• Title/Summary/Keyword: concrete strut

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Design of Anchorage Zone in Prestressed Concrete Structure Using Nonlinear Strut and Tie Model (비선형 스트럿-타이 모델에 의한 PC 구조물의 정착부 설계)

  • 배한옥;변근주;송하원
    • Proceedings of the Korea Concrete Institute Conference
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    • 1997.04a
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    • pp.392-397
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    • 1997
  • In this paper, design and analysis of anchorage zone in prestressed concrete structure using nonlinear strut and tie model is presented. Nonlinear strut and tie model is an analysis and design model which constructs strut and tie model based on nonlinear analysis considering the nonlinear behavior of concrete. Based on the nonlinear strut and tie model, the analysis and design are performed for the anchorage zone having singular concentric tendons, singular eccentric tendons and multiple tendons, respectively. For verification of the model, comparisons are made with experimental results as well as results by linear strut and tie models. from the comparisons, it is shown that the design of the anchorage zone by the nonlinear model is still economical without loosing the degree of safety and the prediction of the ultimate load by the nonlinear model gives better accuracy than by the linear one.

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Nonlinear Strut-Tie Model Approach in Pre-tensioned Concrete Deep Beams (높이가 큰 프리텐션 콘크리트 보에서의 비선형 스트럿-타이 모델 방법)

  • 윤영묵;이원석
    • Proceedings of the Korea Concrete Institute Conference
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    • 2000.04a
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    • pp.847-852
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    • 2000
  • This paper presents an evaluation of the behavior and strength of two pre-tensioned concrete deep beams tested to failure with using the nonlinear strut-tie model approach. In the approach, the effective prestressing forces represented be equivalent external loads are gradually introduced along its transfer length in the nearest strut-tie model joints, the friction at the interface of main diagonal shear cracks is modeled by diagonal struts along the direction of the cracks in strut tie-model, and additional positioning of concrete ties a the place of steel ties is incorporated. Through the analysis of pre-tensioned concrete deep beams, the nonlinear strut-tie model approach proved to present effective solutions for prediction the essential aspects of the behavior and strength of pre-tensioned concrete deep beams.

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Direct Inelastic Design of Reinforced Concrete Members Using Strut-and-Tie Model (스트럿-타이 모델을 이용한 철근콘크리트 부재의 직접 비탄성 설계)

  • Eom, Tae-Sung;Park, Hong-Gun
    • Journal of the Korea Concrete Institute
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    • v.20 no.3
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    • pp.345-356
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    • 2008
  • In the previous study, direct inelastic strut-and-tie model (DISTM) was developed to perform inelastic design of reinforced concrete members by using linear analysis for their secant stiffness. In the present study, for convenience in design practice, the DISTM was further simplified so that inelastic design of reinforced concrete members can be performed by a run of linear analysis, without using iterative calculations. In the simplified direct inelastic strut-and-tie model (S-DISTM), a reinforced concrete member is idealized with compression strut of concrete and tension tie of reinforcing bars. For the strut and tie elements, elastic stiffness or secant stiffness is used according to the design strategy intended by engineer. To define the failure criteria of the strut and tie elements, concrete crushing and reinforcing bar fracture were considered. The proposed method was applied to inelastic design of various reinforced concrete members including deep beam, coupling beam, and shear wall. The design results were compared with the properties and the deformation capacities of the test specimens.

New strut-and-tie-models for shear strength prediction and design of RC deep beams

  • Chetchotisak, Panatchai;Teerawong, Jaruek;Yindeesuk, Sukit;Song, Junho
    • Computers and Concrete
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    • v.14 no.1
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    • pp.19-40
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    • 2014
  • Reinforced concrete deep beams are structural beams with low shear span-to-depth ratio, and hence in which the strain distribution is significantly nonlinear and the conventional beam theory is not applicable. A strut-and-tie model is considered one of the most rational and simplest methods available for shear strength prediction and design of deep beams. The strut-and-tie model approach describes the shear failure of a deep beam using diagonal strut and truss mechanism: The diagonal strut mechanism represents compression stress fields that develop in the concrete web between diagonal cracks of the concrete while the truss mechanism accounts for the contributions of the horizontal and vertical web reinforcements. Based on a database of 406 experimental observations, this paper proposes a new strut-and-tie-model for accurate prediction of shear strength of reinforced concrete deep beams, and further improves the model by correcting the bias and quantifying the scatter using a Bayesian parameter estimation method. Seven existing deterministic models from design codes and the literature are compared with the proposed method. Finally, a limit-state design formula and the corresponding reduction factor are developed for the proposed strut-andtie model.

