• Earthquakes and Structures
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• 제27권1호
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• pp.69-82
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• 2024

In the conventional seismic design approach for a bridge pier, the function of the stopper, and shear key are to serve as mechanisms for unseating prevention devices that retain and transmit the lateral load to the pier under strong earthquakes. This frequently inflicts immense shear forces and bending moments concentrated at the plastic hinge zone. In this study, a shear panel damper plus gap (SPDG) is proposed as a low-cost alternative with high energy dissipation capacity to improve the seismic performance of the pier. Therefore, this study aimed to investigate the seismic performance of the pre-stressed concrete I girder (PCI-girder) bridge equipped with SPDG. The bridge structure was analyzed using nonlinear time history analysis with seven-scaled ground motion records using the guidelines of ASCE 7-10 standard. Consequently, the implementation of SPDG technology on the bridge system yielded a notable decrease in maximum displacement by 41.49% and a reduction in earthquake input energy by 51.05% in comparison to the traditional system. This indicates that the presence of SPDG was able to enhance the seismic performance of the existing conventional bridge structure, enabling an improvement from a collapse prevention (CP) level to an immediate occupancy (IO).

• Structural Engineering and Mechanics
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• 제89권5호
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• pp.507-524
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• 2024

Since the cost of reconstruction is very high and the structure may have been damaged by an earthquake, we must retrofit the structure. Therefore, the importance of studying this issue is very high in order to achieve the desired resistance against the regulations. The present study involved the numerical and experimental analysis of nine concrete frames, consisting of three concrete frames, three concrete frames with bracing, and three concrete frames with a TADAS damper. The purpose of this study is to strengthen the damaged concrete frame using braces and TADAS dampers. Observations were made of the frames as they were subjected to controlled displacement. Also, ABAQUS software was used to compare numerical and experimental results. According to the results, the software was sufficiently capable of modeling the studied frames. Additionally, a parametric study was conducted on the thickness and number of bending plates. Thickness increases from 8 mm to 12 mm, 8 mm to 15 mm, and 8 mm to 20 mm, increasing the base shear by about 6.7%, 11.1%, and 25%, respectively. Furthermore, increasing the number of plates from 4 to 5, 4 to 6, and 4 to 7 increased base shears by about 4.5%, 8.4%, and 14%, respectively.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.169-173
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• 2007

To improve the riding comfort and to increase the speed of high-speed railway, it needs active suspension system for railway more and more. In Korea, Korean Train Express (KTX) was opened to commercial traffic 3years ago. Korea High-speed Railway (HSR 350x) was developed and succeeded 350km/h test run by Korean government and several related institute. With the increase of the speed, the vibration control of the high-speed railway becomes important to improve high ride quality. To meet this request, the authors suggest the installation of lateral semi-active damper to the power car of HSR 350x. The result shows better performance.

• 한국정밀공학회지
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• 제32권7호
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• pp.591-595
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• 2015

The roller rig tester for safety performance evaluation of wheel derailment is a test facility which can give the test load condition to the test wheel, similar to the actual dynamic condition in actual running condition. This study describes the evaluation result on the durability of the resilient wheel equipped with the ring damper and the damping material, and installed in the half part of a full scaled bogie in combination with the primary spring when it rotates under the dynamic condition. The evaluation result on durability of resilient wheel after load test of 2 million cycles shows that the safety of wheel is not affected by the applied load in visual inspection and nondestructive test, however, in the bolt used for fastening the ring damper to the wheel the loosening was found. Accordingly the use of self-locking nut and washer is recommended.

• Wind and Structures
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• 제30권4호
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• pp.423-432
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• 2020

A steel high-rise building (HRB) with 15 stories was analyzed under the dynamic load of wind or four different earthquakes taking into consideration the effect of soil-structure interaction (SSI) and using tuned mass damper (TMD) devices to resist these types of dynamic loads. The behavior of the steel HRB as a lightweight structure subjected to dynamic loads is critical especially for wind load with effect maximum at the top of the building and reduced until the base of the building, while on the contrary for seismic load with effect maximum at the base and reduced until the top of the building. The TMDs as a successful passive resistance method against the effect of wind or earthquakes is used to mitigate their effects on the steel high-rise building. Lateral displacements, top accelerations and straining actions were computed to judge the effectiveness of the TMDs on the response of the steel HRB subjected to wind or earthquakes.

• 대한기계학회논문집A
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• 제36권11호
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• pp.1447-1453
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• 2012

도시형 자기부상열차는 U 자형 전자석만을 사용하여 부상공극을 일정하게 유지하며 주행한다. U자형 전자석은 그 형상 특성으로 인하여 전자석 위치에 따라 안내력을 동시에 갖기 때문에 능동적 횡공극 제어가 없이도 차량을 레일에 따라 안내할 수 있는 장점을 갖는다. 그러나 횡공극을 제어하기 않기 때문에 횡진동이 증가하여 승차감 및 주행안정성에 악영향을 미칠 수 있다. 본 논문에서는 능동제어가 없이도 횡진동을 저감시키기 위한 방법으로 횡댐퍼 적용 효과에 대한 분석이 이루어진다. 이를 위하여 자기부상열차의 횡방향 고유진동특성을 우선 해석하고, 횡방향 댐퍼를 설치했을 때의 진동저감 효과 분석이 이루어진다. 정확한 횡진동 예측을 위하여 자기부상열차의 3 차원 다물체 동역학 모델을 사용하였다. 본 논문의 결과를 통해서 자기부상열차의 횡진동 저감을 위한 횡댐퍼 채택 제안에 활용하고자 한다.

