• 제목/요약/키워드: structural vibration

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A study on the estimation of an equivalent system of a local vibration system of a huge structure and the Optimum Structural Modification Method (거대 구조물의 국부진동계의 등가계 산출과 이를 이용한 최적구조변경법)

  • 황문주;박석주;이기문
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 한국소음진동공학회 1997년도 추계학술대회논문집; 한국과학기술회관; 6 Nov. 1997
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    • pp.364-369
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    • 1997
  • It is very difficult to execute the vibration analysis of a huge structure, which takes up much time and expense. In this paper we intend to make the equivalent system of a local vibration system of a huge structure with a view to improving the dynamic characteristics and reducing time and expense. First of all, upper deck structure model is maded. And we perform the vibration analysis by the Substructure Synthesis Method and execute the exciting test for the upper deck structure model, and observe the coincidences of two results to confirm the reliability of the analyzing tools used. To make the equivalent system, we give boundary condition to sub-structure that want to be modified and execute the Sensitivity Analysis Method and the Optimum Structural Modification Method. And we execute the structural modification of the equivalent system.

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Active Structural Vibration Control using Forecasting Control Method (예측 제어기법을 이용한 기계 구주물의 능동 진동제어)

  • 황요하
    • Journal of KSNVE
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    • 제2권4호
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    • pp.293-304
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    • 1992
  • Active vibration control is presented with simulation and experiment. Dynamic Data System(DDS) method is used for system modeling and this model is combined with an forecasting control technique to derive a control equation. In the experiment, on-line digital computer monitors structural vibration and calculates control input. The control input is sent to an electromagnetic actuator which cancels the structural vibration. Experiment is performed first with a simple beam setup to demonstrate the effetiveness of this method. This method is then applied to a color laser printer to actively modify the structure. The beam experiment showed vibration reduction of over 60% with one-and two-DOF models. In the printer structure experiment, the first mode of 308 Hz was successfully controlled with a one-DOF model.

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Vibration Control on the Diesel Power Plant by the Phase Adjustment of Parallel Engines' X-mode Vibration (병렬 엔진의 X형 진동 위상조정에 의한 디젤 발전플랜트 진동제어)

  • 이돈출;이병운;김용근;전효중
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 한국소음진동공학회 1996년도 춘계학술대회논문집; 부산수산대학교, 10 May 1996
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    • pp.221-226
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    • 1996
  • Structural vibrations of adjacent buildings, manufacturing factories and engines on the stationary diesel power plant were increased by the variation of phase angle between two engines sometimes. In this paper, top bracings and synchrophaser have been introduced in order to reduce these vibrations. As a result, all of structural vibrations were greatly improved by the phase adjustment of 6th order X-mode vibration with these.

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Structural Vibration Control Technique using Modified Probabilistic Neural Network

  • Chang, Seong-Kyu;Kim, Doo-Kie
    • Journal of the Computational Structural Engineering Institute of Korea
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    • 제23권6호
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    • pp.667-673
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    • 2010
  • Recently, structures are becoming longer and higher because of the developments of new materials and construction techniques. However, such modern structures are more susceptible to excessive structural vibrations which cause deterioration in serviceability and structural safety. A modified probabilistic neural network(MPNN) approach is proposed to reduce the structural vibration. In this study, the global probability density function(PDF) of MPNN is reflected by summing the heterogeneous local PDFs automatically determined in the individual standard deviation of each variable. The proposed algorithm is applied for the vibration control of a three-story shear building model under Northridge earthquake. When the control results of the MPNN are compared with those of conventional PNN to verify the control performance, the MPNN controller proves to be more effective than PNN methods in decreasing the structural responses.

An Experimental Study on the Vertical Vibration Transfer according to Shear Wall Building Structures due to Exciting Vibration Forces (전단벽식 건축구조물의 수직진동 전달특성에 관한 실험연구)

  • Chun Ho-Min
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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    • pp.159-166
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    • 2005
  • The vibration on building structures due to exciting vibration forces has been studied only for the vibration level on existing buildings. Recently, several researches have been performed on the prediction of vertical vibration on structures by using an analytical method. However, these studies have been focused on mainly the vibration analysis through analytical modeling of structures. This study aims to investigate the characteristics of vertical vibration transfer in terms of the directions of transfer(upward transfer and downward transfer) on the shear wall building structures due to 2 type vibration forces. In order to examine the characteristics of vertical vibration transfer, the mode analysis and the impact experiment were conducted several times on one building structure. The results of this study suggest that the characteristics of vertical vibration transfer are different in terms of the directions of transfer.

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Vibration Velocity Response of Buried Gas Pipelines according to Train Speed (지중 매설 가스 배관의 열차 주행 속도에 따른 진동 속도 특성)

  • Kim, Mi-Seung;Sun, Jin-Sun;Kim, Gun;Kim, Moon-Kyum
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 한국전산구조공학회 2008년도 정기 학술대회
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    • pp.561-566
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    • 2008
  • Recently, because of development of the high speed train technology, the vibration loads by train is significantly increased ever than before. This buried gas pipelines are exposed to both repeated impact loads, and, moreover, they have been influencing by vibration loads than pipeline which is not located under vehicle loads. The vibration characteristic of pipeline is examined by dynamic analysis, and variable is only train speed. Since an effect of magnitude of vibration loads is more critical than cover depth, as increasing the train speed, the vibration speed of buried pipelines is also increased. The slope of vibration velocity is changed by attenuation of wave, at train speed, 300 km/h. From the analysis results, the vibration velocity of pipelines is satisfied with the vibration velocity criteria which are established by Korea Gas Corporation. The results present operation condition of pipelines under rail loads has fully sound integrity based on KOGAS specification.

