• Title/Summary/Keyword: Ultimate Pressure Capacity

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CONTAINMENT PERFORMANCE EVALUATION OF PRESTRESSED CONCRETE CONTAINMENT VESSELS WITH FIBER REINFORCEMENT

  • CHOUN, YOUNG-SUN;PARK, HYUNG-KUI
    • Nuclear Engineering and Technology
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    • v.47 no.7
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    • pp.884-894
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    • 2015
  • Background: Fibers in concrete resist the growth of cracks and enhance the postcracking behavior of structures. The addition of fibers into a conventional reinforced concrete can improve the structural and functional performance of safety-related concrete structures in nuclear power plants. Methods: The influence of fibers on the ultimate internal pressure capacity of a prestressed concrete containment vessel (PCCV) was investigated through a comparison of the ultimate pressure capacities between conventional and fiber-reinforced PCCVs. Steel and polyamide fibers were used. The tension behaviors of conventional concrete and fiber-reinforced concrete specimens were investigated through uniaxial tension tests and their tension-stiffening models were obtained. Results: For a PCCV reinforced with 1% volume hooked-end steel fiber, the ultimate pressure capacity increased by approximately 12% in comparison with that for a conventional PCCV. For a PCCV reinforced with 1.5% volume polyamide fiber, an increase of approximately 3% was estimated for the ultimate pressure capacity. Conclusion: The ultimate pressure capacity can be greatly improved by introducing steel and polyamide fibers in a conventional reinforced concrete. Steel fibers are more effective at enhancing the containment performance of a PCCV than polyamide fibers. The fiber reinforcementwas shown to bemore effective at a high pressure loading and a lowprestress level.

Evaluation of Ultimate Pressure Capacity of Light Water Reactor Containment Considering Aging of Materials (재료의 경년상태를 고려한 경수로형 격납건물의 극한내압능력 평가)

  • Lee, Sang-Kuen;Song, Young-Chul;Han, Sang-Hoon;Kwon, Yong-Gil
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.5 no.2
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    • pp.147-154
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    • 2001
  • The prestressed concrete containment is one of the most important structures in nuclear power plants, which is required to prevent release of radioactive or hazardous effluents to the environment even in the case of a severe accident. Numerical analyses are carried out by using the ABAQUS finite element program to assess the ultimate pressure capacity of the Y prestressed concrete containment with light water reactor at design criteria condition and aging condition considering varied properties of time-dependant materials respectively. From the results, it is verified that the structural capacity of the Y prestressed concrete containment building under the present, aging condition is still robust. In addition, the parameter studies for the reduction of the ultimate pressure capacity of containment building according to the degradation levels of the main structural materials are carried out. The results show that when the degradations of each materials are considered as individual and combined forms, the influence is large in the order of tendon, rebar and concrete degradation, and tendon-rebar, tendon-concrete and rebar-concrete degradation respectively.

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Study on Pullout Behavior and Determination of Ultimate Uplift Capacity of Pile Driven in Small Pressured Chamber (소형 압력 토조내에 타입된 말뚝의 인발 거동과 극한 인발 지지력 결정에 관한 연구)

  • 최용규
    • Geotechnical Engineering
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    • v.11 no.2
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    • pp.19-28
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    • 1995
  • Based on the various test data acquired in the field, the large pressure chamber and the small pressure chamber, uplift behaviors and method of determining the ultimate uplift capacity of pile driven in small pressure chamber were studied. After uplift pile experienced 2 or 3 sudden slip due to increase of uplift load, complete pullout failure was occurred. Thus, it appears that the ultimate uplift capacity could be identified as the load at displacement where first slip occurs. The ultimate uplift capacity might be determined in every test and the disturbance after first uplift test could be recovered by adding one blow of the drop hammer, which had to depend on the model pile capacity.

