• 한국안전학회지
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• 제15권1호
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• pp.1-10
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• 2000

This paper deals with rocking response behavior of rigid block structure subjected to horizontal excitation. A strict consideration of impact and sliding between the block and base is essential to investigate the rocking vibration characteristics because the rocking behavior were greatly influenced by the impact and sliding motion. Therefore, not only restitution coefficient between the block and base but also the energy dissipation rate which is associated with sliding motion, and the static and kinetic friction coefficient between those should be included in the modeling of rocking system. The analytic program was developed to be able to simulate the experimental responses of the block subjected to horizontal sinusoidal excitations. By using this program, rocking responses were numerically calculated by the nonlinear equations for rocking system. From the response simulation and rocking vibration experiment, the following results were obtained. The rocking responses are affected by the impact motion due to energy dissipation and friction and provide very complex behavior. The toppling condition of the block is also influenced by the impact motion and sliding motion.

• Wind and Structures
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• 제29권2호
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• pp.99-110
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• 2019

This paper provides a simple numerical method to determine the optimal parameters of tuned mass damper (TMD) and viscoelastic dampers (VEDs) in frame structure for wind vibration control considering the soil-structure interation (SSI) effect in frequency domain. Firstly, the numerical model of frame structure equipped with TMD and VEDs considering SSI effect is established in frequency domain. Then, the genetic algorithm (GA) is applied to obtain the optimal parameters of VEDs and TMD. The optimization process is demonstrated by a 20-storey frame structure supported by pile group for different soil conditions. Two wind resistant systems are considered in the analysis, the Structure-TMD system and the Structure-TMD-VEDs system. The example proves that this method can quickly determine the optimal parameters of energy dissipation devices compared with the traditional finite element method, thus is practically valuable.

• Earthquakes and Structures
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• 제8권3호
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• pp.699-712
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• 2015

Bracing structures with off-centre bracing system is one of the new resistant systems that frequently used in the frame with pin connections. High ductility, high-energy dissipation and decrease of base shear are advantages of this bracing system. However, beside these advantages, reconstruction and hard repair of off-centre bracing system cause inappropriate performance in the earthquake. Therefore, in this paper, the goal is investigating the behavior of this type of bracing system with ductile element (circular dissipater), in order to providing replacement of damaged member without needing repair or reconstruction of the general system. To achieve this purpose, some numerical studies have been performed using ANSYS software, a frame with off-centre bracing system and optimum eccentricity (OBS-C-O) and another frame with the same identifications without ductile element (OBS) has been created. In order to investigate precisely on the optimum placement of circular elements under monotonic load again three steal frames were modeled. Furthermore, the behavior of this general system investigated for the first time, linear and nonlinear behavior of these two steel frames compared to each other, to achieve the benefit of using the circular element in an off-centre bracing system. Eventually, the analytical results revealed that the performance of steel ring at the end of off-centre braces system illustrating as a first defensive line and buckling fuse in the off-centre bracing system.

• 토지주택연구
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• 제5권2호
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• pp.107-114
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• 2014

수동형 제진장치를 이용하는 제진구조는 수년간 개발이 지속되고 있으며, 1990년대 중반이후로 여러 나라들에서 실무적인 적용이 빠르게 증가되고 있다. 국내의 경우 이러한 제진장치 중 강재이력형 댐퍼가 비교적 저렴한 비용과 설치와 관리가 용이하다는 이유로 건물의 내진설계를 위하여 보편적으로 많이 적용되고 있다. 이 논문에서는 건물의 지진응답을 개선하기 위하여 적용된 소위 카고메댐퍼로 불리우는 등방성 강재이력형 댐퍼(Isotropic Hysteretic Metallic Damper, IHMD)의 유효성에 대한 해석적인 사례연구를 제시하고 있다. 연구대상 건물은 18층 규모의 철근콘크리트 라멘조 아파트건물로 해석결과를 통하여 IHMD의 실효성을 실증적으로 보여주고 있다. 해석결과는 IHMD가 건물의 지진응답을 줄일 수 있는 매우 효과적인 방법임을 검증하고 있다.

• Smart Structures and Systems
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• 제14권6호
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• pp.1031-1054
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• 2014

Real-time hybrid simulation (RTHS) of a stacked wood shear wall retrofitted with a rate-dependent seismic energy dissipation device (viscous damper) was conducted at the newly constructed Structural Engineering Laboratory at the University of Alabama. This paper describes the implementation process of the RTHS focusing on the controller scheme development. An incremental approach was adopted starting from a controller for the conventional slow pseudodynamic hybrid simulation and evolving to the one applicable for RTHS. Both benchmark-scale and full-scale tests are discussed to provide a roadmap for future RTHS implementation at different laboratories and/or on different structural systems. The developed RTHS controller was applied to study the effect of a rate-dependent energy dissipation device on the seismic performance of a multi-story wood shear wall system. The test specimen, setup, program and results are presented with emphasis given to inter-story drift response. At 100% DBE the RTHS showed that the multi-story shear wall with the damper had 32% less inter-story drift and was noticeably less damaged than its un-damped specimen counterpart.

