• Title, Summary, Keyword: 프리스트레스트 콘크리트 보

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A Computational Platform for Nonlinear Analysis of Prestressed Concrete Deep Beams (프리스트레스트 콘크리트 깊은 보의 비선형해석을 위한 전산플랫폼)

  • Kim, Tae-Hoon;Kim, Young-Jin;Shin, Hyun-Mock
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.734-737
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    • 2010
  • 이 연구에서는 프리스트레스트 콘크리트 깊은 보의 비선형해석을 위한 전산플랫폼을 개발하였다. 프리스트레스트 콘크리트 깊은 보의 전단거동을 정확하게 파악하고 합리적이면서 경제적인 설계기준의 개발을 위한 자료를 제공하는데 그 목적이 있다. 재료적 비선형성에 대해서는 균열콘크리트에 대한 인장, 압축, 전단모델과 콘크리트 속에 있는 철근모델을 조합하여 고려하였다. 사용된 부착 또는 비부착 텐던요소는 유한요소법에 근거하며 프리스트레스트 콘크리트 부재의 콘크리트와 텐던의 상호작용을 구현할 수 있다. 이 연구에서는 프리스트레스트 콘크리트 깊은 보의 전단거동을 파악하기 위해 제안한 해석기법을 신뢰성 있는 연구자의 실험 결과와 비교하여 그 타당성을 검증하였다.

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Flexural Behavior of Prestressed Dual Concrete Beams (프리스트레스트 이중 콘크리트 보의 휨 거동 해석)

  • Park Tae-Hyo;Yun Sung-Hwan;Yun Hee-Dae
    • Journal of the Korea Concrete Institute
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    • v.17 no.3
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    • pp.445-454
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    • 2005
  • Cracks due to low tensile strength in prestressed concrete (PC) beams may decrease rigidity and structural performance, resulting in excessive deflection. In an effort to solve this problem, in this research, prestressed dual concrete (PDC) has been proposed, consisting of normal strength concrete in compression zone, and high performance steel fiber reinforced concrete(HPSFRC) with a partial depth in tensile zone. Three PDC beams with different depths of HPSFRC and two PC beams were cast for experiments. Analytical models at each stage, i.e., precracking, postcracking, and ultimate, were proposed for analysis of flexural behavior in PDC beams. The experimental results agree well to the analytical ones. Crack formation and its propagation are controlled by the HPSFRC in PDC beams. The initial cracking and service limit loads are increased along with the load carrying capacity and flexural stiffness.

Shear-tendon Rupture Failure of Concrete Beams Prestressed with FRP Tendons (FRP를 사용한 프리스트레스트 콘크리트 보의 전단 텐던 파괴)

  • 박상렬
    • Magazine of the Korea Concrete Institute
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    • v.10 no.1
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    • pp.133-141
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    • 1998
  • FRP는 비부식성 및 고강도의 뛰어난 성질에도 불구하고 콘크리트 구조에 사용하는 데 있어서 소성의 결핍 및 낮은 전단강도와 같은 몇가지의 기술적인 단점을 가지고 있다. 특히 이 두가지 성질은 프리스트레스트 콘크리트보에 있어서 다우얼 작용이 일어나는 전단균열 단면에서와 같이 인장과 전단의 복합효과가 일어날 때 텐던의 조기 파괴를 일으키기 쉽다. 본 논문에서는 탄소 FRP연선을 사용한 프리스트레스트 콘크리트보에서의 텐던파열에 의한 전단파괴를 연구하였다. 전단시험 결과에 의하면 전단 텐던 파괴는 FRP를사용한 프리스트레스트 보에서만 일어나는 유일한 파괴형식으로 보의 전단강도를 저감시키는 것으로 확인되었다. 이러한 전단 텐던 파괴 과정을 규명하기 위하여 다우얼 시험을 실시하고 최초로 실용적인 시험장치 및 과정을 소개하였다. 다우얼 시험 결과에 의하면 FRP 연선은 인장과 전단의 상호작용에 의해 Tsai-Hill 파괴 기준에 따라 파괴되었다.

