• Title/Summary/Keyword: 원형철근

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Displacement Ductility of Circular RC Column According to the Spacing of Spirals (나선철근 간격에 따른 원형 RC 기둥의 변위연성도)

  • Ko, Seong Hyun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.2
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    • pp.71-82
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    • 2013
  • Eight small scale circular reinforced concrete columns (4.5 aspect ratio) were tested under cyclic lateral load with constant axial load. The selected test variables are longitudinal steel ratio (2.017%, 3.161%), transverse steel ratio, and axial load ratio (0, 0.07, 0.15). Volumetric ratio of spirals of all the columns is 0.335~0.894% in the plastic hinge region. It corresponds to 39.7~122.3% of the minimum requirement of confining steel by Korean Bridge Design Specifications, which represent existing columns not designed by the current seismic design specifications or designed by seismic concept. The final objectives of this study are to provide quantitative reference data and tendency for performance or damage assessment based on the performance levels such as cracking, yielding, steel fracture, etc. In this paper, describes mainly failure behavior, strength degradation behaviour, displacement ductility of circular reinforced concrete bridge columns with respect to test variables.

Seismic Performance and Flexural Over-strength of Circular RC Column (원형 RC 기둥의 내진성능과 휨 초과강도)

  • Ko, Seong-Hyun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.5
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    • pp.49-58
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    • 2013
  • Eight small scale circular reinforced concrete columns were tested under cyclic lateral load with constant axial load. Test specimens were designed with 4.5 aspect ratio. The selected test variables are longitudinal steel ratio, transverse steel ratio, yielding strength of longitudinal steel and axial load ratio. The test results of columns with different longitudinal steel ratio, transverse steel ratio and axial load ratio showed different seismic performance such as equivalent damping ratio, residual displacement and effective stiffness. It was found that the column with low strength of longitudinal steel showed significantly reduced seismic performance, especially for equivalent damping ratio and residual displacement. The regulation of flexural over-strength is adopted by Korea Bridge Design Specifications (Limited state design, 2012). The test results are compared with nominal strength, result of nonlinear moment-curvature analysis and the design specifications such as AASHTO LRFD and Korea Bridge Design Specifications (Limited state design).

Reliability Analysis of Concrete Filled Carbon Composite Tube (탄소 섬유관으로 구속된 콘크리트 부재의 신뢰성 해석)

  • Kim, Hee-Cheul;Lee, Kyoung-Hun;Hong, Won-Kee;Lee, Young-Hak;Eom, Chul-Hwan
    • Journal of the Earthquake Engineering Society of Korea
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    • v.10 no.5 s.51
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    • pp.1-9
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    • 2006
  • In this study, axial and lateral loading experiments for both circular and square plain concrete columns confined with carbon fiber tube manufactured by carbon filament winding technique were performed. Based on the test results, reliability analyses to estimate strength reduction factors were carried out by utilizing Monte Carlo technique. CASE I was for plain concrete columns confined with the carbon tubes, CASE II was for reinforced concrete columns confined with the carbon tubes. As results, the strength reduction factors, ${\phi}$, were estimated as 0.7 for CASE I and 0.85 for CASE II respectively.

Seismic Performance Evaluation of SRC Column by Quasi-Static Test (준정적 실험에 의한 SRC 합성교각의 내진성능 평가)

  • Han, Jung-Hoon;Park, Chang-Kyu;Shim, Chang-Su;Chung, Young-Soo
    • Journal of the Earthquake Engineering Society of Korea
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    • v.10 no.4 s.50
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    • pp.85-94
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    • 2006
  • In the design of bridge piers in seismic area, the ductility requirement is the most important factor. In order to enhance the seismic performance of RC columns, it is necessary to make the ductility of columns larger by covering RC columns with steel tubes or confining RC columns by arranging transverse reinforcements such as hoop ties closely. Using core steel composite columns is useful as one of the reinforcing RC columns. In this paper, quasi-static tests on concrete encased composite columns with single core steel or multiple steel elements were performed to investigate the seismic performance of the composite columns. Eight concrete-encased composite specimens were fabricated. The cross-sections of these specimens are composed of concrete-encased H-shaped structural steel columns and a concrete-encased circular tube with partial in-filled concrete. Test parameters were the amount of the transverse reinforcements, type and number of encased steel member. Through the tests, it was evaluated the ductility of SRC composite specimens. It has become clear from the test results that encased steel elements makes the deformation capacity of the columns to be larger. The displacement ductility and lateral strength of specimen with concrete-encased circular tube were indicated the biggest value.

Flexure-Shear Behavior of Circular Bridge Columns under Cyclic Lateral Loads (반복 횡하중을 받는 원형교각의 휨-전단 거동)

  • Lee Jae-Hoon;Ko Seong-Hyun;Lee Dae-Hyoung;Chung Young-Soo
    • Journal of the Korea Concrete Institute
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    • v.16 no.6 s.84
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    • pp.823-832
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    • 2004
  • The purpose of this research is to investigate the flexure-shear behavior of bridge columns under seismic loads. Four full scale circular reinforced concrete columns were tested under cyclic lateral load with constant axial load. The selected test variables are aspect ratio(1.825, 2.5, 4.0), transverse steel configuration, and longitudinal steel ratio. Volumetric ratio of transverse hoop of all the columns is 0.0023 in the plastic hinge region. It corresponds to $24\%$ of the minimum requirement of confining steel by Korean Bridge Design Specifications, which represent existing columns not designed by the current seismic design specifications or designed by limited ductility concept. The columns showed flexural failure or flexure-shear failure depending on the test variables. Failure behavior and seismic performance are investigated and discussed in this paper.