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Characteristics of Vertical Vibration Transfer according to RC Structure Systems (RC조 건축물의 구조시스템에 따른 수직진동 전달 특성 비교)

  • Chun, Ho-Min
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 한국소음진동공학회 2006년도 추계학술대회논문집
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    • pp.196-201
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    • 2006
  • In general, the vertical vibration problems for strength of members and serviceability of building structures are not considered in structural design process, but the prediction of the vertical vibration is very important and essential to structural design process. This study aims to investigate the characteristics of vertical vibration in terms of the transfer of horizontal directions on the rahmen building structures and the shear wall building structures. In order to examine the characteristics of vertical vibration, the modal test and the heel-drop excitation experiments were conducted several times on the two type building structures. The results from the experiments are analyzed and compared with the results. The results of this study suggest that the characteristics of vortical vibration transfer in horizontal way are effected from the fundamental frequency of the slabs and excitation forces and are effected the shear wall on the path of the vibration transfer.

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Prediction and analysis of structural noise of a box girder using hybrid FE-SEA method

  • Luo, Wen-jun;Zhang, Zi-zheng;Wu, Bao-you;Xu, Chang-jie;Yang, Peng-qi
    • Structural Engineering and Mechanics
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    • 제75권4호
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    • pp.507-518
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    • 2020
  • With the rapid development of rail transit, rail transit noise needs to be paid more and more attention. In order to accurately and effectively analyze the characteristics of low-frequency noise, a prediction model of vibration of box girder was established based on the hybrid FE-SEA method. When the train speed is 140 km/h, 200 km/h and 250 km/h, the vibration and noise of the box girder induced by the vertical wheel-rail interaction in the frequency range of 20-500 Hz are analyzed. Detailed analysis of the energy level, sound pressure contribution, modal analysis and vibration loss power of each slab at the operating speed of 140 km /h. The results show that: (1) When the train runs at a speed of 140km/h, the roof contributes more to the sound pressure at the far sound field point. Analyzing the frequency range from 20 to 500 Hz: The top plate plays a very important role in controlling sound pressure, contributing up to 70% of the sound pressure at peak frequencies. (2) When the train is traveling at various speeds, the maximum amplitude of structural vibration and noise generated by the viaduct occurs at 50 Hz. The vibration acceleration of the box beam at the far field point and near field point is mainly concentrated in the frequency range of 31.5-100 Hz, which is consistent with the dominant frequency band of wheel-rail force. Therefore, the main frequency of reducing the vibration and noise of the box beam is 31.5-100 Hz. (3) The vibration energy level and sound pressure level of the box bridge at different speeds are basically the same. The laws of vibration energy and sound pressure follow the rules below: web

Evaluate of allowable acceleration for Occupants in Horizontal Vibration of Buildings according to Natural Frequency (고유주기에 따른 건축물의 수평진동에 대한 거주자의 허용가속도평가)

  • Cho, Kang-Pyo;Jeong, Seung-Hwan;Cho, Gi-Sung
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 한국전산구조공학회 2008년도 정기 학술대회
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    • pp.228-233
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    • 2008
  • In this paper, peak acceleration for horizontal vibration of buildings was estimated from the results of vibration tests using a shaking table. Human comfort of occupants is supposed to be satisfied according to the peak acceleration in NBCC and ISO6897, which have been used by Korean structural engineers. In the paper, we used a one-dimensional shaking table for horizontal vibration tests, which was mounted with a vibration house similar to a living space. Experimental results were obtained according to increasing accelerations in the range of 0.2Hz through 1.2Hz of frequency with five experimental groups, each of which was composed of eight persons. We obtained performance curves by dividing the distribution of perception from horizontal vibration tests into the ranges of 0${\sim}$25%, 26${\sim}$50%, 51${\sim}$75%, 76${\sim}$100% and then fitting the curves. Also we made a questionnaire based on human comfort criteria of foreign countries, and examined the feelings of subjects. From the results of horizontal vibration tests, it was found that acceleration of perception was low when frequency was high, and that visual and auditory senses affect the human perception for horizontal vibration of buildings.

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Structural Vibration Control for Broadband Noise Attenuation in Enclosures

  • Krishnaswamy Kailash;Rajamani Rajesh;Woo Jong Jin;Cho Young Man
    • Journal of Mechanical Science and Technology
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    • 제19권7호
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    • pp.1414-1423
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    • 2005
  • This paper develops and evaluates several strategies for structural vibration control with the objective of attenuating broadband noise inside a rectangular enclosure. The strategies evaluated include model-independent collocated control, model-based feedback control and a new 'modal-estimate' feedback strategy. Collocated control requires no knowledge of model parameters and enjoys the advantage of robustness. However, effective broadband noise attenuation with colocated control requires a large number of sensor-actuator pairs. Model-based con-trollers, on the other hand, can be theoretically effective even with the use of a single actuator. However, they suffer from a lack of robustness and are unsuitable from a practical point of view for broadband structural vibration applications where the dynamic models are of large order and poorly known. A new control strategy is developed based on attenuating a few structural vibration modes that have the best coupling with the enclosure acoustics. Broadband attenuation of these important modes can be achieved using a single actuator, a limited number of accelerometers and limited knowledge of a few modal functions. Simulation results are presented to demonstrate the effectiveness of the developed strategy.