• Title/Summary/Keyword: 기둥보강

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Seismic Performance of Circular RC Columns Retrofitted Using Ductile PET Fibers (고연성 PET 섬유로 보강된 철근콘크리트 원형 기둥의 내진성능)

  • Vachirapanyakun, Sorrasak;Lim, Myung-Kwan;Choi, Dong-Uk
    • Journal of the Korea Concrete Institute
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    • v.28 no.3
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    • pp.289-298
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    • 2016
  • An experimental research was performed using fibers for the purpose of retrofitting existing reinforced concrete circular columns. Glass fiber (GF) and polyethylene terephthalate (PET) were used as well as combined GF+PET (HF). PET has high tensile strength (over 600 MPa) and high ductility (about 15%), but has very low elastic modulus (about 1/6 of GF). A total of four columns was tested against laterally applied reverse cyclic load: control column, GF-, PET-, and HF-strengthened columns. All columns retrofitted using fibers demonstrated improved moment capacity and ductility. Moment capacity of GF-, PET-, and HF-strengthened columns was 120%, 107%, and 120% of the control column, respectively. Drift ratio of all retrofitted columns also increased by 63 ~ 83% over the control column. The final failure mode of the control column was main bar buckling. The final failure mode of the GF- and HF-strengthened columns was GF rupture while that of the PET-strengthened column was main bar rupture in tension. No damage was observed for PET at the ultimate stage due to excellent strain capacity intrinsic to PET. Current test results indicate that PET can be effectively used for seismic retrofit of RC columns. It is noted that the durability characteristics of PET needs to be investigated in the future.

The Experiment and Design Formula of Rectangular CFT Columns Reinforced by Carbon Fiber Sheets (탄소섬유쉬트로 보강된 각형 CFT기둥의 실험 및 설계식)

  • Park, Jai-Woo;Chung, Sung-Hun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.11 no.10
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    • pp.4024-4030
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    • 2010
  • Axial load tests and cyclic load tests for FRP reinforced rectangular CFT columns were carried out The main parameters were width-thickness ratio of a steel tubeand FRP layer numbers for the axial load tests and were concrete strength and FRP layer numbers for cyclic load tests. The maximum strength and ductility capacity were compared between the current CFT columns and the FRP reinforced CFT columns. Finally, the axial design formulas were presented for the FRP reinforced CFT columns.

Retrofit Design of RC Column by Displacement-Based-Design Method (변위기반설계법에 의한 철근콘크리트 기둥의 보강설계)

  • Lim, Cheong-Kweon;Kwon, Min-Ho;Ha, Keum-Hee;Kim, Jin-Sup
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.6
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    • pp.2804-2811
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    • 2012
  • In this study, It is developed a retrofitting procedure of RC column with rectangular section to archive the target displacement at failure. Nonlinear behavior of the column is considered as the equivalent linear system. First, target displacement is determined, and then elastic displacement spectrum is constructed to estimate the equivalent natural vibration period of the SDOF system. After natural vibration period is determined, required strength is calculated using secant stiffness based on the mass of system. In accordance with, obtained force-displacement relationship through non-linear fiber based section analysis, retrofit design was carried out to meet required strength. As a result, retrofitted RC column can confirm that the improved seismic performance. It is observed that the proposed design procedure can be applicable to seismic retrofitting design of columns.

Confinement Effects of High Strength Reinforced Concrete Tied Columns (고강도 철근콘크리트 띠철근 기둥의 구속효과)

  • 신성우;한범석
    • Journal of the Korea Concrete Institute
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    • v.14 no.4
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    • pp.578-588
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    • 2002
  • An experimental study was conducted to investigate the effectiveness of transverse reinforcement in reinforced concrete tied columns subjected to monotonically increasing axial compression. Eighteen large-scale columns(260$\times$260$\times$1200 mm) were tested. Effects of main variables such as the concrete compressive strength, the tie configuration, the transverse reinforcement ratio, the tie spacing, and the spatting of the concrete cover were considered. High-strength concrete columns under concentric axial loads show extremely brittle behavior unless the columns are confined with transverse reinforcement that can provide sufficiently high lateral confinement pressure There is a consistent decrease in deformability of column specimen with increasing concrete strength. Test results were compared with the previous confinement model such as modified Kent-Park, Sheikh-Uzumeri, Mander, and Saatcioglu-Razvi model. The comparison indicates that many previous models for confined concrete overestimate or underestimate the ductility of confined concrete.

Evaluation of Concrete Structures Considering Reinforcing Bars in Columns (기둥의 보강철근을 고려한 콘크리트 구조물의 거동 평가)

  • Song, Hyung-Soo;Gwon, Ji-Youn;Cha, Hee-Youn;Min, Chang-Shik
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.289-292
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    • 2008
  • In this study, we interpreted 20 story building by applying the modified modulus of elasticity considering the reinforcing steel proposed in previous literature, and analyzed the movement of the structure according to axial reinforcing steel ratio and lateral reinforcing steel volume ratio. Additionally, we tried to get the result similar to the actual movement considering the order of the construction by performing the analysis by construction stage. Finally, we tried to reduce the section of the column through the analysis considering the reinforcing steel of the column. When interpreting the 20 story building considering the reinforcing steel in the columns, we can reduce the column members up to 4.94% comparing to the general analysis. If we do the same for each construction stage, it is analyzed that we can reduce up to 19%.

