• 도시과학
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• 제11권1호
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• pp.1-8
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• 2022

As the magnitude and frequency of earthquakes increase in Korea, interest in earthquake damage reduction technology has increased. Therefore, research on vibration damping devices that directly respond to seismic loads is being actively researched. After an earthquake, damage or destruction of the device occurs due to the yield of materials, and thus it takes considerable cost and time for restoration and replacement. To supplement the problems of the existing earthquake damage reduction technology, a study was conducted on the recentering smart damper that can be used continuously after an earthquake. In this study, the recentering smart damper that can be restored to its original shape after load removal was developed using superelastic shape memory alloy, pre-compressed polyurethane. General steel was commonly applied to verify the seismic performance of the superelastic shape memory alloy, and the performance of the smart damper was verified according to the amount of polyurethane pre-compressed

• Steel and Composite Structures
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• 제44권4호
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• pp.569-586
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• 2022

This study introduces a novel friction damper as a component of a recentering frame connection, to solve the problem of structural repair costs, caused by stiffness deterioration and brittle fracture of the central brace frame (CBF). The proposed damper consists of shape memory alloy (SMA) bars with pretension applied to them to improve the stability. SMAs reduce the residual displacement by virtue of the properties of the materials themselves; in addition, a pretension can be applied to partially improve their energy dissipation capacity. The damper also consists of a friction device equipped with friction bolts for increased energy dissipation. Therefore, a study was conducted on the effects of the friction device as well as the pretension forces on the friction damper. For performance verification, 12 cases were studied and analyzed using ABAQUS program. In addition, the friction and pretension forces were used as variables in each case, and the results were compared. As a result, when the pretension and friction force are increased, the energy dissipation capacity gradually increases by up to about 94% and the recentering capacity decreases by up to about 55%. Therefore, it has been shown that SMA bars with adequate pretension in combination with bolts with adequate frictional force effectively reduce residual deformation and increase damper capacity. Thus, this study has successfully proposed a novel friction damper with excellent performance in terms of recentering and energy dissipation capacity.

• 대한토목학회논문집
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• 제34권2호
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• pp.377-387
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• 2014

본 연구는 지진에 대한 구조물의 손상을 최소화 하기 위하여 슬립 저항력을 활용한 새로운 형태의 마찰 댐퍼형 가새 시스템의 설계와 개발을 주로 다루고자 한다. 가새 부재 내에서 전단력에 의한 마찰 거동으로 상당량의 에너지를 수동적으로 소산하기 위하여 플레이트 전단 이음부 위에 슬롯 형태의 볼트 구멍을 설치한다. 여기에 전단 마찰 거동으로 인해 발생되는 잔류변형을 줄이고자 상온에서 원형복원이 가능한 초탄성 형상합금 와이어를 꼬아서 만든 연선을 설치하여 댐퍼 시스템 내에 복원성을 증진 시켰다. 기존에 주로 사용된 수동적인 변위 제어 장치와 비교하여 본 연구에서 다루고자 하는 자동복원이 가능한 마찰 댐퍼형 가새 시스템은 중심 가새 프레임 구조물에 손쉽게 설치하여 지진발생 후에 구조물에 발생하는 층간 잔류변위를 최소화하여 유지 보수에 소모되는 비용의 대폭적인 절감을 기대할 수 있다. 본 연구에서는 자동복원이 가능한 마찰 댐퍼형 가새 시스템의 역학적인 거동 메커니즘을 살펴보고 실험값으로 보정되어 신뢰성을 확보한 스프링 모델을 사용하여 해석을 실시하였다. 시스템에 다양한 설계 변수를 적용하여 복원성과 에너지 소산 능력 측면에서 제안된 댐퍼의 성능 동향을 분석을 하고 최적의 설계 방식을 제안하고자 한다. 마지막으로 자동복원이 가능한 마찰 댐퍼를 중심 가새 프레임 구조물에 설치하여 비선형 동적 해석을 실시하고 기존의 시스템과 비교하여 성능적인 우수성을 입증하고자 한다.

• Steel and Composite Structures
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• 제32권3호
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• pp.373-388
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• 2019

This study proposes a new concept of an axial damper using the combination of shape memory alloy (SMA), friction devices, and polyurethane springs. Although there are many kinds of dampers to limit the damages, large residual deformation may happen and it causes much repairing cost for restoring the structure to the initial position. Also in some of the dampers, a special technology for assembling and fabricating is needed. One of the most important advantages of this damper is the ability to remove all the residual deformation using SMA plates and simple assembling without any special technology to fabricate. In this paper, four different dampers (in presence or omission of friction devices and polyurethane springs) are investigated. All four cases are analyzed in ABAQUS platform under cyclic loadings. In addition, the SMA plates are replaced by steel ones in four cases, and the results are compared to the SMA dampers. The results show that the axial polyurethane friction (APF) damper could decrease the residual deformation effectively. Also, the damper capacity and dissipated energy could be improved. The analysis showed that APF damper is a good recentering damper with a large amount of energy dissipation and capacity, among others.

• Smart Structures and Systems
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• 제25권2호
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• pp.241-254
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• 2020

Using confined shape memory alloy (SMA) bar or plate, this study proposes an innovative self-centering damper. The damper is essentially properly machined SMA core, i.e., bar or plate, that encased in buckling-restrained device. To prove the design concept, cyclic loading tests were carried out. According to the test results, the damper exhibited desired flag-shape hysteretic behaviors upon both tension and compression actions, although asymmetric behavior is noted. Based on the experimental data, the hysteretic parameters that interested by seismic applications, such as the strength, stiffness, equivalent damping ratio and recentering capacity, are quantified. Processed in the Matlab/Simulink environment, a preliminary evaluation of the seismic control effect for this damper was conducted. The proposed damper was placed at the first story of a multi-story frame and then the original and controlled structures were subjected to earthquake excitations. The numerical outcome indicated the damper is effective in controlling seismic deformation demands. Besides, a companion SMA damper which represents a popular type in previous studies is also introduced in the analysis to further reveal the seismic control characteristics of the newly proposed damper. In current case, it was found that although the current SMA damper shows asymmetric tension-compression behavior, it successfully contributes comparable seismic control effect as those having symmetrical cyclic behavior. Additionally, the proposed damper even shows better global performance in controlling acceleration demands. Thus, this paper reduces the concern of using SMA dampers with asymmetric cyclic behavior to a certain degree.