• 한국구조물진단유지관리공학회 논문집
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• 제27권6호
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• pp.70-78
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• 2023

보통중심가새골조는 단순한 설계절차를 갖는 이점이 있다. 이와 같은 이유로, 지진하중에 대한 내진성능이 다른 골조 시스템에 비해 크게 효과적이지 않음에도 불구하고 중간 또는 낮은 수준의 지진을 받는 소규모 골조 구조물에 널리 사용되어 왔다. 횡방향 지진 하에서 압축 거동에 대해 취약한 가새부재를 갖는 보통중심가새골조의 내진성능을 향상시키기 위해, 통상적으로 점성감쇠기에 의한 내진보강이 도입되어 왔다. 하지만, 점성감쇠기 자체는 일반적으로 구조물을 원래 위치로 복원시킬 수 있는 강성을 갖지 않는다. 이는 구조물에 잔류 변위를 유발시킬 수도 있다. 이 논문에서는 휨강성을 갖는 상·하부 보가 비선형-탄성 스프링 역할을 하여 외부 변위 이력을 받는 스프링-감쇠기 시스템을 원래 위치로 복원시키는 자가복원형 점성감쇠기 시스템이 개발되었다. 단순화된 골조 구조물에 대한 수치해석은 개발된 자가복원형 점성감쇠기 시스템을 포함할 경우 지진이 가해지는 동안 에너지 소산을 통해 어떻게 골조 구조물의 향상된 내진성능을 가져오는지 보여준다.

• 소음진동
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• 제9권1호
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• pp.174-183
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• 1999

An analytical model for the lateral vibration of beams with a bonded lap joint and partial layered dampers has been proposed in this paper. Both shear and normal forces acting along the interface between the elastic and viscoelastic layers were considered in the vibration analysis. Analytical results were compared with those obtained by a finite element method. Effects of the size and location of layers in partial dampers on system loss factor($\eta_s$) and resonant frequency($\omega_r$) were studied. which showed that partial dampers adhered to the site exhibiting the maximum amplitude of vibration were most influential in the increase of $\eta_s$ and the decrease of $\omega_r$. Specific system loss factor( $\eta_s$ divided by total mass of system) was also evaluated in the analysis.

• Steel and Composite Structures
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• 제20권4호
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• pp.801-812
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• 2016

In an actual design, none of the structures with shear behaviors will be designed for torsional moments. Any failure or damages to roofs, infills, shear walls, and braces caused by an earthquake, will inevitably result in relocation of center of mass and rigidity of the structure. With these changes, the dynamic characteristics of structure could be changed during an earthquake at any moment. The main objective of this paper is to obtain the relationship between time-varying eccentricity of load and corner lateral displacement. In this study, various methods have been used to determine the structural response for time-varying lateral corner displacement. As will be seen below, some of the structural calculation methods result in a significant deviation from the actual results, although these methods include the interaction effects of modes. Controlling the lateral displacement of structure can be performed in different ways such as, passive dampers, friction dampers, semi-active systems including the MR damper and active Systems. Selecting and locating these control systems is very important to bring the maximum safety with minimum cost into the structure. According to this study will be show the relation between the corner lateral displacements of structure and time-varying eccentricity by different kind of methods during an earthquake. This study will show that the response of the structure at the corners due to an earthquake can be very destructive and because of changing the eccentricity of load, calculating the maximum possible response of system can be carried out by this method. Finally, some kind of systems must be used for controlling these displacements. The results shows that, the CQC, DSC and exact methods is comply each other but the results of Vanmark method is not comfortable for these kind of buildings.

• Journal of Electrical Engineering and Technology
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• 제11권6호
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• pp.1787-1792
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• 2016

Previous walking pattern generation methods could generate walking patterns that allow only straight walking on flat and uneven terrain. They were unable to generate modifiable walking patterns whereby the sagittal and lateral step lengths and walking direction can be changed at every footstep. This paper proposes a novel walking pattern generation method to realize modifiable walking of humanoid robots on unknown uneven terrain. The proposed method employs a walking pattern generator based on the 3-D linear inverted pendulum model (LIPM), which enables a humanoid robot to vary its walking patterns at every footstep. A control strategy for walking on unknown uneven terrain is proposed. Virtual spring-damper (VSD) models are used to compensate for the disturbances that occur between the robot and the terrain when the robot walks on uneven terrain with unknown height. In addition, methods for generating the foot and vertical center of mass (COM) of the 3-D LIPM trajectories are developed to realize stable walking on unknown uneven terrain. The proposed method is implemented on a small-sized humanoid robot platform, DARwIn-OP and its effectiveness is demonstrated experimentally.