• Title, Summary, Keyword: confinement

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Status Analysis for the Confinement Monitoring Technology of PWR Spent Nuclear Fuel Dry Storage System (경수로 사용후핵연료 건식저장시스템의 격납감시 기술현황 분석)

  • Baeg, Chang-Yeal;Cho, Chun-Hyung
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.14 no.1
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    • pp.35-44
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    • 2016
  • Leading national R&D project to design a PWR spent nuclear fuel interim dry storage system that has been under development since mid-2009, which consists of a dual purpose metal cask and concrete storage cask. To ensure the safe operation of dry storage systems in foreign countries, major confinement monitoring techniques currently consist of pressure and temperature measurement. In the case of a dual purpose metal cask, a pressure sensor is installed in the interspace of bolted double lid(primary and secondary lid) in order to measure pressure. A concrete storage cask is a canister based system made of double/redundant welded lid to ensure confinement integrity. For this reason, confinement monitoring method is real time temperature measurement by thermocouple placed in the air flow(air intake and exit) of the concrete structure(over pack and module). The use of various monitoring technologies and operating experiences for the interim dry storage system over the last decades in foreign countries were analyzed. On the basis of the analysis above, development of the confinement monitoring technology that can be used optimally in our system will be available in the near future.

Confinement evaluation of concrete-filled box-shaped steel columns

  • Susantha, K.A.S.;Ge, Hanbin;Usami, Tsutomu
    • Steel and Composite Structures
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    • v.1 no.3
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    • pp.313-328
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    • 2001
  • This paper presents a three-dimensional finite element analysis methodology for a quantitative evaluation of confinement in concrete-filled box-shaped unstiffened steel columns. The confinement effects of concrete in non-circular sections can be assessed in terms of maximum average lateral pressure. A brief review of a previous method adopted for the same purpose is also presented. The previous method is based on a two-dimensional finite element analysis method involving a concrete-steel interaction model. In both the present and previous methods, average lateral pressure on concrete is computed by means of the interaction forces present at the concrete-steel interface. Subsequently, the strength enhancement of confined concrete is empirically related to the maximum average lateral pressure. The results of the former and latter methods are then compared. It is found that the results of both methods are compatible in terms of confined concrete strengths, although the interaction model yields a somewhat overestimated estimation of confinement than those of the present method when relatively high strength concrete is used. Furthermore, the confinement in rectangular-shaped sections is investigated and the reliability of previously adopted simplifications in such cases is discussed.

Design of Boundary Confinement of Structural Walls (구조벽의 단부 횡보강 설계)

  • Kang, Su-Min;Park, Hong-Gun
    • Journal of the Korea Concrete Institute
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    • v.15 no.6
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    • pp.877-887
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    • 2003
  • For a performance-based design of structural walls, it is necessary to develop a rational design method for determining the length and detail of boundary confinement so as to satisfy the given ductility demand. In the present study, the curvature capacity of a structural wall with boundary confinement was estimated considering the effects of various design parameters. The curvature demand of the plastic hinge corresponding to the given design displacement was also determined. By equalizing the curvature capacity to the demand, a design method for determining the length of boundary confinement, was developed. According to the design method, the length of boundary confinement increases as axial compressive load and design displacement increase, and as concrete strength, wall thickness, amount of lateral reinforcement and aspect ratio decrease. A study was performed on details for effective lateral confinement of walls with rectangular cross-section. Based on the findings, design guidelines on spacings of ties and cross-ties were proposed.

Ductility Confinement of RC Rectangular Shear Wall (장방형 철근 콘크리트 전단벽의 연성 보강)

  • 강수민;박홍근
    • Journal of the Korea Concrete Institute
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    • v.14 no.4
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    • pp.530-539
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    • 2002
  • In designing the boundary confinement of shear walls, the current design provisions and recommendations are empirical and prescriptive; they specify a certain confinement length and details, regardless of the actual requirement of ductility Therefore, they are inappropriate to the performance based-design. The purpose of the present study is to develop a ductility design method that Is applicable to the performance based-design of shear wall. For the purpose, experimental studies were performed to investigate variations in the ductility of shear walls with the length of the boundary confinement. Five specimens modeling the compressive zone of cross sections with different confinement area were tested against eccentric vertical load. Through the experimental studies, strength, ductility, and failure mode of the compression zone were investigated. In addition, nonlinear numerical analyses for the overall cross-sections of shear wall were performed to investigate variations of the stress and strain profiles with the length of compression zone. On the basis of the experimental and numerical studies, a ductility design method for shear wall was developed. By using the proposed design method, for a given ductility demand, the area of lateral confinement and corresponding reinforcement ratio can be precisely determined so that the ductile behavior and economical design are assured.

Axial capacity of reactive powder concrete filled steel tube columns with two load conditions

  • Wang, Qiuwei;Shi, Qingxuan;Xu, Zhaodong;He, Hanxin
    • Steel and Composite Structures
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    • v.31 no.1
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    • pp.13-25
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    • 2019
  • Reactive powder concrete (RPC) is a type of ultra-high strength concrete that has a relatively high brittleness. However, its ductility can be improved by confinement, and the use of RPC in composite RPC filled steel tube columns has become an important subject of research in recent years. This paper aims to present an experimental study of axial capacity calculation of RPC filled circular steel tube columns. Twenty short columns under axial compression were tested and information on their failure patterns, deformation performance, confinement mechanism and load capacity were presented. The effects of load conditions, diameter-thickness ratio and compressive strength of RPC on the axial behavior were further discussed. The experimental results show that: (1) specimens display drum-shaped failure or shear failure respectively with different confinement coefficients, and the load capacity of most specimens increases after the peak load; (2) the steel tube only provides lateral confinement in the elastic-plastic stage for fully loaded specimens, while the confinement effect from steel tube initials at the set of loading for partially loaded specimens; (3) confinement increases the load capacity of specimens by 3% to 38%, and this increase is more pronounced as the confinement coefficient becomes larger; (4) the residual capacity-to-ultimate capacity ratio is larger than 0.75 for test specimens, thus identifying the composite columns have good ductility. The working mechanism and force model of the composite columns were analyzed, and based on the twin-shear unified strength theory, calculation methods of axial capacity for columns with two load conditions were established.

