• Earthquakes and Structures
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• 제13권4호
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• pp.409-419
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• 2017

In order to analyze the vibration control effect of viscous damper in the concrete archaized buildings with lintel-column joints under seismic action, 3 specimens were tested under dynamic excitation. Two specimens with viscous damper were defined as the controlled component and one specimen without viscous damper was specified as the non-controlled component. The loading process and failure patterns were obtained from the test results. The failure characteristics, skeleton curves and mechanical behavior such as the load-displacement hysteretic loops, load carrying capacity, degradation of strength and rigidity, ductility and energy dissipation of the joints were analyzed. The results indicate that the load-bearing capacity of the controlled component is significantly higher than that of the non-controlled component. The former component has an average increase of 27.4% in yield load and 22.4% in ultimate load, respectively. Meanwhile, the performance of displacement ductility and the ability of energy dissipation for the controlled component are superior to those of the non-controlled component as well. Compared with non-controlled component, equivalent viscous damping coefficients are improved by 27.3%-30.8%, the average increase is 29.0% at ultimate load for controlled component. All these results reflect that the seismic performance of the controlled component is significantly better than that of the non-controlled component. These researches are helpful for practical application of viscous damper in the concrete archaizing buildings with lintel-column joints.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.511-518
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• 2006

In this study, seismic response mitigation effect of an MR damper generating response-dependent frictional force is investigated. It has been reported in previous studies that passively operated MR damper with constant input current doesn't show better control performance than semi-active MR damper with varying input current calculated by control algorithms such as linear quadratic regulator and sliding mode control. However, in order to operate the MR damper semi-actively, other control systems besides the damper itself such as sensors for measuring structural responses and controller for calculating optimal input current are necessary, which deteriorate the economical efficiency. This study presents a MR damper generating frictional force of which magnitude is controlled in accordance to the displacement and velocity transferred to the damper. Numerical analyses results indicate that the performance of the response dependent MR damper is closely related with the range of the friction force and it can be designed to short better control performance than the passive MR damper.

• 한국지진공학회논문집
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• 제21권5호
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• pp.215-226
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• 2017

In this paper, an experimental study was carried out for vibration control of cable bridges with structurally flexible characteristics. For the experiment on vibration control, a model bridge was constructed by reducing the Seohae Grand Bridge and the shear type MR damper was designed using the wind load response measured at Seohae Grand Bridge. The shear type MR damper was installed in the vertical direction at the middle span of the model bridge, and dynamic modeling was performed using the power model. The tests of the vibration control were carried out by non-control, passive on/off control and Lyapunov control method on model bridge with scaled wind load response. The performance of the vibration control was evaluated by calculating absolute maximum displacement, RMS displacement, absolute maximum acceleration, RMS acceleration, and size of applied power using the response (displacement, acceleration, etc.) from the model bridge. As a result, the power model was effective in simulating the nonlinear behavior of the MR damper, and the Lyapunov control method using the MR damper was able to control the vibration of the structure and reduce the size of the power supply.

• 한국가스학회지
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• 제12권4호
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• pp.41-45
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• 2008

본 논문은 외부의 충격력을 차단하고, 충격에너지를 흡수하는 헬멧의 강도안전과 변형거동에 대한 수치적 연구를 수행한 것이다. 기존헬멧과, 보강뼈대와 주름댐퍼를 추가적으로 설치한 4개의 헬멧모델에 대한 응력 및 변형거동을 유한요소법으로 해석하였다. 헬멧의 정상부에 보강뼈대를 설치하면 헬멧의 강도 안전 향상에 유용하고, 헬멧의 하단부에 주름댐퍼를 설치하면 충격에너지 흡수효과가 우수하다는 것을 FEM 해석결과를 통해 확인할 수 있었다. 따라서 첨단헬멧을 안전하게 설계하기 위해서는 보강뼈대와 주름댐퍼를 새로운 설계요소로 고려할 것을 권장한다.

