• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.4
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• pp.649-659
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• 1999

본 연구에서는 점탄성감쇠기가 설치된 비비례 감쇠 구조물의 바람에 대한 확률적 응답을 진동수영역에서 구하였다. 복소수 고유치 및 고유백터를 바탕으로 모드중첩법을 이용하여 응답의 RMS 값을 구하고 그것을 근사적인 방법인 모드 변형에너지법에서 얻은 결과와 비교하였다. 또한, 가력 진동수에 따라서 변하는 점탄성감쇠기의 강성 및 감쇠 계수를 상수로 모형화하였을 때의 풍응답 해석 결과의 정확성을 진동수영역에서 검증하였다. 해석결과에 의하면 감쇠기의 진동수 의존 특성은 구조물의 1차 고유 진동수에 의해서 비교적 정확하게 표현되었고, 모드 변형에너지법은 대체로 정확한 결과를 도출하였지만, 가속도 응답을 구할 때에는 다소 큰 오차를 유발하였다.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.439-442
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• 2002

In this study, a turbulence simulation is carried out in a suction type wind tunnel using grids, where turbulent flows with various turbulence intensity are successfully produced by the change of grid size, arrangement of grids and settling position, respectively. Response tests of rectangular cylinder models with aspect ratio of 2 and 4 are carried out in smooth flow and generated turbulent flows. Additionally, two types of fairing are considered such as right triangle and regular triangle. The effects of wind velocity fluctuations and fairing are discussed on vortex-induced oscillation.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.340-343
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• 2011

장대 케이블 교량의 풍응답을 계측할 수 있는 무선센서네트워크 기반의 풍응답 계측시스템을 개발하고, 이를 사용하여 인천대교의 시공단계별로 고유진동수, Mode Shape과 같은 Modal Parameters의 변화를 추정하고 보강형에서의 풍압분포와 보강형, 주탑, 케이블의 가속도를 계측하여 내풍 성능을 분석하였다. 개발된 계측 시스템은 인천대교 사장교의 전체 거동을 계측할 수 있도록, 1.5km 범위에 넓게 분포된 최대 55 Nodes에서 최대 1kHz의 동기화된 계측을 수행할 수 있으며, 각 Node별로 3축가속도나 풍압을 측정할 수 있다. 전체 Node에서 가속도를 계측하는 경우에는 최대 165 Channel을 1kHz로 측정할 수 있다. Modal 해석의 경우에, 고가교, 접속교, 사장교 주탑, 보강형, 케이블의 시공 단계별 동특성의 변화를 추정하였으며, 고가교에서는 모드해석을 통해 역추정한 구조계수를 정적재하실험 및 실험실에서의 Mold 시험결과와 비교하였으며 사장교 케이블에서는 케이블 댐퍼의 성능을 분석하였다. 또한 인천대교 보강형에서의 풍압분포를 계측하였으며, 풍압의 공간상관관계를 분석하였고, 풍하중 및 풍진동 특성을 분석하여 가속도 계측 결과와 비교하였다. 계측 및 분석 결과를 바탕으로 장대교량의 내풍성능을 확보하고 향상시키는데 활용할 수 있을 것으로 기대한다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.1
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• pp.1-7
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• 2020

The wind responses of twin buildings are determined by the characteristics of wind loads and the dynamic characteristics of the structural systems of the buildings. In this study, the characteristics of wind pressure that influence wind responses were identified for two different spacings between the twin buildings using a wind tunnel test and the proper orthogonal decomposition (POD) method. Structural dynamic characteristics were also identified using 3D structural system modeling. The double modal transformation method was utilized to evaluate the characteristics of wind pressure for across-wind and along-wind conditions and the effect of the dynamic characteristics of each structure on the wind responses. The channeling and vortex effects were identified through the POD method. Across-wind loads were significantly affected by the spacings between the twin buildings, whereas along-wind loads were minimally affected. Similarly, while using the double modal transformation method, a significant difference was noticed in case of the cross-participation coefficients in the across-wind direction condition for the different spacings between the buildings; however, the along-wind direction condition showed negligible difference. Therefore, the spacing between the two buildings plays a more important role in across-wind responses compared to along-wind responses.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.7 s.124
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• pp.649-661
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• 2007

