• Title, Summary, Keyword: 한계하중

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Engineering Estimation of Limit Load Solution for Wall-Thinned Pipes Considering Material Properties (재료물성을 고려한 감육배관의 공학적 한계하중해 제시)

  • Choi, Jae-Boong;Kim, Jin-Su;Goo, Bon-Geol;Kim, Young-Jin;Choi, Young-Hwan
    • Proceedings of the KSME Conference
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    • pp.351-356
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    • 2001
  • A potential loss of structural integrity due to aging of nuclear piping may have a significant effect on the safety of nuclear power plants. In particular, failures due to the erosion and corrosion defects are a major concern. As a result, there is a need to assess the remaining strength of pipe with erosion/corrosion defects. In this paper, a limit load solution for the eroded and corroded SA106 Grade B pipes subjected by internal pressure is developed. based in 3-D finite element analyses, considering a wide range of the shape of pipeline, flaw depth and axial flaw length parametrically.

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Effect of Internal Pressure on Plastic Limit Loads for Elbows with Circumferential Through-wall Crack under Closing Bending Incorporating Large Geometry Change Effects (대변형 효과를 고려한 원주방향 관통균열 엘보우의 닫힘굽힘 한계하중에 미치는 내압 영향 평가)

  • Hong, Seok-Pyo;Kim, Yun-Jae
    • Proceedings of the KSME Conference
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    • pp.1778-1782
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    • 2007
  • Based on three-dimensional (3-D) FE limit analyses, this paper estimates effect of internal pressure on plastic limit loads for elbows with circumferential through-wall crack under in-plane bending incorporating large geometry change effects. Circumferential through-wall crack in extrados is considered. The FE limit analyses using the large geometry change option provide plastic collapse loads (using the twice-elastic-slope method). For the bending mode, closing bending is considered. Other relevant variables affecting plastic limit loads are systematically varied, related to pipe bend geometry (the mean radius, thickness and bend curvature) and defect geometry (the length of circumferential through-wall crack).

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Limit Load Solutions for Piping Branch Junctions with local wall-thinning under Internal Pressure (감육이 존재하고 내압을 받는 T 분기관의 한계하중 평가식)

  • Ryu, Kang-Mook;Kim, Yun-Jae;Lee, Kuk-Hee;Park, Chi-Yong;Lee, Sung-Ho;Kim, Tae-Ryong
    • Proceedings of the KSME Conference
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    • pp.1813-1817
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    • 2007
  • The present work presents plastic limit load solutions for piping branch junctions with local wall-thinning, based on detailed three-dimensional (3-D) and small strain FE limit analyses using elastic-perfectly plastic materials. Three types of loading are considered; internal pressure, in-plane bending on the branch pipe and in-plane bending on the run pipe. The wall-tinning located on variable area of the piping branch junction is considered. A wide range of piping branch junction and wall-thinning geometries are considered. Comparison of the proposed solutions with FE results shows good agreement

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Limit load analyses of weld-center cracked plates under tension (용접부 중앙에 균열이 존재하는 인장 평판에 대한 한계하중 해석)

  • Song, Tae-Kwang;Kim, Yun-Jae;Kim, Jong-Sung;Jin, Tae-Eun
    • Proceedings of the KSME Conference
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    • pp.1830-1835
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    • 2007
  • In the present work, the effect of strength mismatch on plastic limit loads is quantified for strength-mismatched plates with constant-depth surface cracks under tension, via three-dimensional, small strain elastic-perfectly plastic finite element analyses. Relevant variables related to plate and crack geometries are systematically varied, in addition to the weld width. An important finding is that a parameter related to the weld width-to-ligament ratio is proposed, based on which limit loads can be uniquely quantified. The proposed limit load solutions is a valuable input to estimate nonlinear fracture mechanics parameters based on the reference stress approach.

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고리 1호기 원자로냉각제 배관의 파단전누설 개념 평가

  • 우호길;송동수
    • Proceedings of the Korean Nuclear Society Conference
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    • pp.344-349
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    • 1998
  • 고리 1호기 원전의 원자로냉각재 배관의 파단전누설개념 적용성을 평가하기 위하여 일반적인 파단전누설 절차 및 기준을 검토하였다. 파단전누설 타당성을 검토하기 위하여는 한계하중방법 및 J-T 방법을 비교검토 하였다. 그리고 원자로냉각재 배관에 대해서는 탄소강일 경우와 스테인레스강에 대하여 분석하였고, 가압기 밀림관에 대해서는 열응력을 계산하였다. 그리고 원자로 냉각재 배관에 가상의 관통균열의 파괴안전성은 유한요소법을 이용한 탄소성파괴역학을 통하여 분석하였다. 분석결과 한계하중법과 J-T 방법 모두 스테인레스강과 탄소강재질에 대해 적용 가능한 것으로 나타났다.