Finite Element Analysis to Determine Shear Behavior of Prestressed Concrete Deep Beams (유한요소법을 이용한 프리스트레스트 콘크리트 깊은 보의 전단 거동 해석)

  • Jin, Hui-Jing;Kim, Han-Soo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.32 no.3
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    • pp.165-172
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    • 2019
  • In this study, the shear strength of prestressed concrete deep beams is predicted using finite element analysis, and the variation in the shear strength according to the degree of prestressing is investigated. Numerical analysis results are compared with results obtained by the strut-and-tie model and associated experiments. Numerical analyses are performed on prestressed concrete deep beams with different values of concrete strength, effective prestress, ratio of tensile reinforcement, and shear span to effective depth ratio. The shear strength predicted by the numerical analysis is similar to the experimental value obtained, with an error of less than 5%. However, the strut-and-tie model highly overestimated the shear strength of prestressed concrete deep beams with a concentrated loading area. The ultimate shear capacity of prestressed concrete deep beams increased linearly with increasing prestresss applied to the tendon.

Fatigue Behavior of Prestressed Concrete Beams Using FRP Tendons (FRP 긴장재를 이용한 프리스트레스트 콘크리트 보의 피로 거동)

  • Kim, Kyoung-Nam;Park, Sang-Yeol;Kim, Chang-Hoon
    • Journal of the Korea Concrete Institute
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    • v.23 no.2
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    • pp.135-144
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    • 2011
  • Recently, researches about fiber reinforced polymer (FRP) which has excellent durability, corrosion resistance, and tensile strength as a substitution material to steel tendon have been actively pursued. This study is performed to examine FRP tendon used prestressed beam's safety under service load. The specimen was a prestressed concrete beam with internal bonded FRP tendon. In order to compare the member fatigue capacity, a control specimen of a prestressed concrete beam with ordinary steel tendon was tested. A fatigue load was applied at a load range of 60%, 70%, and 80% of the 40% ultimate load, which was obtained though a static test. The fatigue load was applied as a 1~3 Hz sine wave with 4 point loading setup. Fatigue load with maximum 1 million cycles was applied. The specimen applied with a load ranging between 40~60% did not show a fatigue failure until 1 million cycles. However, it was found that horizontal cracks in the direction of tendons were found and bond force between the tendon and concrete was degraded as the load cycles increased. This fatigue study showed that the prestressed concrete beam using FRP tendon was safe under a fatigue load within a service load range. Fatigue strength of the specimen with FRP and steel tendon after 1 million cycles was 69.2% and 59.8% of the prestressed concrete beam's static strength, respectively.

An Indeterminate Strut-Tie Model for Prestressed Concrete Beams (프리스트레스트 콘크리트 보의 부정정 스트럿-타이 모델)

  • Chae, Hyun Soo;Yun, Young Mook
    • Journal of The Korean Society of Civil Engineers
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    • v.35 no.4
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    • pp.801-814
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    • 2015
  • In this study, a statically simple indeterminate strut-tie model is proposed for the rational analysis and design of simply supported prestressed concrete beams by reflecting all characteristics of nonlinear structural behavior and load transfer mechanisms. In addition, a load distribution ratio that allows to transform the proposed indeterminate strut-tie model to a determinate model is also suggested to help structural designers conduct the structural analysis and design of simply supported prestressed concrete beams by using the strut-tie model method of current design codes. For verifying of the validity of the proposed model and load distribution ratio, the ultimate strengths of 47 simply supported prestressted concrete beams tested to failure were estimated and the results were compared with those by the strut-tie model methods of current design codes.

