• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.10a
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• pp.359-366
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• 1999

This paper is a study on the seismic design and test of viscoelastic dampers in regions of moderate seismicity. First moderate seismic waves are generated with measured strong seismic data based on the theory of effective peak acceleration. Then their response spectrums are compared each other to estimate the required damping to attenuate the vibration. As relatively smaller damping is required in the regions of moderate seismicity than in the regions of strong seismicity proper viscoelastic dampers can be designed according to the estimated damping. Finally a test building model is designed and the viscoelastic dampers are installed for the experimental study under moderate and strong earthquakes, It is found that viscoelastic dampers with low damping capacity developed in this study are enough to reduce the building response in regions of moderate seismicity.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.435-441
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• 2003

본 논문에서는 Maximum Energy Dissipation Algorithm(MEDA) 사장교의 MR댐퍼제어에 적용하고자 한다 MR댐퍼의 제어를 위해서 여러 제어 이론들이 제안되었으나, 각각의 특성에도 불구하고 성능면에서는 큰 차이가 없다 MEDA는 Lyapunove 직접법을 바탕으로 군성되는 제어이론으로써, 15년전에 제안되었음에도 실제 토목구조물에는 적용된 바 없어 그 성능 및 장점이 제대로 검증되지 않았다. 따라서 본 논문에서는 벤치마크 사장교 수치예제를 통해서, MEDA의 토목구조물에의 적용성을 성능(performance)과 강인성(robustness) 측면에서 분석하려한다. 수치예제에서 다양한 지진에 대한 층간변위, 가속도, 그리고 상대변위의 각 제어기법에 의한 감소량은 벤치마크문제에 정의된 평가지수(evaluation criteria)를 사용하였다.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.467-472
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• 2003

The objective of optimal placement of dampers for a structure is to maximize the effectiveness of the vibration control with the same number of dampers. While many optimal placement methods of linear viscous dampers have been proposed and used, there are only a few methods for MR dampers. Here some optimal location indices for MR dampers are proposed, which are similar to those for linear viscous dampers and show how large the structural responses on each floor we. Every time an additional MR damper is implemented, the optimal location index on each floor is measured, and then the next damper is installed on the floor with the maximum location index. In these sequential procedures, the peak interstory drift, the peak interstory velocity and the absolute acceleration of each floor are selected as the optimal location indeices. Four different earthquakes with various scales are loaded to the 20-story nonlinear benchmark building model (Otori et at. 2000, 2002). Passive On/Off algorithms are used in order to represent the control algorithm of MR dampers.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.382-389
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• 2006

구조 재료와 시공기술의 발달로 구조물은 높고 길게 설계할 수 있게 되었으나, 그에 따른 진동 문제와 사용성에 관한 문제가 발생하였고 구조물의 과다한 변위는 구조물에 심각한 손상을 발생 시켰다. 이러한 구조물의 진동 문제를 해결하기 위하여 본 논문에서는 확률신경망이론을 사용한 구조물의 능동제어방법을 제안하였다. 구조물의 제어를 위하여 LQR 제어알고리즘을 이용하여 구조물의 상태벡터와 제어력을 구한 후, 상태벡터를 입력으로 제어력을 출력으로 하는 확률신경망의 훈련패턴을 구성하였다. 제안된 방법을 사용하여 지진하중을 받는 3층 빌딩구조물을 제어하였고, 기존의 인공신경망의 제어 결과와 비교하였다.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.471-478
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• 2006

This paper presents the results of experimental studies of the mechanical characteristics of the Coil Spring and Viscous Damper system. The Coil Spring and Viscous Damper systems were selected for the isolation of Emergency Diesel Generator (EDG) which is located in Nuclear Power Plant (NPP). The Coil Spring and Viscous Damper systems were developed for, the operating vibration isolation and seismic isolation for scaled Model EDG System. The damping properties of the viscous damper changes as the variation of velocity. As a results, nonlinear damping characteristics of viscous damper system were evaluated.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.337-344
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• 2006