A stress-strain Model of High-strength concrete confined with Transverse Reinforcement (횡보강철근으로 구속된 고강도 콘크리트의 응력-변형률 구속 모델)

  • Moon, Cho-Hwa;Park, Jong-Wook;Kim, Sang-Woo;Kim, Kil-Hee;Lee, Jung-Yoon
    • Proceedings of the Korea Concrete Institute Conference
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    • 2010.05a
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    • pp.87-88
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    • 2010
  • The strength and ductile capacity of reinforced concrete column can be improved by confinement using transverse reinforcement. Variety stress-strain models about the reinforced concrete confined by transverse reinforcement has been proposed. In this paper, parameters which effect to the ultimate confinement stress of circular cylinder confined by high strength transverse steel is examined. And the possion's ratio equation is proposed by analysis of strain between concrete and transverse reinforcement.

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Load transfer test of circular anchorage system according to ETAG 013 (ETAG 013 규정에 따른 원형 정착구의 하중전달실험)

  • Kim, Bum-Joon;Kim, Hyun-Gi
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.5
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    • pp.167-175
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    • 2018
  • Load transfer experiments have been carried out to evaluate the performance of the anchorage and it has been stated that the specimens were manufactured and tested according to ETAG 013. On the other hand, the amount of spiral reinforcement and auxiliary reinforcement exceeded the amount specified in ETAG 013. In this study, the load transfer test method and the criteria specified in ETAG 013 were considered and the PT anchorage system was applied to manufacture specimens with high strength concrete and a high tensile prestressing strand. A load transfer test according to ETAG 013 was performed to evaluate the performance of the circular anchorage. As a result, it was confirmed that ETAG 013 is a very strict specification that does not satisfy the performance of an anchorage unless the specimens of an appropriate size and spiral reinforcement are used. To assess the stability of the specimens, increasing the size of the specimen by 15%, rather than increasing the amount of auxiliary reinforcement, is considered to be the correct method in accordance with ETAG 013.

Seismic Retrofit of GFRP Wrapping on the Lap-spliced Bridge Piers (GFRP 래핑에 의한 겹침이음된 교각의 내진보강)

  • Youm, Kwang Soo;Kwon, Tae Gyu;Lee, Young Ho;Hwang, Yoon Kook
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.2A
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    • pp.311-318
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    • 2006
  • This paper presents experimental studies on investigating the seismic retrofit performance of reinforced concrete circular columns with poor lap-splice details using GFRP wrapping. Five full-scale model columns have been tested. The prototype structure is an existing circular reinforced concrete bridge piers designed following the pre-seismic codes and constructed in South Korea in 1979. The as-built column will be expected to suffer brittle failure due to the bond failure of lap-spliced longitudinal reinforcement. The retrofitted columns using GFRP wrapping showed significant improvement of seismic performance. However, the predicted flexural failure mode was not achieved and the longitudinal bars were not yielded. Failure modes of the retrofitted columns are considered to be the gradually delayed bond slip in lap-spliced longitudinal reinforcement. Suggested retrofit design methods using GFRP were validated experimentally.

Seismic Performance and Flexural Over-strength of Hollow Circular RC Column with Longitudinal Steel Ratio 2.017% (축방향철근비 2.017%인 중공 원형 RC 기둥의 내진성능과 휨 초과강도)

  • Ko, Seong-Hyun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.1
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    • pp.1-8
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    • 2017
  • Three small scale hollow circular reinforced concrete columns with aspect ratio 4.5 were tested under cyclic lateral load with constant axial load. Diameter of section is 400 mm, hollow diameter is 200 mm. The selected test variable is transverse steel ratio. Volumetric ratios of spirals of all the columns are 0.302~0.604% in the plastic hinge region. It corresponds to 45.9~91.8% of the minimum requirement of confining steel by Korean Bridge Design Specifications, which represent existing columns not designed by the current seismic design specifications or designed by seismic concept. The longitudinal steel ratio is 2.017%. The axial load ratio is 7%. This paper describes mainly crack behavior, load-displacement hysteresis loop, seismic performance such as equivalent damping ratio, residual displacement and effective stiffness and flexural over-strength of circular reinforced concrete bridge columns with respect to test variable. The regulation of flexural over-strength is adopted by Korea Bridge Design Specifications (Limited state design, 2012). The test results are compared with nominal strength, result of nonlinear moment-curvature analysis and the design specifications such as AASHTO LRFD and Korea Bridge Design Specifications(Limited state design).

A Seismatic Performance Analysis of Circular RC Bridge Piers I. Evaluation of Influence Parameters of Confinement Steel Ratio (원형 철근콘크리트 교각의 내진성능 I. 심부구속철근비 영향 변수 평가)

  • Lee Dae-Hyoung;Park Chang-Kyu;Kim Hyun-Jun;Chung Young-Soo
    • Journal of the Korea Concrete Institute
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    • v.17 no.4 s.88
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    • pp.603-611
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    • 2005
  • For the establishment of rational seismic design code for RC (reinforced concrete) bridge pier, this paper has analyzed the seismic code of RC bridge pier specified in )veil-known codes such as KHBDS (Korea Highway Bridge Design Specification), AASHTO Standard, ATC-32, Eurocode 8, NZS 3101, etc. So as to secure aseismic ductility of RC pier, transverse confinement steel ratios of those codes have been examined together with other design parameters such as strength of concrete and reinforcing steel, axial force ratio, aspect ratio, longitudinal steel ratio, etc. However, there has been arisen a doubt for the validity of those parameters. Thus, the objective of this study is to quantitatively evaluate the validity of design parameter of each code on the experimental seismic ductility for about 80 test specimens. It was concluded from this study that the axial force ratio is a dominant factor for the seismic displacement ductility. Therefore, it Is desirable that the axial force ratio be further taken into account in the corresponding seismic design formula of RC bridge pier in current KHBDS.