The Dynamic Mechanical Model of Viscoelastic Dampers Relying on the Frequency and Temperature

Huang, Y. Henry; Kato, Takashi; Wada, Akira; Iwata, Mamoru; Takeuchi, Tōru; Okuma, Kiyoshi

doi:10.3130/aijs.64.91_2

Cited by 10 publications

(2 citation statements)

References 18 publications

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“…Under seismic loading, the values of k vem and c vem in Equation () are not stable, as ω vem , G , and η are time‐variant parameters throughout the loading history. To address this, the following Equation (6) developed by Huang et al 11 was adopted to compute the transient value of ω vem :

ω_{normalvem}^{t} = \sqrt{\frac{\sum_{j = 1}^{n} (|| {((), {\overset{d}{true}}_{normalvem}^{t})}^{2} - {((), {\overset{d}{true}}_{normalvem}^{t - j Δ t})}^{2})}{\sum_{j = 1}^{n} (|| {((), d_{normalvem}^{t})}^{2} - {((), d_{normalvem}^{t - j Δ t})}^{2})}},

where

ω_{vem}^{t}

is the kinematic circular frequency of the LVEM at time t ;

d_{vem}^{t}

and

d_{vem}^{t - j normalΔ t}

are the shearing displacement of the LVEM at time t and time t – j Δ t , respectively; and

{\dot{d}}_{vem}^{t}

and

{\dot{d}}_{vem}^{t - j normalΔ t}

are the shearing velocity of the LVEM at time t and time t – j Δ t , respectively. In particular, n is the counted number of steps for computing ω vem , that is, n = [0.25 T p /Δ t ], which is the natural number being closest to 0.25 T p /Δ t .…”

Section: Mechanical Model Of Lvem Under Combined Compression‐shearmentioning

confidence: 99%

Steel frame with aseismic floor: From the viscoelastic decoupler model to the elastic structural response

Xiang

Koetaka

Nishira

2021

Earthq Engng Struct Dyn

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By installing laminated viscoelastic materials (LVEM) between floor slabs and steel beams, the lateral motions of the floor and the frame are decoupled and the structural seismic response is mitigated. This paper presents a study of the elastic seismic performance of the steel frame with this floor system (hereafter termed the aseismic floor). First, the dynamic model of an LVEM under the combined precompression (vertical) and shear (lateral) is checked by experiment. The dynamic shearing behavior of the precompressed LVEM could be well simulated by the pure‐shear model (without precompression) using the modified shear area‐to‐thickness ratio. The storage modulus and the loss factor of the precompressed LVEM could be deemed the same as those without precompression. Second, the time‐varying dynamic properties of LVEM during the seismic response history are processed. In the processing, the transient frequency of LVEM is assumed to be equal to the fundamental frequency of the accordant conventional frame, and the dynamic property of the structure equipped with the aseismic floor is assumed stable throughout the response history. The accuracy of the processing is validated via numerical analyses. Third, based on the processed structural dynamic properties, the effectiveness of a complex Complete‐Quadratic‐Combination (CQC) method for predicting the peak structural seismic response is checked. The CQC method is recalibrated to account for the deviation between the pseudo‐ and relative velocities of the modal oscillators. The recalibrated CQC method could well predict the interstory drift of the frame and the shear deformation of the LVEM.

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ω_{normalvem}^{t} = \sqrt{\frac{\sum_{j = 1}^{n} (|| {((), {\overset{d}{true}}_{normalvem}^{t})}^{2} - {((), {\overset{d}{true}}_{normalvem}^{t - j Δ t})}^{2})}{\sum_{j = 1}^{n} (|| {((), d_{normalvem}^{t})}^{2} - {((), d_{normalvem}^{t - j Δ t})}^{2})}},

where

ω_{vem}^{t}

is the kinematic circular frequency of the LVEM at time t ;

d_{vem}^{t}

and

d_{vem}^{t - j normalΔ t}

are the shearing displacement of the LVEM at time t and time t – j Δ t , respectively; and

{\dot{d}}_{vem}^{t}

and

{\dot{d}}_{vem}^{t - j normalΔ t}

Section: Mechanical Model Of Lvem Under Combined Compression‐shearmentioning

confidence: 99%

Steel frame with aseismic floor: From the viscoelastic decoupler model to the elastic structural response

Xiang

Koetaka

Nishira

2021

Earthq Engng Struct Dyn

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“…Use of the Kelvin model was also examined by Soda and Takahashi [1997] and Huang et al [1999]. To more accurately represent the behaviour of VE damped structures, use of models with more damper and spring elements was proposed by researchers such as Soda and Takahashi [2000] and Kaneko and Nakamura [1998].…”

Section: Introductionmentioning

confidence: 99%

Untitled

OKADA¹

2006

J. Earth. Eng.

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The objective of this paper is to introduce a Rational Polynomial Approximation (RPA) method for modelling the response of structures that contain discrete elements with linear frequency-dependent stiffness and damping characteristics. The RPA method consists of two steps: First, system identification is performed to obtain a rational polynomial approximation for the system's transfer functions. Then, a time-domain model for the system is realised. The main advantage of the RPA method is that the resulting model is a system of ordinary differential equations, facilitating time history analysis of both linear and nonlinear structures using standard time-step integration algorithms and procedures.Viscoelastic (VE) dampers comprise one of the primary classes of frequencydependent dampers with both frequency-dependent stiffness and damping. VE dampers are used for mitigation of seismic-and wind-induced structural vibration. When using VE dampers in analysis, effective modelling of the frequency-dependent characteristics of the VE damper plays a key role in accurate simulation of structural responses.Following a description of the theory behind the RPA method, the efficacy of the method is verified through several numerical examples employing VE damped structures. The results are compared with Kasai's fractional derivative model for VE dampers. 97 J. Earth. Eng. 2006.10:97-125. Downloaded from www.worldscientific.com by UNIVERSITY OF OTAGO on 07/04/15. For personal use only. 98 R. Okada et al.Application of the RPA method to nonlinear structures is also given. The RPA method is shown to be effective and efficient for modelling VE damped structure.

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Single-story steel structure with LVEM-isolated floor: Elastic seismic performance and design response spectrum

Xiang

Koetaka

Okuda

2019

Engineering Structures

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The Dynamic Mechanical Model of Viscoelastic Dampers Relying on the Frequency and Temperature

Cited by 10 publications

References 18 publications

Steel frame with aseismic floor: From the viscoelastic decoupler model to the elastic structural response

Steel frame with aseismic floor: From the viscoelastic decoupler model to the elastic structural response

Untitled

Single-story steel structure with LVEM-isolated floor: Elastic seismic performance and design response spectrum

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