This paper is concerned with the simplified criterion given in ASCE 4-98, for determining whether soil-structure interaction (SSI) analysis is required for seismic response analysis of nuclear power plant structures. In this study, the criterion is evaluated for a couple of example structures including an existing nuclear power plant and the Hualien large-scale seismic test building. Forced vibration analysis and seismic response analysis are carried out using the simple stick model with soil springs and an elaborated SSI analytical model. From the numerical analyses, it is found that the criterion may not allow the fixed-base analysis for bedrock with shear wave velocity of greater than 1,100m/s which is a well-known criterion for a rock site. In addition, it is indicated that peak amplification as well as the peak broadening specified in NRC RG 1.122. shall be considered to include the effects of SSI.

• Structural Engineering and Mechanics
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• v.10 no.6
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• pp.561-575
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• 2000

Microvibration of high technology facilities, such as semiconductor plants and facilities with high precision equipments, due to nearby road and rail traffic has attracted considerable attention recently. In this paper, a preliminary study is conducted for the possible use of various protective systems and their performance for the reduction of microvibration. Simulation results indicate that passive base isolation systems, hybrid base isolation systems, passive floor isolation systems, and hybrid floor isolation systems are quite effective and practical. In particular, the performances of hybrid floor isolation systems are remarkable. Further, passive energy dissipation systems are not effective for the reduction of microvibration. Finally, the protections against both microvibration and earthquake are also investigated and presented.

• Smart Structures and Systems
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• v.23 no.4
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• pp.337-345
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• 2019

This work resumes a research that proposes the use of the technique based on the dissipation energy of the shape memory alloy (SMA) ties. It focuses principally on the assessment of the effectiveness of the use of these smart materials on displacements, accelerations and the stresses of the minaret of the great mosque of Ajloun in Jordan. The 3-D finite element model of the minaret is performed by the ANSYS software. First of all, the proposed model is calibrated and validated according to the experimental results gathered from ambient vibration testing results. Then, a nonlinear transient analysis is considered, when the El-Centro earthquake is used as the input signal. Different simulating cases concerning the location, number and type of SMA devices are proposed in order to see their influence on the seismic response of the minaret. Hence, the results confirm the effectiveness of the proposed SMA device.

• International Journal of High-Rise Buildings
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• v.10 no.2
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• pp.123-135
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• 2021

Solid Viscoelastic Coupling Dampers (VCDs) provide distributed damping that improves the dynamic performance of tall buildings for both wind-storms and earthquakes for all amplitudes of vibration. They are configured in place of typical structural members in tall buildings and therefore do not occupy any architectural space. This paper summarizes the research and development at the University of Toronto in collaboration with Nippon Steel Engineering, 3M and Kinetica over the past two decades. In addition, impact studies on buildings incorporating the VCDs are presented, consisting of a wind sensitive 66-story building in Toronto, a dual-wind and seismic performance-based design of a 4-tower development in Manila and finally a 630 meter Megatall building in Southeast Asia in a severe seismic environment. In all applications the VCDs are shown to provide significant benefits in the dynamic performance under both wind and earthquake loading in a cost-effective manner.

• Coupled systems mechanics
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• v.11 no.5
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• pp.373-387
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• 2022

In this paper,soil-structure interaction effects on the seismic response of multistory frame structure on raft foundation are numerically analyzed. The foundation soil profile is assumed to consists of a clay layer of variable thicknessresting on bedrock. Amodified plane-strain numerical model isformed in the software Plaxis, and both free vibration analysis, and earthquake analysis for a selected ground motion accelerogram are performed. The behavior of the structure is assumed to be linear elastic with Rayleigh viscous damping included. The behavior of the clay layer is modeled with a Hardening soil model with small strain stiffness. The computed results in terms of fundamental period and structural horizontal displacementsfor the case of fixed base and for different thicknesses of clay layer are presented, compared, and discussed.