Numerical Study of Slat Screen Pattern Effect on Design Parameters of Tuned Liquid Dampers

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Morteza Marivani ◽  
M. S. Hamed
Keyword(s):  
Fluid Flow ◽  
Numerical Investigation ◽  
Natural Frequency ◽  
Linear Theory ◽  
Tall Buildings ◽  
Design Parameters ◽  
Damping Factor ◽  
Tuned Liquid Dampers ◽  
Solidity Ratio ◽  
Liquid Dampers

Tuned liquid dampers (TLDs) are considered economical and effective dynamic vibration absorbers. They are increasingly being used to mitigate the dynamic resonant response of tall buildings and it is often designed to reduce the structure's acceleration at a serviceability limit state. Slat screens can increase the inherent damping factor of TLDs. They have been used as a common flow damping device in TLDs because of the simplicity of using them and also the ability to control their effects on the performance of a TLD. Two slat screens with the same solidity ratio and different patterns could have different effects on the TLD's performance. Many former numerical researches used the potential and linear theory as a base to describe the fluid flow behavior inside the TLD. The applicability of the linearized flow models was for the condition of the low amplitude of excitations. Under large excitation events such as high return period wind storms or earthquakes, the assumptions of linear theory are no longer valid. Moreover, in the linearized model, screens were modeled as a hydraulic resistance point as a function of the screen solidity ratio without the ability to consider the effect of screen pattern. In the present study, a numerical algorithm has been developed which can handle both the small and large amplitude of excitations. In this algorithm, the fluid flow through the screen is fully resolved and it can take into account the effect of the screen pattern on the TLD's performance. The major focus of this paper is to use this developed algorithm and conduct a numerical investigation to study the effects of the slat screen pattern on the inherent damping and natural frequency of the TLD, as the design parameters of the TLD. In this numerical investigation a selected TLD outfitted by different slat screens and interacted with the structure is exposed by both harmonic and random external excitations. The numerical results have been validated against experimental work. The effect of slat screen pattern on the damping effect and natural frequency of a TLD has been presented. Also in this study, two new parameters termed as slat ratio (SR) and effective solidity ratio (Seff) are presented to imply the physical significance of screen pattern.

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.

Theoretical and Experimental Studies on Reduction for Multi-Modal Seismic Responses of High-Rise Structures by Tuned Liquid Dampers

2004 ◽  
Vol 10 (7) ◽  
pp. 1041-1056 ◽  
Author(s):  
Hong-Nan Li ◽  
Ying Jia ◽  
Su-Yan Wang
Keyword(s):  
Passive Control ◽  
Equations Of Motion ◽  
Experimental Studies ◽  
Tall Buildings ◽  
Shaking Table ◽  
Earthquake Ground Motion ◽  
Seismic Responses ◽  
High Rise ◽  
Tuned Liquid Dampers ◽  
Liquid Dampers

This paper focuses on the use of multiple tuned liquid dampers (TLDs) as passive control devices to reduce the multi-modal responses of tall buildings and high-rise structures to earthquake ground motion excitation. A model of a three-story building with one and two TLDs was installed on a shaking-table. The system was subjected to three earthquake time histories. Then, the mechanical models and the equations of motion for the systems of tall buildings and high-rise structures with TLDs are established. Here, the solution of the dynamic liquid pressure is based on the method of the volume of fluid and the seismic responses are obtained by use of the state equation. The comparisons show that theoretical results are generally in good agreement with experiments. It is observed that the approach presented in this paper has proved to be quite effective both in the numerical example and in the seismic simulating tests.

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.

Experimental Verifications on Seismic Response Control of Tall Structures by Multiple Tuned Liquid Dampers

2004 ◽  
Author(s):  
Hong-Nan Li ◽  
Ying Jia ◽  
Su-Yan Wang
Keyword(s):  
Passive Control ◽  
Equations Of Motion ◽  
Tall Buildings ◽  
State Equation ◽  
Shaking Table ◽  
Earthquake Ground Motion ◽  
High Rise ◽  
Tuned Liquid Dampers ◽  
Tall Structures ◽  
Liquid Dampers

The focus of this paper is on the use of multiple Tuned Liquid Dampers (TLDs) as passive control devices to reduce the multi-modal responses of tall buildings and high-rise structures to earthquake ground motion excitation. A model of a 3-story building with one and two TLDs was installed on a shaking-table. The system was subjected to three earthquake time histories. Then the mechanical models and the equations of motion for the systems of tall buildings and high-rise structures with TLDs are established. Here, the solution of the dynamic liquid pressure is based on the method of the Volume of Fluid and the seismic responses are obtained by use of the state equation. The comparisons show that theoretical results are generally in good agreement with experiments. It is observed that the approach presented in this paper proved to be quite effective both in the numerical example and in the seismic simulating tests.

