• Title/Summary/Keyword: 연성능력

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Displacement Ductility Ratio of Reinforced Concrete Bridge Piers with Lap-splices (주철근 겹침이음 비율에 따른 RC교각의 연성능력 평가)

  • Park, Kwang-Soon;Ju, Hyeong-Seok;Shin, Hyun-Mock;Kim, Moon-Kyum
    • Journal of the Earthquake Engineering Society of Korea
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    • v.12 no.6
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    • pp.1-12
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    • 2008
  • As internal and external seismic experiment results, the seismic performance of RC bridge piers is largely dependent on the ratio of lap-spliced bars to all longitudinal reinforcing bars in plastic hinge regions, and confining effects of transverse reinforcements. Capacity and displacement ductility of non-seismically designed existing RC piers are reduced by lap splices in plastic hinge regions. The provision for the lap splice of longitudinal reinforcing bars was not specified in KBDS (Korean Bridge Design Specifications) before the implementation of 1992 seismic design code, but the ratio of lap-spliced bars to all longitudinal reinforcing bars in plastic hinge regions is restricted to 50% in the 2005 version of KBDS. This paper presents a seismic assessment of RC piers at lap-splicing ratios of 0%, 50%, and 100%. Through a comparison of experimental and analytic results of RC piers, we introduce an appropriate ultimate strain of confined concrete in plastic hinge regions with lap-splices, and propose a method for estimating displacement ductility ratios of non-seismically designed existing RC piers using fiber element analysis.

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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Analytical Study on Inelastic Behavior and Ductility Capacity of Reinforced Concerte Bridge Columns Subjected to Seismic Load (지진하중을 받는 철근콘크리트 교각의 비탄성 거동 및 연성능력에 관한 해석적 연구)

  • 김태훈;유영화;신현목
    • Journal of the Earthquake Engineering Society of Korea
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    • v.4 no.4
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    • pp.37-51
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    • 2000
  • 이 연구는 지진 시 철근콘크리트 교각의 비탄성 거동 및 연성능력을 해석적으로 파악하는데 그 목적이 있다. 재료적 비선형성에 대해서는 균열 콘크리트에 대한 인장, 압축, 전단모델과 콘크리트 속에 있는 철근 모델을 조합하여 고려하였다. 이에 대한 콘크리트의 균열 모델로서의 분산균열모델을 사용하였다. 두께가 서로 다른 부재간의 접합부에 단면강성이 급변하기 때문에 생기는 국소적인 불연속변형을 고려하기 위한 경계면 요소를 도입하였다. 또한, 축방향철근의 유무 및 그 양 등에 따른 구속효과를 적절히 표현할 수 있는 해석 모델을 개발하였다. 본 연구에서는 철근콘크리트 교각의 비탄성 거동 및 연성 능력의 파악을 위해 제안한 해석기법을 신뢰성 있는 연구자의 실험결과와 비교하여 그 타당성을 검증하였다.

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Strength and Ductility of Steel Fiber Reinforced Composite Beams without Shear Reinforcements (전단보강근이 없는 강섬유 보강 합성보의 강도 및 연성 능력)

  • Oh, Young-Hun;Nam, Young-Gil;Kim, Jeong-Hae
    • Journal of the Korea Concrete Institute
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    • v.19 no.1
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    • pp.103-111
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    • 2007
  • Experimental study was carried out to investigate the structural performance of composite beams with steel fiber concrete and angle. For this purpose, seven specimens composed of two RC beams with or without steel fiber and five composite beams with steel fiber and angle were constructed and tested. All specimens had no web shear reinforcement. Main variables for the specimens were tensile reinforcement ratio and fiber volume fraction. Based on the test results, structural performance such as strength, stiffness, ductility and energy dissipation capacity was evaluated and compared with the predicted strength. The prediction of flexure and shear strength gives a good relationship with the observed strength. The strength, ductility and energy dissipation capacity are increased, as the fiber volume fraction is increased. Meanwhile, high tensile reinforcement ratio resulted in the reduction of ductility and energy dissipation capacity for the composite beams.

Effect of Tension, Compression and Lateral Reinforcement In Ductility Ratio in RC Flexural Members (철근콘크리트 휨 부재에서 인장, 압축 및 횡보강근이 연성률에 미치는 효과)

  • 연규원;박찬수
    • Journal of the Korea Concrete Institute
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    • v.13 no.6
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    • pp.553-560
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    • 2001
  • The ductility capacity should be estimated for inelastic analysis and design of reinforced concrete flexural members. Therefore, to estimate the ductility capacity, the model of moment-curvature relationship of reinforced concrete flexural member is assumed in this study. The curvature, rotation, and displacement(deflection) of reinforced concrete cantilever beams are analyzed and tested. The analytical results are compared with the test results. According to the analytical and test results, the assumed model of moment-curvature relationship in this study is adequate in flexural analysis of reinforced concrete members because the analytical results are well agreed with the test results, and it is resonable to express the ductility capacity in the rotation or displacement ductility, Because the curvature ductility is the limited index in a certain section. It is investigated that the ductility capacity is proportional to lateral reinforcement and compression reinforcement and inversely proportional to tension reinforcement.

