• Smart Structures and Systems
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• 제26권1호
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• pp.63-75
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• 2020

Substructure pseudo-dynamic hybrid simulation (SPDHS) combining the advantages of physical experiments and numerical simulation has become an important testing method for evaluating the dynamic responses of structures. Various parameter identification methods have been proposed for online model updating. However, if there is large model gap between the assumed numerical models and the real models, the parameter identification methods will cause large prediction errors. This study presents an ANN (artificial neural network) method based on forgetting factor. During the SPDHS of model updating, a dynamic sample window is formed in each loading step with forgetting factor to keep balance between the new samples and historical ones. The effectiveness and anti-noise ability of this method are evaluated by numerical analysis of a six-story frame structure with BRBs (Buckling Restrained Brace). One BRB is simulated in OpenFresco as the experimental substructure, while the rest is modeled in MATLAB. The results show that ANN is able to present more hysteresis behaviors that do not exist in the initial assumed numerical models. It is demonstrated that the proposed method has good adaptability and prediction accuracy of restoring force even under different loading histories.

• 한국산학기술학회논문지
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• 제18권9호
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• pp.68-75
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• 2017

본 논문에서는 해안가의 수평 파력발전 장치에 도입되는 상단 힌지 진자 형태의 파랑에너지 1차 추출 시스템에 대한 동적 운동 특성을 수조에서 모형실험과 연동 시뮬레이션을 통해 고찰 하였다. 조파기의 일정한 파고와 주기의 정현파형태 파도가 수조 프레임에 고정된 상단 힌지 진자 체의 플랩 부이에 부딪쳤을 때 부이 전체의 토크와 운동 궤적을 측정하였다. 또한 파도가 플랩부이에 부딪치는 현상을 강체 동력학과 입자유체 거동에 대한 연동 시뮬레이션을 통해 유체입자가 플랩부이에 부딪칠 때의 압력을 구하여 전체 부이에서의 토크와 힌지에서의 반력을 도출하여 비교 고찰 하였다. 그리고 일 방향수평 파도에 따른 진자 체의 규칙적이고 효과적인 좌우 주기운동을 발생시키기 위한 인장력 조정 값을 도출하였다. 향후 상단 힌지 진자 형태의 에너지 추출장치를 특징으로 하는 해안가 수평파력 발전 장치의 개발 및 제작 시 본 연구에서 도출된 결과 값을 주요 설계 데이터로 적용하고자 한다.

• Earthquakes and Structures
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• 제3권6호
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• pp.821-838
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• 2012

This paper proposes a new three-layer pillar-type hysteretic damper system for residential houses. The proposed vibration control system has braces, upper and lower frames and a damper unit including hysteretic dampers. The proposed vibration control system supplements the weaknesses of the previously proposed post-tensioning vibration control system in the damping efficiency and cumbersomeness of introducing a post-tension. The structural variables employed in the damper design are the stiffness ratio ${\kappa}$, the ductility ratio ${\mu}_a$, and the ratio ${\beta}$ of the damper's shear force to the maximum resistance. The hysteretic dampers are designed so that they exhibit the targeted damping capacity at a specified response amplitude. Element tests of hysteretic dampers are carried out to examine the mechanical property and to compare its restoring-force characteristic with that of the analytical model. Analytical studies using an equivalent linearization method and time-history response analysis are performed to investigate the damping performance of the proposed vibration control system. Free vibration tests using a full-scale model are conducted in order to verify the damping capacity and reliability of the proposed vibration control system. In this paper, the damping capacity of the proposed system is estimated by the logarithmic decrement method for the response amplitudes. The accuracy of the analytical models is evaluated through the comparison of the test results with those of analytical studies.

• Selected Papers of The Society of Naval Architects of Korea
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• 제2권1호
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• pp.29-46
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• 1994

In this paper, the effect of a skirt deformation on the responses of an Air Cushion Vehicle in waves is investigated. The air in the bag and plenum chamber is assumed to be compressible and to have a uniform pressure distribution in each volume. The free surface deformation is determined in the framework of a linear potential theory by replacing the cushion pressure with the pressure patch which is oscillating and translating uniformly. And the bag-finger skirt assumed to be deformed due to the pressure disturbance while its surface area remained constant. The restoring force and moment due to the deformation of bag-finger skirt from equilibrium shape is incorporated with the equations of heave and pitch motions. The numerical results of motion responses due to various ratios of the bag and cushion pressure or bag-to-finger depth ratios are shown.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.34-40
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• 2004

In this paper, peliminary design procedure of magnetorheological (MR) dampers is developed for controlling the building response induced by seismic excitation. Hysteretic biviscous model which is simple and can describe the hysteretic characteristics of MR damper is used for parametric studies. The capacity of MR damper is determined as a portion of not the building weight but the lateral restoring force. A method is proposed for the optimal placement and number of MR dampers, and its effectiveness is verified by comparing it with the simplified search algorithm. Numerical results indicate that the capacity, number and the placement can be reasonably determined using the proposed design procedure.