Surge Response Control of FPSO Using Multiple Tuned Liquid Dampers: A Study on Effect of Multiple Frequencies in TLD

2019 ◽  
Author(s):  
Saravanan Gurusamy ◽  
Deepak Kumar
Keyword(s):  
Crude Oil ◽  
Natural Frequency ◽  
Flexible Structures ◽  
Deep Ocean ◽  
Wave Loads ◽  
Natural Period ◽  
Response Control ◽  
Tuned Liquid Dampers ◽  
Oil Storage ◽  
Liquid Dampers

Abstract Industries rely mostly on off-shore resources to fulfill the increase in demand for oil and gas. In general, for oil extraction and various other refinery processes, fixed or floating structures are being utilized. Floating Production Storage and Offloading (FPSO) system is one of the floating systems which have advantage of storing the crude oil and, if required, it can be easily moved to other places. Also, in deep Ocean where sub-sea pipeline infrastructures are often not possible and so the FPSOs give alternate option of storing and processing the crude oil. Being moored-systems, FPSOs are very flexible structures having high surge natural period and hence they may undergo larger surge displacement. Excessive displacement may cause damage for the riser system also it may affect the workability under extreme sea condition. Therefore, there is a need for investigating the issues of safety, efficiency and response control of FPSO systems under different sea-state conditions. Ocean wave loads on FPSO causes dynamic interaction between FPSO vessel and liquid in the oil storage containers. The liquid motion in containers disturbs the dynamics of the vessel significantly. Hence, it is essential to study the surge response control of FPSO in detail. An easy way to control the response is to use the existing cargo containers of FPSO as passive damping devices. If the natural frequency of liquid oscillation is tuned to the natural frequency of FPSO, these cargo tanks can act as Multiple Tuned Liquid Dampers (MTLDs). In case of simple linear model, Tuned liquid damper (TLD) can be idealized as a Single Degree of Freedom (SDOF) system, namely Tuned Mass Damper (TMD). The present study attempts to model a TLD using three different TMD systems to account the effects of shallow water sloshing.

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 Analytical Solution of Sloshing in a Cylindrical Tank with an Elastic Cover

Mathematics ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 1070 ◽  
Author(s):  
Mohammad Yaghoub Abdollahzadeh Jamalabadi
Keyword(s):  
Natural Frequency ◽  
Fluid Motion ◽  
Cover Plate ◽  
Parameter Study ◽  
Seismic Safety ◽  
Fluid Structure ◽  
Tuned Liquid Dampers ◽  
Aspect Ratios ◽  
Liquid Dampers ◽  
Elasticity Number

Coupled fluid-structure is significant in many aspects of engineering applications such as aerospace fuel tanks, the seismic safety of storage tanks and tuned liquid dampers. Numerical investigation of the effects of thin plate cover over a cylindrical rigid fuel tank filled by an inviscid, irrotational, and incompressible fluid is investigated. Governing equations of fluid motion coupled by plate vibration are solved analytically. A parameter study on the natural frequency of coupled fluid-structure interaction is performed. The results show the non-dimensional natural frequency of coupled fluid-structure is a function of mass ratio, plate elasticity number and aspect ratio. This function is derived numerically for high aspect ratios which in companion with a semi-analytical could be used in the engineering design of liquid tanks with a cover plate.

EARTHQUAKE VIBRATION CONTROL USING SLOSHING LIQUID DAMPERS IN BUILDING STRUCTURES

2012 ◽  
Vol 06 (01) ◽  
pp. 1250002 ◽  
Author(s):  
AVIK SAMANTA ◽  
PRADIPTA BANERJI
Keyword(s):  
Passive Control ◽  
Broad Band ◽  
Tall Buildings ◽  
Degree Of Freedom ◽  
Effective Control ◽  
Building Structures ◽  
High Rise ◽  
Tuned Liquid Dampers ◽  
Damper Design ◽  
Liquid Dampers

Sloshing liquid dampers (SLDs), popularly known as tuned liquid dampers, are used as passive control devices for reducing structural vibrations resulting from wind and earthquake excitations in tall buildings and high-rise structures. Available research studies on these dampers mostly deal with single-degree-of-freedom (SDOF) structures although tall buildings and high-rise structures are generally multi-degree-of-freedom (MDOF) structures. In the present investigation, effectiveness of these SLDs has been studied for MDOF building structures. Five-storied shear buildings have been considered as representative of MDOF structures. It is shown that the liquid sloshing is the most important design parameter, rather than tuning of the fundamental sloshing frequency to the structure frequency, for the liquid damper to be effective. Furthermore, the liquid damper design for multistory buildings is different from that for SDOF structures, where not only the optimal tuning ratio of the liquid damper is different, but multiple dampers located at critical locations are required for effective control of floor accelerations. Finally, it is illustrated that SLDs, if appropriately designed, can be very effective in reducing overall force, floor acceleration, and deformation responses of MDOF building structures for broad-band earthquake type base excitations.

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