• Title/Summary/Keyword: 단변분 탐색법

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Numerical Model Updating Based on Univariate Search Method for High Speed Railway Bridges (단변분 탐색법에 기초한 고속철도교량의 수치해석 모델 개선)

  • Park, Dong-Uk;Kim, Nam-Sik;Kim, Sung-Il
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.1
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    • pp.17-27
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    • 2014
  • Numerical model became one of most important tools for identifying the state of an existing structure in accordance with development of numerical analysis techniques. A numerical model should be updated based on the measured responses from the existing structure to accurately use the model for identifying the state of the bridge and executing numerical experiments. In this study, a new model updating method based on repetition method without a differential function is introduced and applicability for high speed railway bridge is verified with dynamic stability analysis. A fine measurement based on measurement points roaming method was executed with an wireless measurement system for precise dynamic characteristic analysis. The natural frequencies and mode shapes were estimated by correlation analysis and a mode decomposition technique. An initial numerical model was constructed based on design drawings and the model have been updated in accordance with the introduced model updating method. The results from numerical experiment and field test have been compared for verifying the applicability of the model updating method. And the dynamic stability analysis has been executed to verify the usability of the updated numerical model and the model updating method. It seems that the model updating method can be used for various bridges after evaluation of applicability for other type bridges in further studies.

Back Analysis Technique for the Estimation of Tension Force on Hanger Cables (역해석기법을 이용한 행어케이블의 장력 추정)

  • Kim, Nam-Sik;Park, Dong-Uk;Park, Yong-Myung;Cheung, Jin-Hwan
    • Journal of the Earthquake Engineering Society of Korea
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    • v.11 no.3 s.55
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    • pp.1-10
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    • 2007
  • In general, the tension forces of hanger cable in suspension bridges play an important role in evaluating the bridge conditions. The vibration method, as a conventional one, has been widely applied to estimate the tension forces by using the measured frequencies on hanger cables. However, the vibration method is not applicable to short hanger cables because the fiequencies of short cables are severely sensitive to flexural rigidity. Thus, in this study, the tension forces of short hanger cables, of which the length is shorter than 10 meters, were estimated through back analysis of the cable fiequencies measured from Gwang-An suspension bridge in Korea. Direct approach to back analysis is adopted using the univariate method among the direct search methods as an optimization technique. The univariate method is able to search the optimal tension forces without regard to the initial ones and has a rapid convergence rate. To verify the feasibility of back analysis, the results from back analysis and vibration method are compared with the design tension forces. From the comparison, it can be inferred that back analysis results are more reasonable agreement with the design tension forces of short hanger cable. Therefore, it is concluded that back analysis applied in this study is an appropriate tool for estimating tension forces of short hanger cables.