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Effects of Failure Mode II on Crack Initiation and Crack propagation Steps Using Multilevel Fatigue Loading Test (다단계 피로하중 실험을 통한 균열 발생 및 전파단계에서 파괴모드 II 영향 분석)

  • Hong, Seok Pyo;Park, Sae Min;Kim, Ju Hee
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.41 no.9
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    • pp.853-860
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    • 2017
  • To evaluate the effects of mode II on the crack initiation and propagation stages, the effects in the fatigue threshold region under a mixed-mode I+II loading state was experimentally investigated. In the case of mixed-mode I + II, during the crack initiation stage, as the loading application angle (${\theta}$) increased, cracks occurred in the lower load owing to the effects of mode II, while the crack propagation rate decreased. The effects of mode II were experimentally investigated in the crack propagation stage by means of multilevel loading direction variation. Following mixed-mode I+II ($0^{\circ}{\rightarrow}{\theta}{\rightarrow}60^{\circ}$), as the load application angle increased, the fatigue crack propagation rate decreased, as did the fatigue crack propagation rate, which occurred later. Following mixed-mode I + II in case of(${\theta}{\geq}75^{\circ}$), the fatigue crack propagation rate was found to increase, while the fatigue life decreased.

Analysis of Design Live Load of Railway Bridge Through Statistical Analysis of WIM Data for High-speed Rail (고속철도 WIM 데이터에 대한 통계분석을 통한 철도교량 설계활하중 분석)

  • Park, Sumin;Yeo, Inho;Paik, Inyeol
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.28 no.6
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    • pp.589-597
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    • 2015
  • In this paper, the live load model for the design of high-speed railway bridge is analyzed by statistic and probabilistic methods and the safety level that is given by the load factors of the load combination is analyzed. This study is a part of the development of the limit state design method for the railway bridge, and the train data collected from the Gyeongbu high-speed railway for about one month are utilized. The four different statistical methods are applied to estimate the design load to match the bridge design life and the results are compared. In order to examine the safety level that the design load combination of the railway bridge gives, the reliability indexes are determined and the results are analyzed. The load effect from the current design live load for the high-speed rail bridge which is 0.75 times of the standard train load is came out greater than at least 30-22% that from the estimated load from the measured data. If it is judged based on the ultimate limit state, there is a possibility of additional reduction of the safety factors through the reliability analysis.

The Suggestion of Seismic Performance Values on Connections for Performance Based Design of Steel Structures (강구조 성능기반설계를 위한 접합부의 내진성능평가치 제안)

  • Oh, Sang-Hoon;Oh, Young-Suk;Hong, Soon-Jo;Lee, Jin-Woo
    • Journal of Korean Society of Steel Construction
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    • v.23 no.2
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    • pp.147-158
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    • 2011
  • The purpose of this research was to analyze the connections of the seismic-performance values for domestic-performance-based designs. Basic research on the performance design method has been increasing of late, along with performance-based organization investigations. These investigations concern the performance level state of steel structure buildings. According to the performance limit state, seismic-performance values should be presented as appropriate steel structure engineering amounts. The first step, based on the full-scale steel structure experiments, involves researching on the making of a basic document. The moment-rotation angle relationship results of the experiment on the moment-frame connection were used to assort the functional and undamaged limits, which were assumed to be less than the yield moment. Moreover, the repairable and safety limits, which were assumed to exist between the yield and maximum moments, were assorted by investigating the accumulated plastic deformation ratio.

Vertical Direction Redistribution of Beam Moments in the Seismic Design of RC Frame (RC 골조의 내진설계에서 보 모멘트의 수직방향 재분배)

  • Kim, Dae-Kon
    • Journal of the Korean Association for Spatial Structures
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    • v.11 no.1
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    • pp.57-66
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    • 2011
  • For the lateral load resistance of a RC frame in a medium risk seismic zone, the strength of lower story beams and columns should be larger than those of the upper stories. However, the lateral loads can be accommodated by redistributing design beam moments vertically as well as horizontally so all beams end up with identical strengths. This paper looks at the impact of the vertical redistribution of beam moments to provide identical beam strength over as many floors as possible. Two-bay six-story RC frame was designed with and without vertical beam moment redistribution and its seismic performance were evaluated by using push-over limit analysis and by non-linear time history dynamic analysis. Analytical results show that with the use of vertical beam moment redistribution the increase in the ductility demand is similar to the proportion of moment redistribution applied, but this additional demand is below the ductility capacity of well detailed RC members.

Seismic Design and Analysis of Seismically Isolated KALIMER Reactor Structures (면진된 KALIMER 원자로 구조물의 내진설계 및 지진해석)

  • 이형연
    • Journal of the Earthquake Engineering Society of Korea
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    • v.3 no.1
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    • pp.75-92
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    • 1999
  • In this paper, the seismic analysis model for seismically isolated KALIMER reactor structures is developed and the modal analysis and the seismic time history analysis are carried out for seismic isolation and non-isolation cases. To check the seismic stress limit according to the ASME Code, the equivalent seismic stress analyses are preformed using the 3-D finite element model. From the seismic stress analysis, the seismic margins are calculated for structural members. The limit of seismic load is defined to show that the maximum input acceleration ensures the structural safety for seismic load. In comparison of seismic responses between seismic isolation and non-isolation cases, the seismic isolation design gives significantly reduced acceleration responses and relative displacements between structures. The seismic margin of KALIMER reactor structure is high enough to produce the limit seismic load 0.8g.

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