An Experimental Study on the Ductility Capacity of Reinforced High Performance Concrete Beams (고성능 철근콘크리트 보의 연성능력에 관한 실험적 연구)

  • 김용부;고만영;오명석
    • Magazine of the Korea Concrete Institute
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    • v.10 no.3
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    • pp.117-124
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    • 1998
  • 본 연구는 고성능 철근콘크리트 보의 연성능력에 관한 실험이다. 실험변수로는인장철근비( )와 하중재하형태(1점가력과 2점가력)가 있다. 콘크리트의 실린더 압축강도가 800-900㎏/㎠, 슬럼프 20∼25㎝ 및 슬럼프 플로우가 60∼70㎝인 고성능 철근콘크리트 보의 휨 실험 결과,고성능 콘크리트는 일반강도 콘크리트보다 취성적인 성질을 나타냈으며, 이러한 성질은 고성능 콘크리트의 연성능력을 감소시켰다. 고성능철근콘크리트의 경우 등가응력블록 변수는 MacGregor블록이나 New Zealand 규준을 사용하는 것이 바람직하다. 또한, 극한 곡률을 구할때는 cu= 0.0042값을 사용하는 것이 타당하다고 사료된다. 고성능 철근콘크리트 보의 경우, 현재 ACI 규준의 철근비에서 허용하는 2 및 4 이상의 연성지수 확보는 각각 '/ 0.30 범위에서 정적하중 상태의 경우 철근비가 - '=0.60 b이하에서 가능하고 휨 부재의 모멘트 재분배를 위한 경우는 철근비를 - '=0.33 b이하로 낮추어야 할 것으로 판단된다.

Strength and Deformation Characteristics of Steel Fiber Reinforced Columns (강섬유 보강 기둥의 강도 및 변형 특성)

  • 장극관;이현호;양승호
    • Journal of the Korea Concrete Institute
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    • v.14 no.1
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    • pp.49-57
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    • 2002
  • As composite materials, the addition of steel fiber with concrete significant)y improves the engineering properties of structural members, notably shear strength and ductility. Flexural strength, fatigue strength, and the capacity to resist cracking are also enhanced. Especially the strengthening effect of steel fiber in shear is to prevent the brittle shear failure. In this study, shear-strengthening effect of steel fiber in RC short columns were investigated from the literature surveys and 10th specimem's member test results. From the test results, following conclusions can be made; the maximum enhancement of shear-strengthening effect can be achieved at about 1.5 % of steel fiber contents, shear strength and ductility capacity were improved remarkably in comparison to stiffness and energy dissipation capacity in steel fiber reinforced concrete.

Evaluation of Seismic Performance for Building Structures by Hysteresis Model of Elements (부재의 이력모델에 따른 건축구조물의 내진성능 평가)

  • Han, Duck-Jeon;Ko, Hyun
    • Journal of Korean Association for Spatial Structures
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    • v.9 no.4
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    • pp.73-80
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    • 2009
  • It is very important that predict the inelastic seismic behavior exactly for seismic performance evaluation of a building in the performance based seismic design. But, it is difficulty that predict the building behavior of actual and exact in simplified load-deformation relation of structural material and members. In this study, system ductility and story ductility capacity of building structure used to the Backbone hinge Model are estimated and compared considering the characteristics of load-deformation relation of structural material and members. Analyses results, bilinear hinge model has lower system ductility and story ductility demands than those of backbone hinge model.

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Ductility Capacity of Shear-Dominated Steel Plate Walls (전단지배 강판벽의 연성능력)

  • Park, Hong Gun;Choi, In Rak;Jeon , Sang Woo;Kim, Won Ki
    • Journal of Korean Society of Steel Construction
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    • v.18 no.4
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    • pp.457-468
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    • 2006
  • An experimental study was performed to investigate the maximum energy dissipation and the ductility capacity of shear-dominated steel plate walls with thin web plates. Three specimens of three-story plate walls with thin web plates were tested. The parameters for the test specimens were the aspect ratio of the web plate and the shear strength of the column. A concentrically braced frame and a moment-resisting frme were a also tested for comparison. The steel plate walls exhibited much better ductility and energy dissipation capacity than the concentrically braced frame and the moment-resisting frame. The results showed that unlike other structural systems, the sh as well as strength, and can therefore be used as an effective earthquake-resisting system. A method of predicting the energy dissipation capacity of a steel plate wall was proposed.

Inelastic Behavior and Ductility Capacity of Reinforced Concrete Frame Subjected In Cyclic Lateral Load (반복 휭하중을 받는 철근콘크리트 골조의 비탄성 거동 및 연성능력)

  • 김태훈;김운학;신현목
    • Journal of the Korea Concrete Institute
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    • v.14 no.4
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    • pp.467-473
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    • 2002
  • The purpose of this study is to investigate the inelastic behavior and ductility capacity of reinforced concrete frame subjected to cyclic lateral load and to provide result for developing improved seismic design criteria. A computer program named RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology) for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. The strength increase of concrete due to the lateral confining reinforcement has been taken into account to model the confined concrete. In boundary plane at which each member with different thickness is connected local discontinuous deformation due to the abrupt change in their stiffness can be taken into account by introducing interface element. The effect of number of load reversals with the same displacement amplitude has been also taken into account to model the reinforcing steel. The proposed numerical method for the inelastic behavior and ductility capacity of reinforced concrete frame subjected to cyclic lateral load is verified by comparison with reliable experimental results.