• Earthquakes and Structures
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• 제2권3호
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• pp.297-321
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• 2011

The seismic design of a two-storey precast reinforced-concrete building structure equipped with viscous dampers is presented in this paper with twofold purpose. The first goal is to verify the applicability of a practical procedure for the identification of the mechanical characteristics of the viscous dampers which allow to achieve target performance levels, originally proposed by the authors for moment-resisting building frames, also with reference to "pendular" structures. The second goal is to investigate the effectiveness of the use of viscous dampers (as compared with traditional lateral-resisting stiff braces) for the seismic design of precast not moment-resisting concrete structures.

• Earthquakes and Structures
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• 제1권3호
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• pp.307-326
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• 2010

This paper is concerned with the optimal seismic design of added viscous dampers in yielding plane frames. The total added damping is minimized for allowable values of local performance indices under the excitation of an ensemble of ground motions in both regular and irregular structures. The local performance indices are taken as the maximal inter-story drift of each story and/or the normalized hysteretic energy dissipated at each of the plastic hinges. Gradients of the constraints with respect to the design variables (damping coefficients) are derived, via optimal control theory, to enable an efficient first order optimization scheme to be used for the solution of the problem. An example of a ten story three bay frame is presented. This example reveals the following 'fully stressed characteristics' of the optimal solution: damping is assigned only to stories for which the local performance index has reached the allowable value. This may enable the application of efficient and practical analysis/redesign type methods for the optimal design of viscous dampers in yielding plane frames.

• Structural Engineering and Mechanics
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• 제27권5호
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• pp.541-554
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• 2007

A simplified yet effective design procedure for viscous dampers was presented based on improved capacity spectrum method in the context of performance-based seismic design. The amount of added viscous damping required to meet a given performance objective was evaluated from the difference between the total demand for effective damping and inherent damping plus equivalent damping resulting from hysteretic deformation of system. Application of the method is illustrated by means of two examples, using Chinese design response spectrum and mean response spectrum. Nonlinear dynamic analysis results indicate that the maximum displacements of structures installed with supplemental dampers designed in accordance with the proposed method agree well with the given target displacements. The advantage of the presented procedure over the conventional iterative design method is also highlighted.

• Structural Engineering and Mechanics
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• 제25권1호
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• pp.21-37
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• 2007

In this study a stochastic approach for linear viscous dampers design adopted for seismic protection of buildings is developed. Devices optimal placement into the main structure and their mechanical parameters are attained by means of a reliability-based optimum design criterion, in which an objective function (O.F.) is minimized, subject to a stochastic constraint. The seismic input is modelled by a non stationary modulated Kanai Tajimi filtered stochastic process. Building is represented by means of a plane shear type frame model. The selected criterion for the optimization searches the minimum of the O.F., here assumed to be the cost of the seismic protection, i.e., assumed proportional to the sum of added dampings of each device. The stochastic constraint limits a suitable approximated measure of the structure failure probability, here associated to the maximum interstorey drift crossing over a given threshold limit, related, according with modern Technical Codes, to the required damage control.

• Earthquakes and Structures
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• 제20권2호
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• pp.225-238
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• 2021

Supplemental passive dampers are widely employed to improve the structural performance of buildings under seismic excitations. Nevertheless, the added damping could be counter-productive if the axial forces induced by the damper reaction forces are not routed properly in the columns. A few researchers engaged to optimize the width-wise damper arrangement to improve the delivered path of the axial column forces. However, most of these studies are limited under the design-based seismic level and few of them has evaluated the collapse performance of buildings under strong earthquakes. In this paper, the strategic width-wise placement method of viscous dampers is explored regarding the building performance under collapse state. Two realistic steel buildings with different storeys are modelled and compared to explore higher mode effects. Each building is designed with four different damper arrangement scenarios based on a classic damper distribution method. Both a far-fault and a near-fault seismic environment are considered for the buildings. Incremental Dynamic Analysis (IDA) is performed to evaluate the probability of collapse and the plastic mechanism of the retrofitted steel buildings.

• Structural Engineering and Mechanics
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• 제16권2호
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• pp.177-193
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• 2003

This paper presents an illustrative example of the advantages offered by inserting added viscous dampers into shear-type structures in accordance with a special scheme based upon the mass proportional damping (MPD) component of the Rayleigh viscous damping matrix. In previous works developed by the authors, it has been widely shown that, within the class of Rayleigh damped systems and under the "equal total cost" constraint, the MPD system provides best overall performance both in terms of minimising top-storey mean square response to a white noise stochastic input and maximising the weighted average of modal damping ratios. A numerical verification of the advantages offered by the application of MPD systems to a realistic structure is presented herein with reference to a 4-storey reinforced-concrete frame. The dynamic response of the frame subjected to both stochastic inputs and several recorded earthquake ground motions is here analysed in detail. The results confirm the good dissipative properties of MPD systems and indicate that this is achieved at the expense of relatively small damping forces.

• 한국전산구조공학회논문집
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• 제15권3호
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• pp.421-432
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• 2002

본 연구에서는 진동제어를 목적으로 강성이 평면에서 비대칭적으로 분포된 구조물에 감쇠기를 설치할 경우 감쇠편심과 강성편심에 따른 모드특성 및 변위응답의 변화에 관하여 연구하였다 모드 특성으로는 고유진동수, 모드 감쇠비, 모드참여계수, 동적 증폭계수 등의 변화를 분석하였으며, 변위는 지진이력에 대한 약변, 강변, 무게중심 등에서의 변위를 비교하였다. 또한 이를 바탕으로 비틀림 응답을 최소화하기 위한 감쇠기의 적정 감쇠 편심 및 적정 감쇠 분배 문제에 대해 논하였으며, 단층구조물에서 유도된 적정 감쇠분배 방법을 다층구조뭍에 적용하고 그 효과를 확인하였다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.335-340
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• 2002

In this study procedure for finding out additional viscous damping required to meet a performance target of an asymmetric nonlinear structure is developed based on the design concept of Pauly. The behavior of an asymmetric nonlinear structure after yielding is investigated. Finally the required amount of equivalent damping is obtained using the direct-displacement-based design method without carrying out time-consuming nonlinear dynamic time history analysis.

• Earthquakes and Structures
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• 제1권3호
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• pp.289-306
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• 2010

A gradient-based evolutionary optimization methodology is presented for finding the optimal design of viscous dampers to minimize an objective function defined for a linear multi-storey structure. The maximum value along height of the transfer function amplitudes for the interstorey drifts is taken as the objective function. Since the ground motion includes various uncertainties, the optimal damper placement may be different depending on the ground motion used for design. Furthermore, the transfer function treated as the objective function depends on the properties of structural parameters and added dampers. This implies that a more robust damper design is desired. A reliable and robust damping design system against any unpredictable ground motions can be provided by minimizing the maximum transfer function. Such design system is proposed in this paper.