• Title/Summary/Keyword: 나선형 철근

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Confinement Effect of High-Strength Steel Spirals According to Compressive Strength of Concrete (콘크리트 압축강도에 따른 고강도 나선철근의 횡구속 효과)

  • Kim, Sang Woo;Kim, Young Seek;Yun, Gun Jin;Lee, Jung Yoon;Kim, Kil Hee
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.16 no.4
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    • pp.89-98
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    • 2012
  • This study estimates the performance of steel spirals according to the compressive strength of the concrete. A total of 24 confined concrete cylinders ($150{\times}300mm$) were cast and tested under monotonic concentric compression. The main test parameters were the yield strength of spiral reinforcements and the compressive strength of the concrete. To effectively evaluate the confinement effect according to the yield strength of steel spirals, the external diameter of steel spirals was designed to be same as the diameter of specimen. The experimental results indicated that the performance of confinement of steel spirals increased as the yield strength of spiral reinforcement increased and the compressive strength of the concrete decreased. Furthermore, existing analytical models were used for predicting the stress versus axial strain relationships of specimens tested in this study. It can be concluded that the accuracy of the analytical models deteriorated as the yield strength of steel spirals and the compressive strength of the concrete increased.

Behavior of Circular Concrete Cylinders Confined with Both Steel Spirals and Fiber Composites (나선형 철근 및 섬유에 의하여 동시에 구속된 원형 콘크리트 실린더의 거동)

  • Lee Jung-Yoon;Oh Young-Jun;Jeong Hoon-Sik
    • Journal of the Korea Concrete Institute
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    • v.16 no.2 s.80
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    • pp.175-184
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    • 2004
  • When the columns of existing RC structures are repaired with FRP composites, the core concrete of the columns is confined by both materials of steel spirals (or steel hoops) and FRP composites because the FRP composites wrap the existing columns which have been already confined with steel spirals or hoops. As the stress-strain curves of steel and fiber are different to each other, the behavior of concrete columns confined with both steel spiral and FRP composites is also different to that of concrete columns confined with only steel spiral or FRP composites. Twenty four RC cylinders were tested in order to observe the behavior of RC cylinders confined with both materials. The observed results of the test showed that the behavior of the test cylinders confined with both materials was quite different to that of cylinders confined with only one material.

Punching Shear Strength of Slab-Column Interior Connection Considering Anchorage Performance of Shear Reinforcements (전단보강재의 정착성능을 고려한 슬래브-기둥 내부접합부의 뚫림전단강도)

  • Jung, Hyung-Suk;Choi, Hyun-Ki;Chung, Joo-Hong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.26 no.2
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    • pp.51-58
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    • 2022
  • Flat plate slab is cost-efficient structural system widely used in high rise building, apartment and parking garages. But flat plate-column connections are so weak against punching shear failure that it may cause collapse of overall structure. In this study, spiral type shear reinforcement which increases the shear strength and ductility of the plate-column connection and has good workability was proposed. And experimental test was performed to verify the punching shear capacity of spiral type shear reinforcement. The current code does not accurately estimate the punching shear strength of slab-column connection with shear reinforcement because slab is so slender that punching failure may occurred before shear reinforcement reached yield stress. Therefore modified equation of ACI code for punching shear strength was proposed base on finite element analysis using LUSAS program, and data analysis from CEB-FIP database.

A Study On Structural Behavior of Anchor Pile Precast Retaining Wall with Screw Shape Flange (나선형 플렌지가 설치된 앵커파일 프리캐스트 옹벽의 구조적 거동에 관한 연구)

  • Choi, Seung-Seon;Ahn, Tae-Bong;Kim, Woo-Ki
    • Journal of the Korean Geotechnical Society
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    • v.29 no.11
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    • pp.129-138
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    • 2013
  • In this study, Anchor Pile Precast Retaining Wall (APC) with screw shape flange was investigated and the results were arranged for designing APC specifications. Since precast materials require special care when they are manufactured, carried or treated, more accurate design and analysis of optimized dimension are needed : thus moment distribution of front foot was checked. Through full-scale field test, form and optimal stiffening shape were obtained and through fracture test with real load, applicable load was reasonably calculated. Research result in this thesis could be used as guideline or standard of designing and constructing Anchor Pile Precast Retaining Wall with screw shape flange.

A Study on the Application of GFRP Rock Bolt Sensor through Field Experiment and Numerical Analysis (현장실험과 수치해석을 통한 GFRP 록볼트 센서의 적용성 연구)

  • Lee, Seungjoo;Chang, Suk-Hyun;Lee, Kang-Il;Kim, Bumjoo;Heo, Joon;Kim, Yong-Seong
    • Journal of the Korean Geosynthetics Society
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    • v.18 no.4
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    • pp.129-138
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    • 2019
  • In this study, the rebar rock bolt sensor and GFRP rock bolt sensor, which can be monitored, were embedded in a large model slope, and the behavior of slopes occurred in the early stage of slope collapse was analyzed after performing the field failure test, numerical analysis of the individual element method and finite element method. By comparing and analyzing the field test and numerical analysis results, field applicability of rock slope collapse monitoring on the rebar rock bolt sensor and GFRP rock bolt sensor was investigated. Through this study, smart slope collapse prediction and warning system was developed, which can be used to induce effective evacuation of residents living in the collapsible area by detecting landslide and ground decay precursor information in advance.