• 한국소음진동공학회논문집
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• 제14권5호
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• pp.377-384
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• 2004

An Amplitude Proportional Friction Damper (APFD), in which the friction force is proportional to the system displacement, has been introduced and mathematically modeled. To understand the damping characteristics of APFD, analytical solutions for the impulse response has been derivedand compared to the viscous damper. It is found that APFD system has very similar damping characteristics to viscous damper even though it is a friction damper. APFD may be used as a cost-effective substitution for the viscous damper and could also be used to improve the simple friction or Coulomb dampersince APFD works with no stick-slip and always returns to original position when external disturbance is disappeared.

• 한국공간구조학회논문집
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• 제19권3호
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• pp.101-109
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• 2019

In order to develop the compatible damping device in various vibration source, a hybrid wall-type damper combining slit and friction damper in parallel was developed. Cyclic loading tests and two-story RC reinforced frame tests were performed for structural performance verification. As a result of the 5-cyclic loading test according to KBC-2016 and low displacement cyclic fatigue test, The hybrid wall type damper increased its strength and the ductility was the same as that of the slit damper. In addition, As a result of the two-layer frame test, the reinforced frame had about twice the strength of the unreinforced frame, and the story drift ratio was satisfied to Life Safety Level.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 봄 학술발표회 논문집
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• pp.348-354
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• 2003

This study outlines the analysis of toggle system and the vibration control performance when the toggle-rotational inertia damper system was applied to a structure. Numerical analysis shows that the relative displacement of the structure can be amplified by amplification mechanism of the toggle system and the capacity of the damper can be reduced without the loss of vibration control performance. It is also observed that vibration control effects is caused by the increase of equivalent mass due to the rotational inertia of damper.

• 한국소음진동공학회논문집
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• 제20권1호
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• pp.22-28
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• 2010

Approximate analysis for a building installed with a friction damper is performed to get insight of its dynamic behavior. Energy balance equation is used to have a closed analytical form solution of dynamic magnification factor(DMF). It is found out that DMF is dependent on friction force ratio and resonance frequency. Approximation of DMF and equivalent damping ratio of a friction damper is proposed with such assumption that the building with a friction damper shows harmonic steady-state response and narrow banded response behavior near resonance frequency. Linear transfer function from input external force to output building displacement is suggested from the simplified DMF equation. Root mean square of a building displacement is derived under earthquake-like random excitation. Finally, design procedure of a friction damper is proposed by finding friction force corresponding to target control ratio. Numerical analysis is carried out to verify the proposed design procedure.

• 한국소음진동공학회논문집
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• 제20권7호
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• pp.658-664
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• 2010

A control element drive mechanism(CEDM) is a reactor regulating system, which inserts, withdraws or maintains a control rod containing a neutron absorbing material within a reactor core to control the reactivity of the core. The ball-screw type CEDM for the integral reactor has a spring-damper system to reduce the impact force due to the scram of the CEDM. This paper describes the experimental results to obtain the drop and damping characteristics of the CEDM. The drop tests are performed by using a drop test rig and a facility. A drop time and a displacement after an impact are measured using a LVDT. The influences of the rod weight, the drop height and the flow area of hydraulic damper on the drop and damping behavior are also estimated on the basis of test results. The drop time of the control element is within 4.5s to meet the design requirement, and the maximum displacement is measured as 15.6 mm. It is also found that the damping system using a spring-hydraulic damper plays a good damper role in the CEDM.

• 대한건축학회연합논문집
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• 제21권1호
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• pp.185-192
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• 2019

Recently, the frequency and magnitude of earthquakes are increasing worldwide. In Korea, the Gyeongju earthquake (2016) and the Pohang earthquake (2017) caused structural damage to many buildings. Since Korea's seismic design standards were revised to three or more stories in 2005, five-story buildings built before the revision are not designed to be earthquake-resistant. In this situation, if strong earthquake occurs in Korea, there will be great damage. To prevent this, seismic retrofit of buildings should be necessary. The seismic retrofit of classical method is mainly used to reduce the displacement generated in the structure by strengthening stiffness and strength. However, since this method increases the base shear force of the structure, it is difficult to apply it to buildings which have weak foundation. Therefore, in this study, we propose the damper system that reduces the response displacement of buildings and suppresses the increase of base shear force by using high damping rubber and steel. And the seismic performance of the damper system is verified through the experiment and the seismic analysis of the structure.