• Title, Summary, Keyword: Tuned Sloshing Damper

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Design Parameter of a New Type Bi-directional Damper Using a Tuned Liquid Column Damper and a Tuned Sloshing Damper (TLCD와 TSD를 이용한 새로운 형태의 양방향 감쇠기 설계변수)

  • Min, Kyung-Won
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.8
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    • pp.850-856
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    • 2009
  • A new type bi-directional damper using a tuned liquid column damper(TLCD) and a tuned sloshing damper(TSD) is introduced in this study. Two dampers are usually needed to reduce wind-induced responses of tall buildings since they are along and across wind ones. The proposed damper has the advantage of controlling both responses with one damper. One of objectives of this study is to derive analytical dynamics to investigate coupled effects due to TLCD and TSD. Another objective is to address the effect of coupled control force due to TLCD and TSD on the dynamic characteristic of the damper based on analytical dynamics. Shaking table test is undertaken to experimentally grasp dynamic characteristics of the damper under white noise excitation. Its dynamic characteristic is expressed by the transfer function from the shaking table acceleration to the control force generated from the damper. Finally, its design parameters are identified based on the coupled dynamics, which include the mass ratio of horizontal liquid column to total liquid for a TLCD, the participation factor of the fundamental liquid sloshing for a TSD and damping ratio for both cases.

Bi-directional response control of a building using one TLD (1 개의 TLD 를 이용한 건물의 양방향 진동제어)

  • Min, Kyung-Won;Lee, Sung-Kyung;Park, Eun-Churn
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.119-124
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    • 2009
  • This paper proposes a tuned liquid column sloshing damper(TLCSD) and presents experimental results to evaluate its control performance. The proposed damper acts as a tuned liquid column damper(TLCD) and a tuned liquid damper(TLD), respectively, in both principal axes of building structures. Shaking table test was performed to grasp its dynamic characteristics. Testing results showed that under inclined incident excitations, a TLCSD used in this study have dynamic characteristics coupled by both TLCD and TLD.

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The Vibration Performance Experiment of Tuned Liquid Damper and Tuned Liquid Column Damper

  • Kim Young-Moon;You Ki-Pyo;Cho Ji-Eun;Hong Dong-Pyo
    • Journal of Mechanical Science and Technology
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    • v.20 no.6
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    • pp.795-805
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    • 2006
  • Tuned Liquid damper and Tuned Liquid Column are kind of passive mechanical damper which relies on the sloshing of liquid in a rigid tank for suppressing structural vibrations. TLD and TLCD are attributable to several potential advantages - low costs ; easy to install in existing structures : effective even for small-amplitude vibrations. In this paper, the shaking table experiments were conducted to investigate the characteristics of water sloshing motion in TLD (rectangular, circular) and TLCD. The parameter obtained from the experiments were wave height, base shear force and energy dissipation. The shaking table experiments show that the liquid sloshing relies on amplitude of shaking table and frequency of tank. The TLCD was more effective control vibration than TLD.

Testing of tuned liquid damper with screens and development of equivalent TMD model

  • Tait, M.J.;El Damatty, A.A.;Isyumov, N.
    • Wind and Structures
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    • v.7 no.4
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    • pp.215-234
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    • 2004
  • The tuned liquid damper (TLD) is increasingly being used as an economical and effective vibration absorber. It consists of a water tank having the fundamental sloshing fluid frequency tuned to the natural frequency of the structure. In order to perform efficiently, the TLD must possess a certain amount of inherent damping. This can be achieved by placing screens inside the tank. The current study experimentally investigates the behaviour of a TLD equipped with damping screens. A series of shake table tests are conducted in order to assess the effect of the screens on the free surface motion, the base shear forces and the amount of energy dissipated. The variation of these parameters with the level of excitation is also studied. Finally, an amplitude dependent equivalent tuned mass damper (TMD), representing the TLD, is determined based on the experimental results. The dynamic characteristics of this equivalent TMD, in terms of mass, stiffness and damping parameters are determined by energy equivalence. The above parameters are expressed in terms of the base excitation amplitude. The parameters are compared to those obtained using linear small amplitude wave theory. The validity of this nonlinear model is examined in the companion paper.

The efficiency and robustness of a uni-directional tuned liquid damper and modelling with an equivalent TMD

  • Tait, M.J.;Isyumov, N.;El Damatty, A.A.
    • Wind and Structures
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    • v.7 no.4
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    • pp.235-250
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    • 2004
  • The current study reports the results of an experimental program conducted on a structure fitted with a liquid damper (TLD) and subjected to harmonic excitation. Screens were placed inside the TLD to achieve the required inherent damping. In the first part of the study, reduced scale models of the building-TLD systems were tested under two levels of excitation. The efficiency of the damper was assessed by evaluating the effective damping provided to the structure and comparing it to the optimum effective damping value, provided by a linear tuned mass damper (TMD). An extensive parametric study was then conducted for one of the three models by varying both the excitation amplitude and the tuning ratio, defined as the ratio of the TLD sloshing frequency to the natural frequency of the structure. The effectiveness and robustness of a TLD with screens were assessed. Results indicate that the TLD can be tuned to achieve a robust performance and that its efficiency is not significantly affected by the level of excitation. Finally, the equivalent amplitude dependent TMD model, developed in the companion paper is validated using the system test results.

