• Title, Summary, Keyword: 신뢰성지수

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Reliability-Based Load and Resistance Factor Design (신뢰성 이론에 의한 하중 및 저항계수 설계)

  • Son, Seung Yo;Lee, Jong Heon
    • Journal of The Korean Society of Civil Engineers
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    • v.7 no.4
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    • pp.1-12
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    • 1987
  • The Advanced First Order Second Moment(AFOSM) method is commonly used to determine partial safety factors in the development of probability based LRFD code. However, design format using load and resistance factors based on this method may result in different reliability levels from specified ones. Reliability-Conditioned(RC) method recently proposed by Ayyub et al. gives partial safety factors which do not affect the target reliability level as specified. However, this method has some numerical difficulties and the procedure is not consistent. The proposed RC/AFOSM combined method has not only numerical consistency, but also results in almost constant partial safety factors with respect to various design conditions, and the resulting reliability levels are very close to specified ones.

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Development of Reliability Index for Comparison of Components' Reliability (제품의 신뢰성 수준 비교를 위한 신뢰성 지수 개발)

  • Park, Jung-Won;Ham, Jung-Keol
    • Proceedings of the Korean Reliability Society Conference
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    • pp.140-148
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    • 2006
  • 본 논문에서는 선진 제품의 신뢰성 수준과 국산 제품의 신뢰성 수준 비교 결과를 정량적으로 표시하기 위한 신뢰성지수를 개발하여 제안하였다 본 연구에서 제안한 신뢰성지수는 가장 우수한 제품의 신뢰성수준과 비교하고자 하는 제품의 신뢰성 수준을 점수화한 신뢰성점수의 비로서 나타낸다. 이 때 신뢰성점수는 제품 초기 특성값 산포, 환경시험 후의 특성변화율, 제품 설계 여유도, 제품 수명 또는 고장률의 4가지 항목을 고려하여 미리 정한 점수 산출 기준을 통하여 산출한다. 제안한 신뢰성지수의 적용방법에 대한 이해를 돕기 위하여 구체적인 적용례도 함께 제시하였다.

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Optimum Design of Composite Framed Structures Based Reliability Index (신뢰성지수를 고려한 합성 뼈대구조물의 최적설계에 관한 연구)

  • Jung, Young Chae;Kim, Jong Gil
    • Journal of Korean Society of Steel Construction
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    • v.15 no.4
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    • pp.389-401
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    • 2003
  • The purpose of this study is to develop an algorithm, which can be designed the optimal sections of the composite framed structures constituted with the beams and the columns consisted of H type of steel section and concrete considering the reliability index. The optimized problem or the composite framed structures is formulated with the objective function and the constraints taking the section sizes as the design variables. The objective functions are constituted by the total costs of constructions. Also, the constraints are derived by considering the reliability index of section stress and allowable stress. The algorithm optimized the section of the composite framed structures utilizes the SUMT method using the modified Newton-Raphson direction method. The optimizing algorithm developed in this study is applied to the numerical examples with respecting a one-bay, one-story composite framed structure and a one-bay five-story one for the practical utilization of design on the composite framed structures using the reliability indices$({\beta})$ three and zero. In addition, their numerical results are compared and analyzed to examine the possibility of optimization the applicability, and the convergence this algorithm.

Reliability Analysis Considering Modeling Uncertainty (모델링불확실성을 고려한 신뢰성 해석)

  • Kim, Jeong-Jung
    • Computational Structural Engineering
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    • v.28 no.3
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    • pp.13-17
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    • 2015
  • 본 기사에서는 모델링불확실성(modeling uncertainty)에 따른 신뢰성 해석결과의 가변성(variability)을 가능성 분포함수(possibility distribution function)를 구성하여 해결하는 방법을 AISC(1998), AIJ(1985), CSA(1994)에서 제안된 3개의 최대 D/t 계산식을 예로 들어 소개하였다. 확신정도가 측정된 신뢰성지수 들을 얻을 수 있으며, 확신정도를 고려한 신뢰성지수의 결정이 가능하게 된다. 다양한 형태의 불확실성에 대하여 그 형태에 맞는 적합한 불확실성 모델링을 사용하는 것도 중요하지만, 확률적 표현에 익숙한 우리의 인지구조를 고려하여 기존의 신뢰성 해석에 어떻게 다양한 불확실성 모델링 방법을 접목시킬 것인지에 대한 연구도 중요할 것이다.

Seepage Face and Reliability Indexes of Anisotropic Homogenous Dam at Steady State Condition (비등방 균질 댐의 정상상태에서의 침투면과 신뢰성지수)

  • Mahmood, Khalid;Kim, Jin-Man
    • Journal of the Korean Geotechnical Society
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    • v.28 no.4
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    • pp.35-42
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    • 2012
  • This paper evaluates the effect of anisotropic conductivity on the seepage face and reliability index of an homogeneous dam with and without toe drain. The analysis are conducted under steady state saturated-unsaturated seepage condition using finite element method. Various anisotropic conductivity ratios were interpreted under such conditions as the vertical conductivity is reduced while the horizon conductivity is fixed. The shear strength of soil is defined by the modified Mohr-Coulomb failure criterion. The analysis results demonstrate that the length of seepage face and reliability index at the downstream and upstream of the dam increase with an increasing anisotropic ratio. These results of the seepage face and reliability index, however, depend on the total head difference between the upstream slope and downstream toe. The difference in seepage face and reliability index is attributed to the different equipotential head with different anisotropic ratios of the dam material.

