• Title, Summary, Keyword: viscoelastic

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Efficient Control of Tall Buildings with Viscoelastic Dampers (점탄성 감쇠기가 설치된 고층건물의 효율적인 진동제어)

  • 김상태
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.167-174
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    • 1997
  • Viscoelastic dampers have been successfully applied in building structures to reduce vibration by wind and earthquakes. It may be inefficient or be uneconomical that viscoelastic damper is installed at each story of building structures. Although the number of viscoelastic dampers is reduced, if viscoelastic dampers are installed at only suitable places in building structures, vibration would be controlled by efficiency. In this paper, responses of building structures according to the situation of viscoelastic dampers are compared. Then efficient and economical arrangements of viscoelastic dampers are proposed.

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Boundary Element Analysis of Strain Energy Release Rate G(t) for Cracked Viscoelastic Solids (균열이 있는 선형 점탄성체의 변형에너지 방출률 G(t)에 대한 경계요소 해석)

  • 박명규;이상순;서창민
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.12
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    • pp.2072-2078
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    • 2003
  • In this paper, the boundary element analysis of viscoelastic strain energy release rate G(t) for the cracked linear viscoelastic solids has been attempted. This study proposes the G(t) equation and the calculating method of G(t) by time-domain boundary element analysis for the viscoelastic solids. The G(t) is defined as the derivative of the viscoelastic potential energy II(t) with respect to crack length a. Two example problems are presented to show the applicability of the proposed method to the analysis of the cracked linear viscoelastic solids. Numerical results of example problems show the accuracy and effectiveness of the proposed method.

Application of the Laplace transformation for the analysis of viscoelastic composite laminates based on equivalent single-layer theories

  • Sy, Ngoc Nguyen;Lee, Jaehun;Cho, Maenghyo
    • International Journal of Aeronautical and Space Sciences
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    • v.13 no.4
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    • pp.458-467
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    • 2012
  • In this study, the linear viscoelastic response of a rectangular laminated plate is investigated. The viscoelastic properties, expressed by two basic spring-dashpot models, that is Kelvin and Maxwell models, is assumed in the range to investigate the influence of viscoelastic coefficients to mechanical behavior. In the present study, viscoelastic responses are performed for two popular equivalent single-layered theories, such as the first-order shear deformation theory (FSDT) and third-order shear deformation theory (TSDT). Compliance and relaxation modulus of time-dependent viscoelastic behavior are approximately determined by Prony series. The constitutive equation for linear viscoelastic material as the Boltzmann superposition integral equation is simplified by the convolution theorem of Laplace transformation to avoid direct time integration as well as to improve both accuracy and computational efficiency. The viscoelastic responses of composite laminates in the real time domain are obtained by applying the inverse Laplace transformation. The numerical results of viscoelastic phenomena such as creep, cyclic creep and recovery creep are presented.

Multi-dimensional seismic response control of offshore platform structures with viscoelastic dampers (II-Experimental study)

  • He, Xiao-Yu;Zhao, Tie-Wei;Li, Hong-Nan;Zhang, Jun
    • Structural Monitoring and Maintenance
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    • v.3 no.2
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    • pp.175-194
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    • 2016
  • Based on the change of traditional viscoelastic damper structure, a brand-new damper is designed to control simultaneously the translational vibration and the rotational vibration for platforms. Experimental study has been carried out on the mechanical properties of viscoelastic material and on its multi-dimensional seismic response control effect of viscoelastic damper. Three types of viscoelastic dampers with different shapes of viscoelastic material are designed to test the influence of excited frequency, strain amplitude and ambient temperature on the mechanical property parameters such as circular dissipation per unit, equivalent stiffness, loss factor and storage shear modulus. Then, shaking table tests are done on a group of single-storey platform systems containing one symmetric platform and three asymmetric platforms with different eccentric forms. Experimental results show that the simulation precision of the restoring force model is rather good for the shear deformation of viscoelastic damper and is also satisfied for the torsion deformation and combined deformations of viscoelastic damper. The shaking table tests have verified that the new-type viscoelastic damper is capable of mitigating the multi-dimensional seismic response of offshore platform.

Dynamic Characteristics of Full-Scale Viscoelastic Dampers (실물크기 점탄성 감쇠기의 동적 특성)

  • 민경원
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.367-374
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    • 1999
  • this paper focuses on the dynamic characteristics of full-scale viscoelastic dampers through the experimental study. Viscoelastic dampers which dissipate the response energy of a building under earthquake excitation make a role of increasing damping capacity of the building. Therefore it is important to recognize the damping behavior of viscoelastic dampers. Full-scale viscoelastic dampers are made of three types of rubbers for experimental test. The hysteretic behavior is obtained through the load-deformation experiment over the various loading frequencies and damper strains The experimental results show the good performance of viscoelastic dampers under earthquake excitations,

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Analysis of building frames with viscoelastic dampers under base excitation

