• Title/Summary/Keyword: 콘크리트보

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Experimental Investigation of the Flexural Behavior of Polymer-modified Lightweight Aggregate Concrete One-Way Members (폴리머 개질 경량콘크리트 일방향 부재의 휨 거동에 관한 실험적 연구)

  • Byon, Eun-Hyuk;Kim, Min-Sook;Lee, Young-Hak;Kim, Hee-Cheul
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.23 no.5
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    • pp.551-557
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    • 2010
  • The purpose of this study is to estimate experimentally the flexural behavior, capacity and validity of existing regulation of net tensile strain in lightweight concrete beams and polymer modified lightweight concrete beams. One normal weight concrete beam and four lightweight concrete beams, three polymer modified lightweight concrete beams were constructed as same figure and attempted to evaluate the difference of strength and ductility in specimens of different net tensile strain in extreme tension steel. Test results are indicated in terms of load-deflection behavior and ductility index. As the value of net tensile strain increased, the flexural strength and stiffness of specimen decreased but ductility index increased in both of lightweight concrete beams and polymer modified lightweight concrete beams. It is considered that to achieve similar ductility index of normal weight concrete, net tensile strain in extreme tension steel should exceed 0.005 for lightweight concrete beam and polymer modified lightweight concrete beam.

Experimental Study on Improvement of Bond Performance of RC Beams with High-Strength Shear Reinforcement (고강도 전단철근을 사용한 철근콘크리트 보의 부착성능 향상에 관한 실험적 연구)

  • Kim, Sang-Woo;Kim, Do-Jin;Yoon, Hye-Sun;Baek, Sung-Cheol;Kim, Kil-Hee
    • Journal of the Korea Concrete Institute
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    • v.22 no.4
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    • pp.527-534
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    • 2010
  • This study presents a simple method to improve the bond performance of reinforced concrete (RC) beams having high-strength shear reinforcement. In general, the yield strength and the ratio of shear reinforcements are the main parameters governing the shear capacity of RC beams. The yield strength of shear reinforcement, however, has little influence on the bond capacity of RC beams. Therefore, a sudden bond failure of the members with high-strength shear reinforcement can occur before flexural failure. To estimate the structural performance of the proposed method, four RC beams were cast and tested. The main test parameters were the yield strength, ratio, and reinforcing types of shear reinforcements. The experimental results indicated that the proposed method was able to effectively improve the bond performance of RC beams with high-strength shear reinforcement.

Improvement and Evaluation of Seismic Performance for Reinforced Concrete Beam-Column Joints Using High Performance Embedded FRP (고성능 FRP를 활용한 철근콘크리트 보-기둥 접합부의 내진 성능 평가 및 개선)

  • Ha, Gee-Joo;Shin, Jong-Hack;Kang, Hyun-Wook
    • Journal of the Korea Concrete Institute
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    • v.23 no.3
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    • pp.385-392
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    • 2011
  • In this study, experimental research was carried out to evaluate and improve the seismic performance of reinforced concrete beam-column joint regions using strengthening materials (steel plate, carbon fiber sheet, and embedded carbon fiber rod) in existing reinforced concrete buildings. Six specimens of retrofitted beam-column joints are constructed using various retrofitting materials and tested for their retrofit performances. Specimens designed by retrofitting the beam-column joint regions (LBCJ series) of existing reinforced concrete building showed a stable mode of failure and an increase in load-carrying capacity due to the effect of crack control at the time of initial loading and confinement from retrofitting materials during testing. Specimens of LBCJ series, designed by the retrofitting of FRP in reinforecd beam-column joint regions increased its maximum load carrying capacity by 26~50% and its energy dissipation capacity by 13.0~14.4% when compared to standard specimen of LBCJC with a displacement ductility of 4.

Flexural Performance of Reinforced Concrete Beams with Recycled Aggregates Suffering from Sustained Load (지속하중을 경험한 철근콘크리트 보의 골재 종류에 따른 휨거동 특성)

  • Ji, Sang-Kyu;Yun, Hyun-Do;Kim, Sun-Woo;Lee, Eon-Young
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.11 no.5
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    • pp.135-143
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    • 2007
  • This paper presents results of an experimental study designed to investigate the effect of sustained load on the flexural performance of reinforced recycled aggregate concrete beams. In this experimental program, three beams with recycled aggregate replacement percentages(natural 100%, recycled coarse aggregate 100%, recycled fine aggregate 50%) were tested up to failure after sustained loading($0.5M_n$) for one year. The experimental results showed that reinforced concrete beams using recycled aggregate(water absorption : 1.86~3.64%) concrete showed the same flexural performance as that of natural aggregate concrete beam. Current the ACI code underestimated experimental obtained ultimate flexural strength of beams irrespective of usage of recycled aggregates.

