• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.857-864
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• 2006

Due to the difficulties in numerical generation of random fields that satisfy not only the probabilistic distribution but the spectral characteristics as well. it is relatively hard to find an exact response variability of a structural response with a specific random field which has its features in the spatial and spectral domains. In this study. focusing on the fact that the random field assumes a constant over the domain under consideration when the correlation distance tends to infinity, a semi-theoretical solution of response variability is proposed for in-plane and plate bending structures. In this procedure, the probability density function is used directly resulting in a semi-exact solution for the random field in the state of random variable. It is particularly noteworthy that the proposed methodology provides response variability for virtually any type of probability density functions.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.644-647
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• 2011

지형 및 환경에 따라 해안 사면의 침식, 세굴을 막기 위한 효과 있는 해안구조물의 설치가 필요하다. 본 연구에서는 유체-구조 상호작용을 고려해서 유한요소해석 프로그램인 LS-DYNA를 사용하여 조파 실험모델링을 하고, 해안사석구조물과 상호작용에 의한 유체 흐름을 분석하였다. 사석의 유무와 크기, 개수 등의 변수를 조정하여 서로 다른 4가지 경우에 따른 결과를 비교 분석하였다. 또한 해안사석구조물을 구성하는 투수 콘크리트의 특성 분석을 위하여 CT 이미지를 사용하여 투수 콘크리트의 공극 분포를 관찰하였다. 투수 콘크리트의 특성에 큰 영향을 미치는 공극 분포의 파악을 위하여 확률 분포 함수를 사용하여 투수 콘크리트 공극의 공간적 분포를 분석하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.04a
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• pp.173-181
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• 1996

In this study, a stochastic finite element model is proposed with a view to consider the uncertainty of physical properties of rock mass in the analysis of structural behavior on underground caverns. Here, the Latin Hypercube Sampling technique, in which can makeup weak points of the Monte Carlo Simulation, is applied for the analysis of underground cavern. The validity of the newly developed computer program has been confirmed in terms of verification examples. And, the applicability of the program to the field has been tested in terms of the analysis of the underground oil storage cavern in korea.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2023.11a
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• pp.303-304
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• 2023

확률론적 위험성 평가는 하중, 재료특성 등과 같은 불확실성 인자를 고려하여 구조물의 안전성을 평가하는 기법이지만 모든 불확실성을 고려하는 것은 현실적으로 불가능하다. 또한 원전 격납건물은 콘크리트, 철근, 라이너, 텐던이 복잡하게 결합되어 있다. 따라서 전역민감도 분석을 통해 격납건물의 불확실성 인자 검토하고 선정하는 작업은 필요하다. 따라서 본 연구는 대리모델을 기반으로 축소규모 원전 격납건물의 전역 민감도 분석을 수행하고 격납건물의 주요 영향인자를 분석하고자 한다. 유한요소 해석 모델을 기반으로 대리모델의 학습데이터를 생성하였으며 구축된 대리모델의 성능지표를 분석하였을 때 높은 회귀성능을 갖는 것으로 판단된다. 대리모델을 기반으로 전역 민감도 분석을 수행한 결과 콘크리트의 인장균열이 발생하는 내압수준에서 민감도 지수는 콘크리트의 압축강도가 높지만, 전체적인 내압 구간에서 민감도 지수는 텐던의 탄성계수 및 항복강도가 높은 것으로 나타났다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.10a
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• pp.95-102
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• 1996

In this study, a stochastic finite element model is proposed with a view to consider the uncertainty of physical properties of discontinuous rock mass in the analysis of structural behavior on underground caverns. In so doing, the LHS(Latin Hypercube sampling) technique has been applied to make up weak points of the Crude Monte Carlo technique. Concerning the effect of discontinuities, a joint finite element model is used that is known to be superior in explaining faults, cleavage, things of that nature. To reflect the uncertainty of material properties, the variables such as the the elastic modulus, the poisson's ratio, the joint shear stiffness, and the joint normal stiffness have been used, all of which can be applicable through normal distribution, log-normal distribution, and rectangulary uniform distribution. The validity of the newly developed computer program has been confirmed in terms of verification examples. And, the applicability of the program has been tested in terms of the analysis of the circular cavern in discontinuous rock mass.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1989.10a
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• pp.40-45
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• 1989

In order to take account of the statistical properties of random variables used in the structural analysis, the conventional approach usually adopts the safety factor based on past experiences for the qualitative assessment of structural safety problem. Recently, new approach based on the probabilistic concept has been applied to the assessment of structural safety in order to circumvent the difficulties of the conventional approach in choosing the appropriate safety factor. Thus, computer program called "Probabilistic finite element method" is developed by incorporation the probabilistic concept into the conventional matrix method in order to investigate the effects of the random variables on the final output of the structural analysis. From the comparison of some examples, it can be concluded that the PFEM developed in this study deals with consistently with the uncertainty of random variables and provides the rational tool for the assessment of structural safety of plane frame.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1993.04a
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• pp.117-124
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• 1993

The Neumann Expansion method has been used for evaluating the response variability of three dimensional truss structure resulting from the spatial variability of material properties with the aid of the finite element method, and in conjunction with the direct Monte Carlo simulation methods. The spatial variabilites are modeled as three-dimensional stochastic field. Yamazaki 〔1〕 has extended the Neumann Expansion method to the plane-strain problem to obtain the response variability of 2 dimensional stochastic systems. This paper presents the extension of the Neumann Expansion method to 3 dimensional stochastic systems. The results by the NEM are compared with those by the deterministic finite element analysis and by the direct Monte Carlo simulation method

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.200-202
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• 1999

A method of stochastic finite element analysis is developed for yield a uncertainty of engineering problems. Where, a stochastic finite-element method for shapes modeling is proposed a6 a means to solve the models with the uncertainty and variety. This method is based on the probability and illustrated by a first-Order Second-Moment Method and considering the covariance of random variables. The validity and accuracy of the stochastic finite element method is verified through comparing with those solved by the conventional 2-D finite element method.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.365-372
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• 2003

In this study, the program which determine the initial cable tension force by tile initial shape analysis for cable stayed bridge is developed. Also, DSFEMP(Dynamic Stochastic Finite Element Analysis Program) is developed to consider the variance of random variables at each step of dynamic response analysis, not use existing methods that apply to the theory of reliability at the final step of structural analysis. In addition, the output from the developed program was compared with the results from DMCSP(Direct Monte Carlo Simulation Program) to prove its validity.

• Journal of the Korea Concrete Institute
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• v.22 no.1
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• pp.77-84
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• 2010

Latex modified concrete (LMC) exhibits improved material properties including high tensile strength and durability compared with conventional concrete, and hence LMC has been used as protective layers over the bridge deck slabs to increase their service life with underlying assumption of excellent bond behavior between the LMC overlay and the concrete substrate. In this study, the effect of the primary parameters of the concrete substrate (i.e., shrinkage, stiffness and cracking capacity) as well as the LMC overlay thickness on the probability of cracking of the bridge deck slabs using LMC overlays was investigated by carrying out the finite element analysis that simulated the bond behavior of LMC overlays on normal strength concrete (NSC) and HPC bridge deck slabs. Based on the results of the numerical analysis, it is concluded that the relatively high shrinkage strains and stiffness of HPC slabs can increase its probability of cracking in bridge deck slabs using LMC overlay.