Theoretical Assessment of Flexural Strength of Unbonded FRP Prestressed Concrete Beams (비부착 FRP 프리스트레스트 콘크리트보의 휨내력 이론 산정)

  • Heo, Seo-Young;Lee, Cha-Don;Jeong, Sang-Mo
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.1045-1048
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    • 2008
  • Fiber reinforced polymer (FRP) usually exhibits inherent brittleness under tensile stress. Application of FRP tendons to concrete beam leads to undesirable flexural behavior due to limited ductility compared to prestressed concrete beam with steel tendons. It has been experimentally observed that partial improvement of flexural behavior can be achieved by releasing FRP tendons' strain by unbonding FRP tendons. In order to estimate and apply the degree of improvement to the design, reasonable yet practical model predicting flexural strength as well as overall flexural behavior of unbonded FRP prestressed concrete beam is needed. In this study, an elaborated model in describing curvature distributions and flexural strength at ultimate stage of unbonded FRP tendons is described. There have been close agreements on the flexural strength of the FRP prestressed concrete beam between the predictions by nonlinear computer program and by the model.

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Analytical Study on the Shear Behavior of Prestressed Concrete Deep Beams (프리스트레스트 콘크리트 깊은 보의 전단거동에 관한 해석적 연구)

  • Kim, Tae-Hoon;Kim, Young-Jin;Shin, Hyun-Mock
    • Journal of the Korea Concrete Institute
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    • v.22 no.4
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    • pp.511-517
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    • 2010
  • The purpose of this study is to investigate the shear behavior of prestressed concrete deep beams and to provide the data for development of improved design criteria. The accuracy and objectivity of the assessment process may be enhanced by the use of sophisticated nonlinear finite element analysis program. Hence, in this study, the computer program, named RCAHEST (reinforced concrete analysis in higher evaluation system technology), was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. A bonded or unbonded tendon element based on the finite element method, that can represent the interaction between tendon and concrete of prestressed concrete member, is used. The proposed numerical method for the shear behavior of prestressed concrete deep beams is verified by comparing the analytical results with test data by others.

Evaluation of Shear Design Provisions for Reinforced Concrete Beams and Prestressed Concrete Beams (철근콘크리트 보와 프리스트레스트 콘크리트 보의 전단설계기준에 대한 고찰)

  • Kim Kang-Su;Kim Sang-Sik
    • Journal of the Korea Concrete Institute
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    • v.17 no.5
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    • pp.717-726
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    • 2005
  • Shear test data have been extracted from previous experimental research and compiled into a database that may be the largest ever made. In this paper, the shear database (SDB) was used for evaluating shear design provisions for both reinforced concrete (RC) beams and prestressd concrete (PSC) beams. A discussion on the use of the results of this evaluation related to calibration and strength reduction factor for the shear design provisions was also provided. It was observed that the shear design provisions did not provide good predictions for RC members and gave very poor predictions especially for RC members without shear reinforcement. On the other hand, the limit on shear strength contributed by transverse reinforcement was observed to be lower than necessary. The shear design provisions gave very unconservative results for the large RC members (d>700mm) without shear reinforcement having light amount of longitudinal reinforcement $(\rho_w<1.0\%)$. However, for PSC members the shear design provisions gave a good estimation of ultimate shear strength with a reasonable margin of safety. Despite of a large difference of accuracy in prediction of shear strength for RC members and PSC members, the shear design provisions used a same shear strength reduction factor for these members. As a result, the shear design provisions did not provide a uniform factor of safety against shear failure for different types of members.

Optimization for the Least Weight, Precast Prestressed Gerber′s U-Beams (최소자중 프리캐스트 프리스트레스트 게르버 U형보의 최적화)

  • 박현석;김인규;유승룡
    • Journal of the Korea Concrete Institute
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    • v.14 no.3
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    • pp.373-381
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    • 2002
  • The cost on transmission and erection of the precast prestressed concrete members largely depends on the weight of them. Optimum process is performed on a U-beam section to control the prestressing force, to reduce the self-weight, and to meet the required strength and stability. The strength, deflection, and concrete stress at the top and bottom of the section considered are required to check according to each construction step in this process. The weight of the original rectangular concrete beam could be reduced up to 39∼50% from this method. Two full scale prototype U-beams were proposed and tested in this study. It was found that the U-beams in the test showed good performance in strength and serviceability within the limits of ultimate strength design method.