Numerical simulation of tuned liquid tank- structure systems through σ-transformation based fluid-structure coupled solver

  • Eswaran, M.;Reddy, G.R.
    • Wind and Structures
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    • v.23 no.5
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    • pp.421-447
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    • 2016
  • Wind-induced and earthquake-induced excitations on tall structures can be effectively controlled by Tuned Liquid Damper (TLD). This work presents a numerical simulation procedure to study the performance of tuned liquid tank- structure system through ${\sigma}$-transformation based fluid-structure coupled solver. For this, a 'C' based computational code is developed. Structural equations are coupled with fluid equations in order to achieve the transfer of sloshing forces to structure for damping. Structural equations are solved by fourth order Runge-Kutta method while fluid equations are solved using finite difference based sigma transformed algorithm. Code is validated with previously published results. The minimum displacement of structure is observed when the resonance condition of the coupled system is satisfied through proper tuning of TLD. Since real-time excitations are random in nature, the performance study of TLD under random excitation is also carried out in which the Bretschneider spectrum is used to generate the random input wave.

Numerical Investigation on Surge Motion of a Rectangular Floating Body due to Inner Sloshing Phenomena (내부 슬로싱 현상에 따른 사각상자 형태의 부유체 서지 거동에 대한 수치적 고찰)

  • Ha, Minho;Cheong, Cheolung
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.7
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    • pp.662-668
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    • 2013
  • In this paper, possibility of controlling motion of a floating structure using a tuned liquid damper (TLD) is numerically investigated. A TLD is a tank partially filled with liquid. Sloshing motion of liquid inside a tank is known to suppress movement of the tank subject to external excitations at specific frequency. The effects of sloshing phenomena inside a rectangular floating body on its surge motion are investigated by varying external excitation frequency. First, a grid-refinement study is carried out to ensure validity of grid independent numerical solutions using present numerical techniques. Then, surge motion of the floating body subjected to external wave is simulated for five different excitation frequencies of which the center frequency equals to the natural frequency of internal liquid sloshing. The normalized amplitudes of surge motion of the target floating body are compared according to the excitation frequency, for the cases with and without water inside the floating body. It is shown that the motion of the floating body can be minimized by matching the sloshing natural frequency to the excitation frequency.

Sloshing characteristics of an annular cylindrical tuned liquid damper for spar-type floating offshore wind turbine

  • Jeon, S.H.;Seo, M.W.;Cho, Y.U.;Park, W.G.;Jeong, W.B.
    • Structural Engineering and Mechanics
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    • v.47 no.3
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    • pp.331-343
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    • 2013
  • The natural sloshing frequencies of annular cylindrical TLD are parametrically investigated by experiment, aiming at the exploration of its successful use for suppressing the structural vibration of spar-type floating wind turbine subject to multidirectional wind, wave and current excitations. Five prototypes of annular cylindrical TLD are defined according to the inner and outer radii of acryl container, and eight different liquid fill heights are experimented for each TLD prototype. The apparent masses near the first and second natural sloshing frequencies are parametrically investigated by measuring the apparent mass of interior liquid sloshing to the acceleration excitation. It is observed from the parametric experiments that the first natural sloshing frequency shows the remarkable change with respect to the liquid fill height for each TLD model with different container dimensions. On the other hand, the second natural sloshing frequency is not sensitive to the liquid fill height but to the gap size, for all the TLD models, convincing that the annular cylindrical sloshing damper can effectively suppress the wave- and wind-induced tilting motion of the spar-type floating wind turbine.

Numerical study of sway motion of a rectangular floating body with inner sloshing phenomena (내부 슬로싱 현상을 이용한 사각상자 형태의 부유체 Sway 거동 모사에 대한 수치적 고찰)

  • Ha, Minho;Cheong, Cheolung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.161-165
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    • 2013
  • In this paper, possibility of controlling motion of a floating structure using a tuned liquid damper (TLD) is numerically investigated. A TLD is a tank partially filled with liquid. Sloshing phenomena of liquid inside a tank can suppress movement of the tank subject to external excitations at specific frequency. The effects of sloshing phenomena inside a rectangular floating body on its sway motion are investigated by varying excitation frequency. First, a grid-refinement study is carried out to ensure validity of grid independent numerical solutions using present numerical techniques. Then, sway motion of the floating body subjected to wave with five different frequencies are simulated. The normalized amplitudes of sway motion of the target floating body are compared over the frequency, for cases with and without water inside the floating body. It is shown that the motion of the floating body can be minimized by matching the sloshing natural frequency to excitation frequency.

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Performance Test of a Tuned Liquid Mass Damper installed in a Real-Scaled Structure (실물크기 구조물에 설치된 동조액체질량감쇠기의 성능실험)

  • Heo, Jae-Sung;Park, Eun-Churn;Lee, Sang-Hyun;Lee, Sung-Kyung;Min, Kyung-Won;Kim, Hong-Jin;Jo, Ji-Seong;Cho, Bong-Ho;Joo, Seok-Jun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.449-457
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    • 2008
  • In this paper, a tuned liquid1) mass damper(TLMD) was proposed and experimentally investigated on its control performance, which can control bi-axial responses of building structures by using only one device. The proposed TLMD controls the structural response in a specific one direction by using a liquid sloshing of TLCD. Also, the TLMD reduces the response of structures in the other orthogonal direction by behaving as a TMD that uses mass of the container itself and liquid within container of TLCD installed on linear motion guides. Force-vibration tests on a real-sized structure installed with the TLMD were performed to verify its independent behavior in two orthogonal directions. Test results showed that the responses of a structure were considerably reduced by using the proposed TLMD and its usefulness for structural control in two orthogonal directions.

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