• Smart Structures and Systems
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• 제19권1호
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• pp.11-20
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• 2017

For structural damage detection of shear buildings, this paper proposes a new concept using structural element mass-stiffness vector (SEMV) based on special mass and stiffness distribution characteristics. A corresponding damage identification method is developed combining the SEMV with the cross-model cross-mode (CMCM) model updating algorithm. For a shear building, a model is assumed at the beginning based on the building's distribution characteristics. The model is updated into two models corresponding to the healthy and damaged conditions, respectively, using the CMCM method according to the modal parameters of actual structure identified from the measured acceleration signals. Subsequently, the structural SEMV for each condition can be calculated from the updated model using the corresponding stiffness and mass correction factors, and then is utilized to form a new feature vector in which each element is calculated by dividing one element of SEMV in health condition by the corresponding element of SEMV in damage condition. Thus this vector can be viewed as a damage detection feature for its ability to identify the mass or stiffness variation between the healthy and damaged conditions. Finally, a numerical simulation and the laboratory experimental data from a test-bed structure at the Los Alamos National Laboratory were analyzed to verify the effectiveness and reliability of the proposed method. Both simulated and experimental results show that the proposed approach is able to detect the presence of structural mass and stiffness variation and to quantify the level of such changes.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.37-44
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• 2003

In this proposed work, computational, finite element model far multi-delaminated plates will be developed. In the current analysis procedures of multi-delaminated plates, different elements are used at delaminated and undelaminated region separately. In the undelaminated region, plate element based on Mindlin plate theory is used in order to obtain accurate results of out-of-plane displacement of thick plate. And for delaminated region, plate element based on Kirchhoff plate theory is considered. To satisfy the displacement continuity conditions, displacement vector based on Kirchhoff theory is transformed to displacement of transition element. Element mass and stiffness matrices of each region (delaminated, undelaminated and transition region) will be assembled for global matrix.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1260-1265
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• 2001

It is important to model the mechanical structure precisely and reasonably in predicting the dynamic characteristics, controlling the vibration, and designing the structural dynamics. In the finite element modeling, the errors can be contained from the physical parameters, the approximation of the boundary conditions, and the element modeling, From the dynamic test. more precise dynamic characteristics can be obtained. Model updating using parameter modification is appropriate when the design parameter is used to analyze the input parameter like finite element method. Finite element analysis for free-free-free-free(FFFF) and clamped-free-free-free(CFFF) plate with uniform area and shape change are carried out as model updating examples, Mass and stiffness matrices are updated by comparing test and analytical modal frequencies. The result shows that the updated frequencies become closer to the test frequencies.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.939-948
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• 2006

The structural anisotropy and heterogeneity of rock mass, caused by discontinuities and weak zones, have a great influence on the deformation behavior of tunnel. Tunnel construction in these complex ground conditions is very difficult. No matter how excellent a geological investigation is, local uncertainties of rock mass conditions still remain. Under these uncertain circumstances, an accurate forecast of the ground conditions ahead of the advancing tunnel face is indispensable to safe and economic tunnel construction. This paper presents the effect of anisotropy and heterogeneity of the rock masses to be excavated by numerical analysis. The influences of distance from weak zone, the size or dimension, the different stiffness and the orientation of weak zones are analysedby 2-D and 3-D finite element analysis. By analysing these numerical results, the tunnel behavior due to excavation can be well understood and the prediction of rock mass condition ahead of tunnel face can be possible.

• 한국터널지하공간학회 논문집
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• 제8권2호
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• pp.115-128
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• 2006

불연속면 또는 연약대로 인해 야기되는 암반의 구조적 이방성과 비균질성은 터널의 변형 거동에 큰 영향을 미친다. 아무리 우수한 지반조사가 이루어진다 하더라도, 지역적 불확실성은 여전히 남아 있으므로 복잡한 지반 조건에서의 터널 굴착은 매우 어려운 작업이다. 이러한 불확실한 환경에서 터널 막장 전방의 지반 상태를 정확히 예측하는 것은 안전하고 경제적인 터널 건설에 필요불가결하다 할 수 있다. 따라서 본 논문은 3차원 수치해석을 통하여 암반의 이방성 및 비균질성의 영향을 평가하였다. 즉 터널 굴착으로 인해 야기되는 지반 거동을 분석하고 이에 대한 연약대의 폭과 강성 그리고 방향성의 영향을 정량적으로 평가하였다.