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A Study on the Performance Assessment of PHWR Containment Building (가압중수형 원전 격납건물의 성능평가에 관한 연구)

  • Lee, Hong-Pyo;Jang, Jung-Bum
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.24 no.4
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    • pp.449-455
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    • 2011
  • Recently, international collaborative research which was organized at Bhabha Atomic Research Centre in India, was conducted to develop for pressure capacity and nonlinear behavior of PHWR 1/4 scale nuclear containment building between experimental test and numerical code. In this paper, a nonlinear finite element analysis was carried out in order to predict ultimate pressure capacity and nonlinear behavior of the 1/4 scale containment building. The 1/4 scale containment building is consisted of basemat, cylinder wall, dome and 4-buttress. For the finite element analysis, commercial program ABAQUS was used. Finite element models including concrete, rebar and tendon have been developed for assessment of ultimate pressure capacity and failure mode for nuclear containment building. From the analysis results, first crack of the concrete, the yielding of the rebar and ultimate capacity pressure occurred at $1.6P_d$(design pressure), $3.36P_d$ and $4.0P_d$, respectively.

Evaluation of Ultimate Pressure Capacity of Prestressed Concrete Containment Building Considering Aging of Materials (재료의 경년상태를 고려한 PSC격납건물의 극한내압능력 평가)

  • 이상근;송영철;권용길;한상훈
    • Proceedings of the Korea Concrete Institute Conference
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    • 2000.04a
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    • pp.805-810
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    • 2000
  • The purpose of this study is to predict long-term structural safety on the Yonggwang Unit 3 prestressed concrete containment building. The aging-related degradations of its main structural materials are investigated and the effects of the property variation of time-dependent materials on the structural behavior of containment building are also assessed through the analysis on the ultimate pressure capacity. The nonlinear finite element analyses for both the design criteria condition a the present aging condition are conducted to assess the present structural capacity of the containment building As a result, it is verified that the structural capacity of the Yonggwang Unit 3 containment building under the present aging condition is judged to be still rugged. n addition, the sensitivity of the ultimate pressrue capacity of containment building according to th degradation levels of the structural materials are assessed. Finally, it is showed that the sensitivity levels are in the order of the tendon, rebar and concrete in case of individual material degradations, and the tendon-rebar, tendon-concrete and rebar-concrete in case of coupled material degradations.

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A Study on Evaluation of Ultimate Internal Pressure Capacity of CANDU-type Nuclear Containment Buildings (CANDU형 원자로 격납건물의 극한내압능력 평가에 관한 연구)

  • Kim, Sun-Hoon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.24 no.3
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    • pp.343-351
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    • 2011
  • Nuclear containment building is the last barrier for being secure from any nuclear power plant accident. Therefore, it is very important to understand the ultimate capacity of nuclear containment building to loads associated with severe accidents. LOCA (loss of coolant accident) is considered as the basic accidental load and CANDU-type containment building is considered as a target structure in order to conduct the numerical analysis for the structural safety of a containment building. The CANDU-type containment building is a prestressed concrete shell structure which has the dome and the cylindrical wall and is reinforced with bonded tendons. In this paper, the evaluation of ultimate internal pressure capacity was carried out by nonlinear analysis of a prestressed concrete containment building using 3-dimensional structural analysis system.

Evaluation of Ultimate Bearing Capacity on Granular Compaction Pile Considering Various Stresses in a Ground (지중응력의 변화를 고려한 조립토 다짐말뚝의 극한지지력 평가)

  • Kang, Yun;Yun, Ji-Yeon;Chang, Weon-Ho;Kim, Hong-Taek
    • Journal of the Korean Geotechnical Society
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    • v.20 no.2
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    • pp.115-124
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    • 2004
  • Granular compaction pile has the load bearing capacity of the soft ground increase and has the settlement of foundation built on the reinforced soil reduce. The granular compaction group piles also have the consolidation of the soft ground accelerate and prevent the liquefaction caused by earthquake using the granular materials such as sand, gravel, stone etc. However, this method is not widely used in Korea. The granular compaction piles are constructed by grouping them with a raft system. The confining pressure at the center of bulging failure depth is a major variable in estimating the ultimate bearing capacity of the granular compaction piles. Therefore, a share of loading is determined considering the effect of load concentration ratio between the granular compaction piles and surrounding soils, and the variation of the magnitude of the confining pressure. In this study, a method for the determination of the ultimate bearing capacity is proposed to apply a change of the horizontal pressure considering bulging failure depth, surcharge, and loaded area. Also, the ultimate bearing capacity of the granular compaction pile is evaluated on the basis of previous study(Kim et al., 1998) on the estimation of the ultimate bearing capacity and compared with the results obtained from laboratory scale model tests and DEM numerical analysis using the PFC-2D program.