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Steel Jacketing Method without Grouting for RC Columns (그라우팅이 필요 없는 RC기둥 강판보강 기법)

  • Choi, Eun Soo;Cho, Sung Chul;Chung, Young Soo;Cho, Baik Soon
    • Journal of Korean Society of Steel Construction
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    • v.20 no.1
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    • pp.55-65
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    • 2008
  • This study introduced a new method to retrofit RC columns with lap splice that do not have enough ductility during an earthquake. The new method used mechanical external pressure and split steel plates around the RC columns. The introduced method does not require grouting the gap between jacket and concrete surface. In this study, 45 concrete cylinders were manufactured with varyingstrengths and part of them was retrofitted with split steel jackets under a lateral confining stress. The effect of the new method was verified by comparing the results from the compressive tests of retrofitted and unretrofitted cylinders. The steel jacket that was built following the new method showed good results of increasing the compressive strength and ductility of concrete cylinders. The thicker steel jackets showed larger compressive strength, however, the ductility at failure depends on their welding quality.

Cyclic Responses of Steel Reinforced ECC Column under Reversed Cyclic Loading Conditions (철근 보강된 ECC 기둥의 반복하중에 대한 이력거동)

  • Hyun, Jung-Hwan;Shim, Young-Heung;Bang, Jin-Wook;Kim, Yun-Yong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.19 no.4
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    • pp.75-82
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    • 2015
  • In this study, experimental research was carried out to evaluate steel reinforced ECC (Engineered Cementitious Composites) column, which exhibits excellent crack control property and highly ductile behavior. Ordinary portland cement and high volume fly ash were used as binding materials in the mixture proportions for the purpose of achieving a high level of multiple cracking property with the tightly controlled crack width. To compare with the cyclic behavior of steel reinforced ECC column specimen, a conventional reinforced concrete column was prepared and tested under reversed cyclic loading condition. Based on the cyclic load test, ECC column exhibited higher cyclic behavior, compared to the conventional RC column, in terms of load carrying capacity and energy dissipation capacity.

Evaluation of Lateral Strength and Ductility of Velcro Reinforced RC Columns with Finite Element Analysis (유한요소해석을 통한 벨크로로 보강된 RC 기둥의 횡방향 강도 및 연성 능력 평가)

  • Kim, Sang-Woo;Kim, Kyeong-Min;Kim, Geon-Woo;Lee, Su-Young;Kim, Jin-Sup
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.25 no.4
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    • pp.12-19
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    • 2021
  • Recently, with frequent earthquakes around the world, research on seismic design and seismic reinforcement of reinforced concrete facilities has been actively conducted from earthquakes. In particular, columns, which are compressed members of reinforced concrete structures, are vulnerable to lateral forces caused by earthquakes, so an appropriate seismic reinforcement method is required. Therefore, this study intended to develop Velcro seismic reinforcement method that is quick and easy to construct. For the development of Velcro seismic reinforcement, the adhesion and tensile strength of the existing industrial velcro was improved. A direct tensile test was also conducted to compare the tensile performance of the newly-developed velcro seismic reinforcement to industrial one. In addition, numerical analysis was performed to predict the seismic performance of RC columns reinforced by industrial and newly-developed velcro. Based on the analysis results, the strength and ductility of the non-seismic and velcro-reinforced RC column were reviewed. The analysis confirmed that both the strength and ductility of non-seismic RC columns reinforced by industrial and newly-developed velcro increased, but the seismic performance of the newly-developed Velcro reinforcement is better than that of industrial velcro.

Structural Characteristics of Reinforced Concrete Beam-Column Joints Repaired and Restrengthening (재보수-보강된 철근콘크리트 보-기둥 접합부의 구조특성)

  • Cho, Chang-Ho;Kim, Jeong-Sup
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.7 no.2
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    • pp.231-238
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    • 2003
  • Reinforced concrete buildings damaged by earthquake which can be reused can ensure the stability in its structure by repair-restrengthening, but when such a repair-restrengthening is conducted inappropriately or its structural strength is greatly reduced by earthquake again, it should have repair-restrengthening. This study selects beam-column joints which are vulnerable to earthquake as the object of experiment, performs repair-restrengthening after applying the first and the second dynamic loading to the objects of experiment, examines the capacity of restrengthening according to structural characteristics and loading velocity and verifys the validity of repair-restrengthening.

New Technique on the Improvement of Earthquake-Resistant Performance for the Retrofitting of Existing Reinforced Concrete Beam-Column Joints (철근콘크리트 보-기둥 접합부의 내진성능 개선 보강 신기술)

  • 하기주
    • Journal of the Earthquake Engineering Society of Korea
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    • v.8 no.2
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    • pp.73-81
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    • 2004
  • In this study, experimental research was carried out to improve earthquake-resistant performance for the retrofitting of reinforced concrete beam-column joints using carbon fiber materials in existing reinforced concrete building. Six reinforced concrete beam-column joints were constructed and tested to evaluate the retrofitting effect of test variables, such as the retrofitting materials and retrofitting region(plastic hinge, beam-column joint) under load reversals. Test results show that retrofitting specimen(RPC-CP2, RPC-CR, RJC-CP, RJC-CR), using new materials(carbon fiber plate, carbon fiber rod and carbon fiber sheet), designed by the improvement of earthquake-resistant performance and ductility, attained more load-carrying capacity and stable hysteretic behavior.