Experimental Evaluation on Effective Moment of Inertia of Reinforced Concrete Simple Beams and Continuos Beams Considering Tension Stiffening Effect (인장증강효과를 고려한 철근콘크리트 단순보와 연속보의 유효 단면2차모멘트에 대한 실험적 검증)

  • Lee, Seung-Bae;Yoon, Hyeong-Jae;Kim, Kang-Su;Kim, Sang-Sik
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.285-288
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    • 2008
  • A model for the effective moment of inertia $I_{\epsilon}$ as expressed in Branson's equation, in which reduction of the flexural rigidity of RC beams due to cracking are aptly taken into accoun,t is presented. However, KCI Code isn`t considered tension stiffening as it is in debonding of reinforcing bar. Therefore, this equation need to set up suitable to our design Code. The experimental work consisted of casting and testing a total of 6 simply supported reinforced concrete beams and a total of 4 continuos reinforced concrete beams under two point concentrated loads. Main parameters are concrete strength, coverage, bond between concrete and reinforcing bars, are known as have an effect on deflection and tension stiffening. Every test beams had the same $250{\times}350$mm rectangular section, with a simply supported clear span of 4,400 mm and a continuos clear span of 6,500 mm. Comparison of the test results with values obtained using the KCI Code equation of the effective moment of inertia showed a noticeable difference.

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An Experimental Study on the Effective Strain of Reinforced Concrete Beams Strengthened by Fiber Reinforced Polymer (FRP로 보강된 철근콘크리트 보의 유효 변형률 예측에 대한 실험적 연구)

  • Hwang, Hyun-Bok;Lee, Jung-Yoon
    • Journal of the Korea Concrete Institute
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    • v.19 no.2
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    • pp.145-151
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    • 2007
  • The shear failure modes of FRP strengthened concrete beams are quite different to those of the beams strengthened with steel stirrups. When the beams are externally wrapped with FRP composites, many beams fail in shear due to concrete crushing before the FRP reaches its rupture strain. In order to predict the shear strength of such beams, the effective strain of the FRP must be blown. This paper presents the results of an experimental study on the performance of reinforced concrete beams externally wrapped with FRP composites and infernally reinforced with steel stirrups. The main parameters of the tests were FRP reinforcement ratio, the type of fiber material (carbon or glass) and configuration (continues sheets or strips). The experimentally observed effective strain of the FRP was compared with the strain calculated using a proposed method.

An Experimental Study on Corrosion Resistance of Cracked Concrete (균열 콘크리트에서의 부식저항성에 관한 실험적 연구)

  • Song, Ha-Won;Lee, Chang-Hong;Ann, Ki-Yong;Lee, Kewn-Chu
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.517-520
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    • 2008
  • In this study, corrosion resistance of steel in cracked-reinforced concrete was performed according to experimental method. Mixed design is OPC, 30% PFA, 60% GGBS and 10% SF, respectively. Moreover, corrosion resistance test was measured using ultra testing machine for 0.3mm crack induction. The corrosion resistance of blended concrete shows the results following OPC > 10%SF > 30% PFA > 60% GGBS after 60days curing. In case of mass loss test, embedded reinforcement in OPC concrete surveyed the minimum corrosion and appeared better corrosion resistance than blended concrete. As a result, corrosion resistance of sound concrete is higher than cracked concrete. Moreover, corrosion resistance of binary concrete is lower than OPC.

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해양환경에서의 콘크리트 보의 성능연구

  • Yang, In-Hwan;Kim, Gyeong-Cheol;Kim, Yeong-Jun
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2013.10a
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    • pp.261-263
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    • 2013
  • 해양환경에서의 아연코팅철근 콘크리트 보의 휨 성능 및 균열 특성 실험을 수행하였다. 또한, 보에서 발생하는 균열 및 파괴양상을 파악하였다. 그 결과, 해양환경에서의 콘크리트 부재의 피복두께를 기존 설계기준보다 작게 적용시켜도 부재에 발생하는 염해에 대한 내구성을 확보할 수 있으며, 아연코팅 철근의 적용은 일반철근 콘크리트 보다 내구성 측면에서 유리하다고 판단된다.

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Flexural Performance of Activated Hwangtoh Concrete Beam (활성 황토 콘크리트 보의 휨 성능)

  • Lee, Nam-Kon;Hwang, Hye-Zoo;Park, Hong-Gun
    • Journal of the Korea Concrete Institute
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    • v.22 no.4
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    • pp.567-574
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    • 2010
  • As a eco-friendly material, Hwangtoh(red clay) has been studied for a partial or complete replacement of portland cement. Most of existing studies focused on the mechanical properties of the Hwangtoh concrete including the compressive strength, drying shrinkage, creep. In the present study, the flexural capacity of the beams made with the Hwangtoh concrete was tested. One of the concrete tested consisted of activated Hwangtoh replacing 20% of the cement. The other consisted 100% activated Hwangtoh replacing all the cement. The simple beams were tested under two point static loading. The flexural strength, cracking moment, deflection, and ductility were compared with those of the beams made with ordinary portland cement concrete.

Deformability of RC Beam-Column Assembles (철근콘크리트 보-기둥 접합부의 연성능력)

  • Lee, Jung-Yoon
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.193-196
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    • 2008
  • This paper proposes a method to predict the ductility capacity of reinforced concrete beam-column joints failing in shear after the formations of plastic hinges at both ends of the adjacent beams. The current design code divides joints into two categories: Type 1 for structures in non seismically hazard area and Type 2 in seismically hazard area. While there are many researches related to joint shear strength in Type 1, those in regard to joint ductility capacity of Type 2 are scarce. This paper classified the ductility capacity of beam-column joints into column, joint panel, and beam deformability. Since a brittle failure such as shear or bond failure in the columns must be avoided, column deformability was calculated by elastic analysis. The plastic hinges of the adjacent beams affect joint deformability. Therefore, the prediction of joint deformability was calculated with consideration to the degradation of the diagonally compressed concrete due to the strain penetration.

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