalent static wind load (ESWL) acting on a building. The current study investigates the reduction in the ESWL of a lateral-torsional coupled building with a TLD system installed. The building is sensitive to torsion in the first two vibration modes. The current investigation uses three unique multi-modal TLD systems designed specifically for a lateral-torsional coupled building. The building ESWL is evaluated with the TLD systems using measurements from tests conducted at the Boundary Layer Wind Tunnel Laboratory at Western University.

Autoparametric Resonances of Elastic Structures Coupled With Two Sloshing Modes in a Square Liquid Tank

2011 ◽  
Author(s):  
Takashi Ikeda ◽  
Masaki Takashima ◽  
Yuji Harata
Keyword(s):  
Vibration Suppression ◽  
Equations Of Motion ◽  
Harmonic Balance Method ◽  
Liquid Level ◽  
Tuned Liquid Damper ◽  
Response Curves ◽  
Small Deviations ◽  
Sloshing Mode ◽  
Linear Damping ◽  
Good Agreement

Nonlinear vibrations of an elastic structure coupled with liquid sloshing in a square tank subjected to vertical sinusoidal excitation are investigated. Previous studies examined the vibrations of a structure coupled with only one sloshing mode in a rectangular tank. However, square tanks are expected to work more efficiently as a vibration suppression device (Tuned Liquid Damper, TLD) because two sloshing modes, (1,0) and (0,1) modes, simultaneously appear when the internal resonance ratio 2:1:1 is satisfied. In reality, it is impossible to build a perfectly square tank. Therefore, a nearly square liquid tank is also considered when the tuning condition is slightly deviated. In the theoretical analysis, the fluid in the tank is assumed to be perfect. The modal equations of motion for seven sloshing modes are derived using Galerkin’s method, considering the nonlinear terms. The linear damping terms are then incorporated into the modal equations to consider the damping effect of sloshing. The frequency response curves are determined using van der Pol’s method (based on the harmonic balance method). From these response curves, the influences of the liquid level, the aspect ratio of the tank cross section, and the deviation of the tuning condition are investigated. For a square tank it is found that (1,0) and (0,1) modes are nonlinearly coupled. When the liquid level is high, there are three patterns for sloshing: (I) both (1,0) and (0,1) sloshing modes appear at identical amplitudes; (II) these two modes appear at different amplitudes; and (III) either (1,0) or (0,1) mode appears. Compared with the performance of a rectangular TLD, a square TLD works more efficiently when the liquid level is low. Small deviations of the tuning condition may cause amplitude modulated motion to appear. Bifurcation sets are also calculated to illustrate the influence of the system parameters on the performance of the TLD. Experiments were also conducted in order to confirm the validity of the theoretical results. These results were in good agreement with the experimental data.

Experimental Test and Numerical Analysis of a Structure Equipped with a Multi-Tuned Liquid Damper Subjected to Dynamic Loading

2020 ◽  
Vol 20 (07) ◽  
pp. 2050075
Author(s):  
Bui Pham Duc Tuong ◽  
Phan Duc Huynh
Keyword(s):  
Shaking Table ◽  
Tuned Liquid Damper ◽  
Lumped Mass ◽  
Tuned Liquid Dampers ◽  
Lumped Mass Method ◽  
Dynamic Loadings ◽  
Coupling Equations ◽  
Liquid Dampers ◽  
Volume Method ◽  
Simplified Calculation

Tuned liquid dampers (TLDs) have many advantages in controlling building vibrations, among which multi-tuned liquid dampers (MTLDs) appear to have better stability and effectiveness. However, the tank wall was assumed to be rigid in the past by ignoring the fluid-structure interaction (FSI) at the interface, resulting in simplified calculation for the design of the TLDs. Moreover, the fluid in the tank was considered to be separate from the structure. This paper presents two numerical methods to control the responses of the frame under the dynamic loadings: (1) the lumped mass method for quickly designing the TLDs, and (2) the finite volume method/finite element method (FVM/FEM) for analyzing the fluid and solid domains of the TLDs in a single computational 3D model. In addition, the multi-field interaction between the structure-fluid-tank walls is considered by solving the coupling equations at the interfaces. A steel frame is fitted with an MTLD and tested experimentally on a shaking table to investigate its dynamic response. Numerical results are verified with the experimental ones, which show good agreement.

Vibration Control by Active Tuned Liquid Damper Using Magnetic Fluid

1997 ◽  
Author(s):  
Masato Abé ◽  
Yozo Fujino ◽  
Yasuyuki Sano
Keyword(s):  
Magnetic Field ◽  
Vibration Control ◽  
Magnetic Fluid ◽  
Model Building ◽  
Vibration Suppression ◽  
Tuned Liquid Damper ◽  
Base Shear ◽  
Suppression Effect ◽  
Tuned Liquid Dampers ◽  
Dynamic Magnetic Field

Abstract To enhance the performance of tuned liquid dampers (TLD), active TLD which contains magnetic fluid activated by electromagnet is proposed. At the first half of the paper, characteristics of sloshing motion of magnetic fluid subject to dynamic magnetic field is experimentally studied. Sloshing motion and base shear force are found to be effectively controlled by magnetic force. Then, a rule-based control law is constructed and applied to the vibration control of a model building. Vibration suppression effect of passive TLD is improved by applying appropriately scheduled dynamic magnetic field.

Linearized sloshing model for 2D tuned liquid dampers with modified bottom geometries

2014 ◽  
Vol 41 (2) ◽  
pp. 106-117 ◽  
Author(s):  
J.S. Love ◽  
M.J. Tait
Keyword(s):  
Mechanical Properties ◽  
Closed Form ◽  
Cost Savings ◽  
Mode Shapes ◽  
Tuned Liquid Damper ◽  
Flat Bottom ◽  
Tuned Liquid Dampers ◽  
Proposed Model ◽  
Sloshing Mode ◽  
Liquid Dampers

This study presents a new model for predicting the response of a two-dimensional tuned liquid damper (TLD) tank with a variable fluid depth. A simple finite element method is presented, which is used to calculate the sloshing mode shapes. From the mode shapes, the equivalent mechanical properties of the sloshing fluid are estimated. Three tanks (flat-bottom, triangular-bottom, and circular-bottom), which have closed-form expressions for their equivalent mechanical properties are used to evaluate the model. The proposed model is in agreement with the closed-form expressions. Subsequently, a parametric study is conducted on tanks with a chamfered-bottom, boxed-bottom, and ramped-bottom to assess how their properties change as the shape of the tank bottom is altered. The model provides TLD designers with greater flexibility when selecting a tank shape. Moreover, the model could be used to optimize the shape of a TLD tank to maximize its performance for a given liquid mass, allowing construction cost savings to be realized.

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