• Structural Engineering and Mechanics
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• 제21권4호
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• pp.393-406
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• 2005

Cyclic loading tests were carried out on six half-scale reinforced concrete beam-column subassemblages designed to the current Chinese Seismic Design Code for Buildings. The deformation behavior and restoring force characteristics of the subassemblages were studied. Emphasis was directed on their seismic behavior and deformation components. Based on test data and a simplified analysis model of the global and local deformation, the contribution of the deformation components due to beam flexure, column flexure, joint shear, and slippage of longitudinal reinforcement in the joint to the global deformation of subassemblages at different displacement amplitudes of cyclic loading was investigated.

• Structural Monitoring and Maintenance
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• 제3권2호
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• pp.157-174
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• 2016

Based on classical viscoelastic damper, a brand-new damper is designed by the change of simple construction to implement vibration control for both translational vibration and rotational vibration simultaneously. Theoretic analysis has been carried out on the restoring force model and the control parameters. Two improved models are presented to obtain high simulation precision. The influence of the size, shape of the viscoelastic material, the ambient temperature and the response frequency on the vibration control effect is analyzed. The numerical results show that the new type viscoelastic damper is capable of mitigating the multi-dimensional seismic response of offshore platform and the response control effect has complicated relations with aforementioned related factors.

• Structural Engineering and Mechanics
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• 제22권2호
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• pp.241-262
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• 2006

NiTi-wire shape memory alloy (SMA) dampers, that utilize NiTi SMA wires to simultaneously damp tension, compression and torsion, was developed for structural control implementation in this study. First, eight reduced-scale NiTi-wire SMA dampers were constructed. Then tension, compression and torsion experiments using the eight reduced-scale NiTi-wire SMA dampers of different specification were done. The experimental results revealed all of the eight reduced-scale NiTi-wire SMA dampers had the ability to simultaneously supply tension-compression damping and torsion damping. Finally, mechanics analysis of the NiTi-wire SMA dampers was done based on a model of the SMA-wire restoring force and on tension-compression and torsion damping analysis. The damping analytical results were found to be similar to the damping experimental results.

• 한국안광학회지
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• 제9권1호
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• pp.145-159
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• 2004

순목(blinking)에 따른 콘택트 렌즈의 운동을 예측할 수 있는 수학적인 모델과 컴퓨터 수치 해석프로그램을 안검(eyelid)의 가속도, 안검-콘택트 렌즈 사이의 미끄럼 마찰력 등을 고려한 운동(회전) 방정식으로부터 도출하였다. 순목시 안검에 의한 콘택트 렌즈의 운동은 안검이 콘택트 렌즈를 누르는 압력, 순목에 소요되는 시간, 콘택트 렌즈의 직경 등 인자에 영향을 받으며, 프로그램 결과로부터 콘택트 렌즈의 피팅에 중요한 요소인 순목 직후 평형 상태에서 이탈된 콘택트 렌즈의 위치에 대한 예측이 가능하였다. 순목 시간이 짧을수록, 콘택트 렌즈의 직경이 클수록 렌즈의 평형 이탈 거리는 크게 증가하였다. 안검의 압력 증가는 콘택트 렌즈 직경이나 순목 시간에 비해 그 영향은 미미하였다. 순목 후 콘택트 렌즈의 각막위 평형 위치로의 귀환은 순목 시간이 적절한 경우에는 순목 종료 직후의 렌즈 위치에 그다지 영향을 받지 않고 빠르게 이루어지지만 콘택트 렌즈의 직경이 큰 경우에는 렌즈 진동이 급격히 느려지기 때문에 평형 위치로 되돌아오는데 시간이 많이 걸리게 될 것이다. 따라서 직경이 대단히 큰 콘택트 렌즈를 착용한 상태에서 순목 시간이 짧은 경우에는 다음 순목때까지 콘택트 렌즈는 평형 위치에 자리잡지 못하는 결과가 발생하여 순목이 계속됨에 따라 영구 고착 등 현상이 발생할 수도 있을 것이다.

• Steel and Composite Structures
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• 제26권6호
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• pp.719-731
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• 2018

Concrete filled steel tubular (CFST) laced columns have been widely used in high rise buildings in China. Compared to solid-web columns, this type of columns has a larger cross-section with less weight. In this paper, four concrete filled steel tubular laced columns consisting of 4 main steel-concrete tubes were tested under cyclic loading. Hysteresis and failure mechanisms were studied based on the results from the lateral cyclic loading tests. The influence of each design parameter on restoring forces was investigated, including axial compression ratio, slenderness ratio, and the size of lacing tubes. The test results show that all specimens fail in compression-bending-shear and/or compression-bending mode. Overall, the hysteresis curves appear in a full bow shape, indicating that the laced columns have a good seismic performance. The bearing capacity of the columns decreases with the increasing slenderness ratio, while increases with an increasing axial compression ratio. For the columns with a smaller axial compression ratio (< 0.3), their ductility is increased. Furthermore, with the increasing slenderness ratio, the yield displacement increases, the bending failure characteristic is more obvious, and the hysteretic loops become stouter. The results obtained from the numerical analyses were compared with the experimental results. It was found that the numerical analysis results agree well with the experimental results.