Development of 400kV Oil-filled power cable system with $KPK^{(R)}$ (400kV 반합성지 전력케이블 시스템 개발)

  • Kim, J.S.;Son, S.H.;Youn, B.K.;Lee, I.H.;Cho, H.S.;Jeong, B.L.
    • Proceedings of the KIEE Conference
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    • pp.186-187
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    • 2007
  • 반합성지 절연 전력케이블 시스템은 유전체 손실을 줄이고 절연두께 저감할 수 있으며 경제성면에서도 유리하다는 장점 때문에 많은 사용검토가 이루어져 왔다. 본 논문은 최근 LS전선이 국내 최초로 개발한 400kV급 초고압 반합성지 전력케이블의 반합성지 설계, 케이블 및 접속함 개발, 그리고 인증 Type Test 및 장시간 실증시험등 주요 개발과정을 기술하였다. OF 전력케이블의 오랜 경험과 다양한 연구결과를 바탕으로 반합성지 전력케이블 시스템을 단기 내에 개발하여 전력 케이블 및 접속함에 대하여 국제공인기관인 KEMA로부터 IEC 60141-1에 따른 인증서를 획득하였고, 장시간 실증시험에 성공적으로 완료함으로써 반합성지 절연 전력케이블 시스템 전체의 신뢰성을 확인할 수 있었다.

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An Alternative Perspective to Resolve Modelling Uncertainty in Reliability Analysis for D/t Limitation Models of CFST (CFST의 D/t 제한모델들에 대한 신뢰성해석에서 모델링불확실성을 해결하는 선택적 방법)

  • Han, Taek Hee;Kim, Jung Joong
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.28 no.4
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    • pp.409-415
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    • 2015
  • For the design of Concrete-Filled Steel Tube(CFST) columns, the outside diameter D to the steel tube thickness t ratio(D/t ratio) is limited to prevent the local buckling of steel tubes. Each design code proposes the respective model to compute the maximum D/t ratio using the yield strength of steel $f_y$ or $f_y$ and the elastic modulus of steel E. Considering the uncertainty in $f_y$ and E, the reliability index ${beta}$ for the local buckling of a CFST section can be calculated by formulating the limit state function including the maximum D/t models. The resulted ${beta}$ depends on the maximum D/t model used for the reliability analysis. This variability in reliability analysis is due to ambiguity in choosing computational models and it is called as "modelling uncertainty." This uncertainty can be considered as "non-specificity" of an epistemic uncertainty and modelled by constructing possibility distribution functions. In this study, three different computation models for the maximum D/t ratio are used to conduct reliability analyses for the local buckling of a CFST section and the reliability index ${beta}$ will be computed respectively. The "non-specific ${beta}s$" will be modelled by possibility distribution function and a metric, degree of confirmation, is measured from the possibility distribution function. It is shown that the degree of confirmation increases when ${beta}$ decreases. Conclusively, a new set of reliability indices associated with a degree of confirmation is determined and it is allowed to decide reliability index for the local buckling of a CFST section with an acceptable confirmation level.

Reliability Analysis Models for Maintenance of bridge structures (교량구조물의 유지관리를 위한 신뢰성 해석 모델)

  • Kim, Jong-Gil;Sohn, Yong-Woo;Lee, Cheung-Bin;Ahn, Young-Ki
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.8 no.3
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    • pp.251-261
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    • 2004
  • Recently, the corrosion and aging of bridge structures are of great concern impractical The uncertainties of the corroded reinforced bars in concrete influence not only the safety of the bridge structures, but also the flexural strength of reinforced concrete members. This paper considers these uncertainties by providing a reliability-based framework and show that the identification of the optimum maintenance scenario is a straightforward process. This is achieved by using a computer pro망am for Life Cycle Cost Analysis of Deteriorating Structures (LCCADS). This program can consider the effects of various types of actions on the reliability index profile of a deteriorating structures.

A Study on the Relation of Rebar Corrosion Rate and the Strength Reliability Index of RC Slab Decks having Chloride Contamination (염해 손상을 받는 RC 교량 바닥판의 강도 신뢰성 지수와 철근 부식도 등급과의 관계 연구)

  • Cha, Chul-Jun;Park, Mi-Yun;Cho, Hyo-Nam
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.9 no.2
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    • pp.121-128
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    • 2005
  • This study focuses on evaluating the reliability index of a deck of RC slab having chloride contamination and studying the relation of grades of rebar corrosion and the reliability index of a bridge deck For this purpose, first, the failure probability related to flexural strength was calculated using a model for deterioration, which contains the application of deicing salts that usually causes significant long-term deterioration and reduction in the structural safety for strength of structure. And also, according to the depth of covering, the chloride contents depending on time due to depths of RC slab deck, the appearance time for initial corrosion of rebar and the occurrence time for split of covering were investigated using a MCS method.

A Study on Design Criteria of Rockfall Protection Fence Considering Reliability Index (신뢰성지수를 고려한 낙석방지울타리 설계기준 고찰)

  • Suk, JaeWook;Lee, JongGun;Kim, YongSoo;Moon, JoonShik
    • Tunnel and Underground Space
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    • v.24 no.4
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    • pp.275-281
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    • 2014
  • The performance criteria of rockfall protection fence and reliability index were investigated considering characteristic of rockfall energy occurred at 160 cut slopes in national highway. As a result of study on statistic of variables that decide rockfall energy using Monte-Carlo simulation, the degree of slope was normal distribution type, mass of rockfall and height of slope was lognormal distribution type. The rockfall energy follows lognormal distribution because of statistical characteristic of mass of rockfall. The reliability index of rockfall protection fence was 0.678 and the failure probability of was very high as 24.9%. Proposed performance criteria of rockfall protection fence considering the scale of domestic rockfall energy is maximum 500 kJ and the range of reliability index was from 1.028 to 1.956. the failure probability of rockfall protection fence was from 14.8 to 2.5 percent if applying the performance criteria using the reliability index.