A Model Test Study on the Bearing Capacity of the Crushed Stone Pile (쇄석말뚝의 지지력 특성에 관한 모형시험 연구)

  • 이상익;박용원;김병일;윤길림
    • Proceedings of the Korean Geotechical Society Conference
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    • 2001.03a
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    • pp.299-306
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    • 2001
  • Crushed Stone Pile(CSP) is one of the ground improvement methods available to loose sand and clayey ground by forming compacted CSP in the weak soil layer. The effects of this method are enhancement of ground bearing capacity, reduction of settlement and prevention of lateral ground movement in cohesive layer, reduction of liquefaction potential in sandy ground. This study performs model tests in 1.0m${\times}$1.0m${\times}$1.0m and 1.5m${\times}$1.5m${\times}$l.2m model tank to observe bearing capacity of CSP treated ground. The area replacement ratio of CSP composite ground varies 20%, 30% and 40% with square grid pattern. After the composite ground was consolidated under pressure of 0.5kg/$\textrm{cm}^2$ and 1.0kg/$\textrm{cm}^2$, load tests were carried out. The results show that ultimate bearing capacity increases with area replacement ratio and the preconsolidation pressure of ground.

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Analysis of Bearing Capacity Characteristics on Granular Compaction Pile - focusing on the Model Test Results (조립토 다짐말뚝의 지지력 특성 분석 - 모형토조실험 결과를 중심으로)

  • Kang, Yun;Kim, Hong-Taek
    • Journal of the Korean GEO-environmental Society
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    • v.5 no.2
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    • pp.51-62
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    • 2004
  • Granular compaction piles have the load bearing capacity of the soft ground increase and have the settlement of foundation built on the reinforced soil reduce. The granular compaction group piles also have the consolidation of the soft ground accelerate and have the liquefaction caused by earthquake prevent using the granular materials such as sand, gravel, stone etc. However, this method is one of unuseful methods in Korea. The Granular compaction piles are constructed by grouping it with a raft system. The confining pressure at the center of bulging failure depth is a major variable in relation to estimate for the ultimate bearing capacity of the granular compaction piles. Therefore, a share of loading is determined considering the effect of load concentration ratio between the granular compaction piles and surrounding soils, and varies the magnitude of the confining pressure. In this study, method for the determination of the ultimate bearing capacity is proposed to apply a change of the horizontal pressure considering bulging failure depth, surcharge and loaded area. Also, the ultimate bearing capacity of the granular compaction piles is evaluated on the basis of previous study on the estimation of the ultimate bearing capacity and compared with the results obtained from laboratory scale model tests. And using the result from laboratory model tests, it is studied increase effect of the bearing capacity on the granular compaction piles and variance of coefficient of consolidation for the ground.

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A Study on the Estimation of Ultimate Bearing Capacity of Granular Group Piles (조립토 군말뚝의 극한지지력 평가에 관한 연구)

  • 김홍택;강인규
    • Geotechnical Engineering
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    • v.14 no.5
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    • pp.143-162
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    • 1998
  • In the present study, a procedure to predict the depth from the ground surface to the center of bulging failure zone in each of the square granular group piles under a rigid mat foundation is proposed. This analytical procedure is established on the basis of the conical modeling of bulging failure shape and the replacement ratio of soft foundation soils. considering the effect of a share of procedure to estimate the ultimate cylindrical pressure in the area reinforced with granular piles and the ultimate bearing capacity of each of granular piles in group. This analytical procedure is also established on the basis of the pre-determined depth to the zone of bulging failure and an iterative solution technique. Finally the analytical procedures proposed in this study are verified by analyzing the results of 3D finite element analyses, and the predictions of ultimate bearing capacity of granular piles are compared with the results obtained from the tests, empirical equation and 3D finite element analyses.

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