Confinement of Columns using Headed Bars (Headed Bars를 활용한 기둥의 구속효과에 대한 연구)

  • 김영훈;윤영수;데니스미첼
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.929-934
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    • 2002
  • Eight full-scale columns were constructed and tested under monotonic axial compression loading to investigate the influence of headed bars on the confinement of the concrete. One column represented a column with no transverse reinforcement and another column had poor detailing and little confinement. A third column contained seismic hoops and crossties, which represented current detailing practice for significant confinement. A fourth column test is conducted to investigate the response with the seismic crossties replaced by headed bars. Two column specimens were constructed and tested with all of the transverse reinforcement provided by headed bars. These six specimens enabled an assesment of the effectiveness of headed bars in confining the concrete. It was found that the use of headed bars improved the confinement of the columns. Two additional specimens were constructed without any transverse reinforcement. These columns were later retrofitted, by drilling horizontal holes in the columns, adding special headed bars (one head fixed and the other head threaded) and then filling the drilled holes with epoxy. These retrofitted specimens with these added headed bars provided insight into the rehabilitation of older structures containing poorly detailed columns. All of the test specimens were instrumented to determine strain localization during failure and to monitor the strain in the longitudinal and transverse reinforcement.

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Assessment of Ductility for the RC Piers with Transverse Reinforcement and Application of Carbon-Fiber Red (횡방향 구속철근의 배근방법에 따른 철근콘크리트 교각의 연성 평가 및 탄소섬유 ROD의 적용)

  • 이영호;이학은
    • Journal of the Korea Concrete Institute
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    • v.14 no.1
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    • pp.8-15
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    • 2002
  • This paper presents a study carried out for the seismic capacity in reinforced concrete(RC) piers by the confinement effect of transverse reinforcement as such a hooked-tied, welded-tied and spiral reinforcement. In order to assess the seismic capacity with transverse reinforcement, experiment리 and analytical methods were adopted. A RC column survey was conducted based on eight one-fourth scale single circular column specimens designed and tested under slow horizontal cyclic loads. Two cases were analyzed. The confinement effect of concrete by transverse reinforcement is considered not in Case 1 but in Case 2. Also, we studied the propriety of making use of the method in which a carbon fiber rod replace spiral reinforcement in RC piers. In experimental tests, a welded-tied and spiral reinforcement has a good seismic capacity, but a carbon fiber rod presents low ductility in comparison with a hooked-tied reinforcement. In an analytical study, displacement ductility is approximate to the experimental result because of considering the confinement effect of the transverse reinforcement. Even if the confinement effect of the transverse reinforcement is considered, the analytical results for ductility of the specimens with welded-tied and spiral reinforcement show an excessive underestimation of the experimental results.

Seismic Performance of RC Columns Confined by Outside Lateral Reinforcement (외측 횡보강재로 구속된 철근콘크리트 기둥의 내진성능)

  • Lee, Do Hyung;Oh, Jangkyun;Yu, Wan Dong;Choi, Eunsoo
    • Journal of The Korean Society of Civil Engineers
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    • v.32 no.3A
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    • pp.189-196
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    • 2012
  • In this paper, reinforced concrete columns test has been conducted under repeated lateral load reversals. The test columns have been reinforced with outside lateral confinement members in addition to transverse reinforcements. For this purpose, a strainless steel and a GFRP have been employed for the lateral confinement members. Primary parameters are types, thickness and spacing of the lateral confinement members. Experimental results reveal that columns reinforced with lateral confinement members exhibit improved ductility and energy dissipation capacity in comparison with those unreinforced. It is thus concluded that the present approach can be of a useful scheme for the seismic retrofitting of reinforced concrete columns.

Confinement Effects of Concrete by GFRP Shells (GFRP Laminates에 의한 콘크리트의 구속)

  • 조순호;선성규;정창원;조규성
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.937-942
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    • 2003
  • Three series of 36 short circular columns confined by wraps, full shells and partial shells were tested by varying the thickness of GFRP laminates. An assessment of the effectiveness of the existing models on confinement of concrete columns with FRP was made for present tests. Test results indicated significant increases in strength and deformability compared with those in unconfined concrete, particularly warp and full shell confinement. Existing predictive equations for peak strength and strain of confined concrete showed a large scatter and varied considerably, resulting from the realistic fracture strains of FRP nor considered.

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An Analytical Study on Confinement Effect of Transverse Reinforcement and Cross-Tie in Hollow Rectangular Sectional Columns (중공사각단면 기둥에 있어서 횡철근과 Cross-tie의 횡방향 구속 효과에 대한 해석적 연구)

  • 김익현;정영식;신원철;선창호
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.617-620
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    • 2003
  • This paper presents the confinement effect of transverse reinforcement and cross-tie in hollow rectangular sectional columns. 20 analytical models with different amounts of transverse reinforcement and cross-tie in a plastic hinge region were analyzed by 3D nonlinear FEM. The analytical results show that the higher ductility can be achieved by the resonable combination of transverse re-bar and cross-tie providing sufficient lateral confinement.

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