Friction-type reinforcing members(FRM) to enhance the resistance to wind loads of a transmission tower through both stiffness strengthening and damping increase are energy dissipation devices that utilize bending deflection of a tower leg. In this paper, the hysteretic behavior of the transmission tower structure with FRMs was experimentally investigated through cyclic loading tests on a half scale substructure model. Firstly, the variation of friction forces and durability of the FRM depending on the type of friction-inducing materials used in the FRM were examined by performing the cyclic loading tests on the FRM. Secondly, cyclic loading tests of a half-scale two-dimensional substructure model of a transmission tower with FRMs were conducted. Test results show that the FRM, of which desired maximum friction force is easily regulated by adjusting the amplitude of the torque applied to the bolts, have stable hysteretic behaviors and it is found that there exists the optimum torque depending on a design load by investigating the amount of energy dissipation of the FRMs according to the increase of torque.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.4 s.74
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• pp.369-374
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• 2006

This paper describes dynamic characteristics of a power transmission tower consisting of lots of power lines and insulators. A numerical 3D modeling for the static, dynamic and buckling analyses of the power transmission tower is presented considering the case when the power lines are cut. Eigenvalue analysis indicates that the transmission tower shows different behavior comparing to usual structures governed by several low modes. The transmission tower is governed by lots of modes. It is verified that the transmission tower is structurally safe against the static wind and buckling loads. But the structural and buckling safety is not guaranteed when all power lines are cut, which comes to collapse the transmission tower. Further study is in need to overcome such case. Wind dynamic analysis shows that fluctuating wind loads increase the response of the tower.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.6
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• pp.309-314
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• 2018

The wind load and structural characteristics of a twin building are more complex than those of conventional high-rise buildings. The pressure load due to wind on a twin building was therefore measured via wind tunnel experiments to analyze such characteristics. The wind pressure pattern was then deduced from measured data using proper orthogonal decomposition. Channeling and vortex shedding were observed in the first and second modes, respectively. The along-wind loads on the two buildings featured a positive correlation and the cross-wind loads featured no correlation. Such a correlation affected the wind-induced displacement. The structural member connecting the two buildings had an insignificant effect on the positive correlation, but it notably reduced the wind-induced displacement with a negative correlation.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.4
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• pp.223-230
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• 2014

In this paper, the wind-induced response characteristics of freeform shaped tall building is studied by using FSI analysis. The analytical models are twist shaped ones at representing type of atypical tall building, and this study focused on the relationship between twist angle and wind acceleration. Firstly, 1-way FSI analysis is performed, so maximum lateral displacement of the analytical model for 100 years return period wind speed is calculated, then the elastic modulus of a structure that satisfies the constraints condition is evaluated. And 2-way FSI analysis is carried out. so acceleration of the analytical model for the evaluated modulus of elasticity and arbitrary density is predicted through time history analysis. The basic model is a set of a square shape, height is 400m, slenderness ratio is 8, and twist model is rotated at square model from 0 to 90 degrees at intervals of 15 degrees and from 90 to 360 degrees at intervals of 90 degrees. According to the result of predicting wind acceleration by the shape of each model, the wind vibration effect of square shape model is confirmed to be sensitive more than a twist shape ones.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.598-601
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• 2011

동적응답과 하중을 정확히 산정하기 위해서는 구조물의 동적특성을 정확히 평가하는 것이 중요하기 때문에, 현재 대부분의 경우 FE 모델을 이용한 Modal 해석을 dldydg하여 동특성을 평가하고 있다. 그러나 실제 건물의 계측결과와 동적특성의 해석결과가 많은 차이를 나타내고 있으므로 해석결과의 신뢰성을 향상하기 위해서는 FE 모델에 대한 Calibration이 수행될 필요성이 있다. 이 논문에서는 초고층, 아파트, 대공간 구조물에 대한 계측을 수행하고 이 결과를 바탕으로 동특성을 정확히 예측하기 위한 FE 모델의Calibration 과정을 제시하였다. 이 결과를 바탕으로 동적특성의 정확성이 풍동실험결과의 신뢰성에 미치는 영향을 분석하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.6
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• pp.769-778
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• 2007

In this paper, excitation systems using linear mass shaker (LMS) and active tuned mass damper (ATMD) are presented in order to simulate the wind induced responses of a building structure. The actuator force for the excitation systems is calculated by using the inverse transfer function of a target structural response to the actuator. Filter and envelop function are used such that the error between the wind and actuator induced responses is minimized by preventing the actuator from exciting unexpected modal response and initial transient response. The analyses results from a 76-story benchmark building problem in which wind load obtained by wind tunnel test is given, indicate that the excitation system installed at a specific floor can approximately embody the structural responses induced by the wind load applied to each floor of the structure. The excitation system designed by the proposed method can be effectively used for evaluating the wind response characteristics of a practical building structure and for obtaining an accurate analytical model of the building under wind load.