  • Shukla, A.K.;Datta, T.K.
    • Structural Engineering and Mechanics
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    • v.11 no.1
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    • pp.71-87
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    • 2001
  • A frequency domain response analysis is presented for building frames passively controlled by viscoelastic dampers, under harmonic ground excitation. Three different models are used to represent the linear dynamic force-deformation characteristics of viscoelastic dampers namely, Kelvin model, Linear hysteretic model and Maxwell model. The frequency domain solution is obtained by (i) an iterative pseudo-force method, which uses undamped mode shapes and frequencies of the system, (ii) an approximate modal strain energy method, which uses an equivalent modal damping of the system in each mode of vibration, and (iii) an exact method which uses complex frequency response function of the system. The responses obtained by three different methods are compared for different combinations of viscoelastic dampers giving rise to both classically and non-classically damped cases. In addition, the effect of the modelling of viscoelastic dampers on the response is investigated for a certain frequency range of interest. The results of the study are useful in appropriate modelling of viscoelastic dampers and in understanding the implication of using modal analysis procedure for building frames which are passively controlled by viscoelastic dampers against base excitation.

Seismic study of buildings with viscoelastic dampers

  • Pong, W.S.;Tsai, C.S.
    • Structural Engineering and Mechanics
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    • v.3 no.6
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    • pp.569-581
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    • 1995
  • In this paper, the seismic behavior of a 10-story building equipped with viscoelastic dampers is analyzed. The effects of ambient temperature, the thickness, the total area, and the position of the viscoelastic dampers are studied. Results indicate that the energy-absorbing capacity of viscoelastic damper decreases with increasing the ambient temperature. The thickness and the total area of viscoelastic dampers also affect the seismic mitigation capacity. The thickness cannot be too small, which is not effective in vibration reduction, nor can it be too large, which not only increases the cost but also reduces the seismic resistance. The total area of viscoelastic dampers should be determined properly for optimum damper performance at the most economical design. The mounting position of viscoelastic dampers also influences the structure's seismic performance. Numerical results show that, if properly equipped, the VE dampers can reduce the structural response both floor displacement and story shear force and increase the overall level of damping in structures during earthquakes.

Dynamic Analysis of Building Structures with Viscoelastic Dampers (탄성감쇠를 가진 건축구조물의 동적해석)

  • 이동근
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.196-203
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    • 1998
  • Viscoelastic dampers have been successfully applied to building structures for reduction of vibration induced by wind or earthquakes. But accurate estimation of responses of building structures with viscoelastic dampers is very difficult, because the properties of viscoelastic damper is dependent on temperature and frequency of vibration. For efficient control of building vibration, required damping of viscoelastic damping device need be estimated and dynamic analysis method which can estimate the response of building structure with viscoelastic damper system is indispensable. In this paper, an efficient dynamic analysis method of a building structure with viscoelastic dampers is proposed. Efficiency and accuracy of the proposed method are verified comparing analytic results with shaking table test results using reduced building models.

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Dynamics of multilayered viscoelastic beams

  • Roy, H.;Dutt, J.K.;Datta, P.K.
    • Structural Engineering and Mechanics
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    • v.33 no.4
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    • pp.391-406
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    • 2009
  • Viscoelastic materials store as well as dissipate energy to the thermal domain under deformation. Two efficient modelling techniques reported in literature use coupled (thermo-mechanical) ATF (Augmenting Thermodynamic Fields) displacements and ADF (Anelastic Displacement Fields) displacements, to represent the constitutive relationship in time domain by using certain viscoelastic parameters. Viscoelastic parameters are first extracted from the storage modulus and loss factor normally reported in hand books with the help of Genetic Algorithm and then constitutive relationships are used to obtain the equations of motion of the continuum after discretizing it with finite beam elements. The equations of motion are solved to get the frequency response function and modal damping ratio. The process may be applied to study the dynamic behaviour of composite beams and rotors comprising of several viscoelastic layers. Dynamic behaviour of a composite beam, formed by concentric layers of steel and aluminium is studied as an example.

Study of viscoelastic model for harmonic waves in non-homogeneous viscoelastic filaments

  • Kakar, Rajneesh;Kaur, Kanwaljeet;Gupta, Kishan Chand
    • Interaction and multiscale mechanics
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    • v.6 no.1
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    • pp.31-50
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    • 2013
  • A five parameter viscoelastic model is developed to study harmonic waves propagating in the non-homogeneous viscoelastic filaments of varying density. The constitutive relation for five parameter model is first developed and then it is applied for harmonic waves in the specimen. In this study, it is assumed that density, rigidity and viscosity of the specimen i.e., rod are space dependent. The specimen is non-homogeneous, initially unstressed and at rest. The method of non-linear partial differential equation has been used for finding the dispersion equation of harmonic waves in the rods. A simple method is presented for reflections at the free end of the finite non-homogeneous viscoelastic rods. The harmonic wave propagation in viscoelastic rod is also presented numerically with MATLAB.