Experimental Study on Behavior of Confined Concrete with Electric Arc Furnace Oxidizing Slag Aggregates (전기로 산화 슬래그 골재를 사용한 콘크리트의 횡 구속 거동에 관한 실험적 연구)

  • Kim, Sang-Woo;Lee, Jung-Mi;Lee, Yong-Jun;Jung, You-Jin;Kim, Kil-Hee
    • Journal of the Korea Concrete Institute
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    • v.23 no.2
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    • pp.195-201
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    • 2011
  • This paper estimates the structural performance of spirally confined concrete having electric arc furnace (EAF) oxidizing slag aggregates. The EAF oxidizing slag is a by-product generated from iron and steel industry. The EAF oxidizing slag have been largely put to low-value-added uses due to its expansive properties of the free-CaO and free-MgO. Recently, this problem has been solved by the advances in steelmaking technology and thereby stabilizing EAF oxidizing slag aggregate. To verify the application of the EAF oxidizing slag aggregate to the structural concrete usage, a total of 27 cylindrical specimens with a diameter of 150 mm and a height of 300 mm were cast and tested. The test parameters were aggregate type and spiral reinforcement yield strength. Experimental results showed that the structural performance of specimens with EAF oxidizing slag aggregates was equivalent to that of confined concrete with natural aggregates.

Behavior According to Confinement of Compressive Concrete on Flexural Members Reinforced with FRP Bars (FRP bar를 주근으로 사용한 콘크리트 휨부재의 압축측 콘크리트 구속에 따른 거동)

  • Seo, Dae-Won;Han, Byum-Seok;Shin, Sung-Woo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.12 no.3
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    • pp.110-118
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    • 2008
  • The use of FRP bar as reinforced concrete beams is considered as one of the most prominent solution that may overcome the corrosion of reinforcing steel bars. However, in the case of FRP reinforced concrete, both the reinforcing and the reinforced materials are brittle. For this reason, ductility of structures with FRP reinforcement is much less than that of structures with steel reinforcements. In this study, a method has been suggested to provide a meaningful quantification of ductility for concrete beams reinforced with FRP bars. This paper shows which the confinement to the compression concrete by the spiral can increase the ductility of FRP over-reinforced concrete beams.

Load Transfer Test of Spirally Reinforced Anchorage Zone for Banded Tendon Group (나선형 원형철근으로 보강된 집중배치 텐던 정착구역에 대한 하중전달시험)

  • Cho, Ah Sir;Kang, Thomas H.K.
    • Journal of Korean Association for Spatial Structures
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    • v.17 no.1
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    • pp.59-67
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    • 2017
  • In this study, load transfer tests based on KCI-PS101 were conducted to verify the performance of spiral anchorage zone reinforcement for banded post-tensioning (PT) monostrands. With results, the compressive strength of spiral reinforcement was increased by about 20% than that of specimens with two horizontal steel bars and 8% than that of U-shaped bars. Advanced spiral reinforcement for corner increases compressive strength and can resist the spalling forces or fall-out effect at the corner by shear. The ratio of maximum load to amount of steel of the spiral reinforcement is about twice than that of U-shaped reinforcement. With increase of compressive strength capacity and improvement of constructability, the spiral reinforcement is considered to have advantages of promoting the performance of PT anchorage zone compared to conventional methods.

Evaluation of Shear Performance of Reinforced Concrete Beams for Varying Reinforcement Details of Web Opening (유공부 보강상세에 따른 철근콘크리트 유공 보의 전단 성능 평가)

  • Kim, Min-Jun;Lee, Bum-Sik;Kim, Dong-Whan;Kim, Hyeong-Gook;Lee, Yong-Jun;Kim, Kil-Hee
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.4
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    • pp.19-26
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    • 2018
  • This study evaluates the shear performance of reinforced concrete members with web opening reinforcement. A total of 4 reinforced concrete members with or without openings were cast then tested. The main variables investigated were with or without of web openings and with or without of web opening reinforcement, respectively. The proposed web opening reinforcement was a rectangle and rhombus-shaped spiral considering of construct ability. Test result showed that the proposed web reinforcement had improved shear capacity and ductility of the specimens. It was found that the web opening reinforcement proposed in this study had a positive effect on the shear strength and crack control of RC beams with web openings. In addition, it was confirmed that the analytical results by the current design codes underestimates the test results of the specimens with the proposed web opening reinforcement.

Evaluation of Shear Performance of RC Web Opening Beams According to the Shape of Web Opening Reinforcement (유공보강근의 형상에 따른 철근콘크리트 유공 보의 전단성능평가)

  • Kim, Min-Jun;Lee, Bum-Sik;Kim, Kil-Hee
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.25 no.5
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    • pp.76-85
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    • 2021
  • In this study, a shear experiment was conducted to evaluate the structural performance of RC members according to the shape of web opening reinforcement. For a total of 4 RC members specimens, the main variables were with or without web openings, with or without web opening reinforcement, and shape of web opening reinforcement, respectively. In this study, a spiral web opening reinforcement with a mixture of square and octagonal shapes was proposed and compared with the existing band type. As a result of the experiment, the specimen with the proposed web opening reinforcement showed that the shear capacity and the energy dissipation capacity increased compared to other specimens. It was confirmed that the web opening reinforcement proposed in this study had a positive effect on the shear performance and crack control of RC members with web openings.