• 한국운동역학회지
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• 제22권3호
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• pp.315-324
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• 2012

The purpose of current study was to investigate the effects of the heights on the lower extremities, torso and neck segments for energy dissipation during single-leg drop landing from different heights. Twenty eight young healthy male subjects(age: $23.21{\pm}1.66yr$, height: $176.03{\pm}4.22cm$, weight: $68.93{\pm}5.36kg$) were participated in this study. The subjects performed the single-leg drop landing from the various height(30, 45 & 60 cm). Force plates and motion-capture system were used to capture ground reaction force and kinematics data, respectively. The results were as follows. First, the ROM at the ankle, knee, hip and trunk was increased with the increased heights but the ROM at the neck was increased in the 60cm. Second, the angular velocity, moment and eccentric work at the ankle, knee, hip, trunk, and neck was increased with the increased heights. Third, the contribution to total work at the knee joint was not significantly different, while the ankle joint rate was decreased and hip and neck rate was increased in the 60cm, and trunk rate was increased with the increased heights. Lastly, the increase in landing height was able to augment the level of energy dissipation not only at the lower extremities but also at the trunk and neck. The findings showed that drop landing affect trunk and neck with lower extremity joints. Therefore, we need to consider that trunk and neck strengthening including stability should be added to reduce sports injury during prevention training.

• 한국강구조학회 논문집
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• 제18권4호
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• pp.457-468
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• 2006

얇은 웨브강판을 사용한 전단지배 강판벽의 최대 에너지소산능력 및 연성능력을 연 구하기 위한 실험 연구를 실시하였다. 이를위해서 얇은 강판을 사용한 3층 골조 강판벽 실험을 수행하였다. 주요 실험 변수는 강판의 형상비와 기둥 단면의 전단강도이며, 골조 강판벽 시스템의 상대적 비교를 위해 중심가새골조 및 모멘트저항골조와의 비교실험을 실시하였다. 골조 강판벽 실험체는 중심가새골조와 모멘트저항골조 실험체에 비하여 매우 우수한 연성도와 에너지소산능력을 나타냈다. 따라서 전단지배형 골조강판벽은 큰 강도, 강성 및 변형능력을 동시에 달성할 수 있는 이상적인 내진구조시스템으로 사용할 수 있다. 전단지배 강판벽의 주기거동을 예측하기 위하여, 본 연구의 실험결과와 기존 실험결과를 토대로 강판벽의 에너지소산능력을 예측할 수 있는 방법을 제시하였다.

• Steel and Composite Structures
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• 제28권3호
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• pp.309-318
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• 2018

Buckling Restrained Braced (BRB) frames have been widely used as an efficient seismic load resisting system in recent years mostly due to their symmetric and stable hysteretic behavior and significant energy dissipation capacity. In this study, to provide a better understanding of the behavior of BRB frames with various beam-column connections, a numerical study using non-linear finite element (FE) analysis is conducted. All models are implemented in the Abaqus software package following an explicit formulation. Initially, the results of the FE model are verified with experimental data. Then, diverse beam-column connections are modeled for the sake of comparison from the shear capacity, energy dissipation and frame hysteresis behavior points of view until appropriate performance is assessed. The considered connections are divided into three different categories: (1) simple beam-column connections including connection by web angle and connection by seat angle; (2) semi-rigid connection including connection by web and seat angles; and (3) rigid beam-column connections by upper-lower beam plates and beam connections with web and flange splices. Results of the non-linear FE analyses show that these types of beam-column connections have little effect on the maximum story drift and shear capacity of BRB frames. However, the connection type has a significant effect on the amount of energy dissipation and hysteresis behavior of BRB frames. Also, changes in length and thickness of the angles in simple and semi-rigid connections and changes in length and thickness of plates in rigid connections have slight effects (less than 4%) on the overall frame behavior.

• Earthquakes and Structures
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• 제11권1호
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• pp.165-178
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• 2016

The goal of energy-based seismic design is to obtain a structural design with a higher energy dissipation capacity than the energy dissipation demands incurred under earthquake motions. Accurate estimation of the story hysteretic energy demand of a multi-story structure is the key to meeting this goal. Based on the assumption of a mode-equivalent single-degree-of-freedom system, the energy equilibrium relationship of a multi-story structure under seismic action is transformed into that of a multi-mode analysis of several single degree-of-freedom systems. A simplified equation for the estimation of the story seismic hysteretic energy demand was then derived according to the story shear force and deformation of multi-story buildings, and the deformation and energy relationships between the mode-equivalent single-degree-of-freedom system and the original structure. Sites were categorized into three types based on soil hardness, namely, hard soil, intermediate hard (soft) soil, and soft soil. For each site type, a 5-story and 10-story reinforced concrete frame structure were designed and employed as calculation examples. Fifty-six earthquake acceleration records were used as horizontal excitations to validate the accuracy of the proposed method. The results verify the following. (1) The distribution of seismic hysteretic energy along the stories demonstrate a degree of regularity. (2) For the low rise buildings, use of only the first mode shape provides reasonably accurate results, whereas, for the medium or high rise buildings, several mode shapes should be included and superposed to achieve high precision. (3) The estimated hysteretic energy distribution of bottom stories tends to be underestimated, which should be modified in actual applications.

• International Journal of Air-Conditioning and Refrigeration
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• 제10권1호
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• pp.19-30
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• 2002

This paper addresses characteristics of compressible flow dynamics inside a pipe with an accumulator and an inlet orifice. It also presents a simple but stable numerical method associated with the accumulator-orifice calculation. In particular, a focus is given to developing a method of finding an optimum design of the accumulator-orifice system (i.e., the accumulator size and the throttle resistance) that gives the most effective dissipation of the water-hammering problem. It is found that there exists indeed an optimum set of parameter values for the most effective dissipation of the wave energy.