Evaluation of Ultimate Strength of Reinforced Concrete Deep Beams Using Grid Strut-Tie Model Approach (격자 스트럿-타이 모델 방법을 이용한 철근콘크리트 깊은 보의 극한강도 평가)

  • Kim, Byung-Hun;Lee, Won-Seok;Yun, Young-Mook
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05a
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    • pp.179-182
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    • 2005
  • Recently, many design codes including ACI 318-02 recommend the use of a strut-tie model approach for design of structural concrete with D-region(s). However, there are several unclear problems and shortcomings in the codes' strut-tie model approach. A grid strut-tie model approach was proposed to resolve these problems. In this study, the ultimate strengths of 17 deep beams, the most familiar type of D-regions, were evaluated for the validity check of the grid strut-tie model approach. The analytical results obtained by the approach are compared with those by the strut-tie model approach presented by CEB-FIP, AASHTO LRFD, and ACI 318-02.

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Strength Evaluation of Reinforced Concrete Corbels using Nonlinear Strut-Tie Model Approach (비선형 스트럿-타이 모델 방법에 의한 철근콘크리트 코벨의 강도 평가)

  • 윤영묵;신용목
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.05a
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    • pp.391-396
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    • 2003
  • The concrete corbels consist of various failure mechanisms such as the yielding of the tension reinforcement, the crushing or splitting from compression concrete struts, and localized bearing or shearing failure under the loading plate. However, predicting those failure mechanisms is very difficult. In this study, the ACI 318-02, the softened strut-tie model approach, and the nonlinear strut-tie model approach are applied to ultimate strength analysis of normal strength concrete corbels tested to failure. From the result of the analysis, an effective analysis and design method of normal strength concrete corbels is suggested.

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Indeterminate Strut-Tie Model for Rational Design of Continuous RC Deep Beams (연속지지 RC 깊은 보의 합리적인 설계를 위한부정정 스트럿-타이 모델의 제안)

  • Chae, Hyun-Soo;Kim, Byung-Hun;Yun, Young-Mook
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.265-268
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    • 2006
  • Recently, many design standards recommend the use of a strut-tie model approach for design of structural concrete with D-region(s). However, since the design standards of the conventional strut-tie model approaches are suggested on the assumption of using a determinate strut-tie model, it is difficult to apply an indeterminate strut-tie model in the design of continuous deep beams. In this study, an indeterminate strut-tie model for continuous deep beams is proposed to resolve the problem, and the ultimate strengths of 35 continuous deep beams tested to failure are evaluated for the validity check of the proposed indeterminate strut-tie model. The analytical results by the proposed model are compared with those by the conventional approaches of ACI 318-99 and ACI 318-05.

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Linear and Nonlinear Strut-Tie Model Approaches for Analysis and Design of Structural Concrete (콘크리트 부재의 해석/설계를 위한 선형 및 비선형 스트럿-타이 모델 방법)

  • 윤영묵;김병헌
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.11a
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    • pp.375-379
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    • 2003
  • In this paper, the linear and nonlinear strut-tie model approaches for the analysis and design of concrete structures are suggested. The validity of the approaches are examined through the strength analysis of four dapped-end beams tested to failure. According to the analysis results, the nonlinear strut-tie model approach which takes the various characteristics of nonlinear behaviors into account in the analysis and design of structural concrete and predicts the strength of structural concrete proven to be an effective method for structural analysis and design.

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Determination of strut efficiency factor for concrete deep beams with and without fibre

  • Sandeep, M.S.;Nagarajan, Praveen;Shashikala, A.P.;Habeeb, Shehin A.
    • Advances in Computational Design
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    • v.1 no.3
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    • pp.253-264
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    • 2016
  • Based on the variation of strain along the cross section, any region in a structural member can be classified into two regions namely, Bernoulli's region (B-region) and Disturbed region (D-region). Since the variation of strain along the cross section for a B-region is linear, well-developed theories are available for their analysis and design. On the other hand, the design of D-region is carried out based on thumb rules and past experience due to the presence of nonlinear strain distribution. Strut-and-Tie method is a novel approach that can be used for the analysis and design of both B-region as well as D-region with equal importance. The strut efficiency factor (${\beta}_s$) is needed for the design and analysis of concrete members using Strut and Tie method. In this paper, equations for finding ${\beta}_s$ for bottle shaped struts in concrete deep beams (a D-region) with and without steel fibres are developed. The effects of transverse reinforcement on ${\beta}_s$ are also considered. Numerical studies using commercially available finite element software along with limited amount of experimental studies were used to find ${\beta}_s$.

Ultimate Strength Analysis of Reinforced Concrete Corbels Using Grid Softened Strut-Tie Model (격자 연화 스트럿-타이 모델 방법을 이용한 RC 코벨의 극한강도예측)

  • Yun Young Mook;Kim Byung Hun;Lee Won Seok;Shin Hyo Jung
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.05a
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    • pp.544-547
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    • 2004
  • Predicting the failure modes of reinforced concrete corbels is difficult because the reinforced concrete corbels show the shapes of sudden shear failures at even slight deflection. For this reason, an exact analysis method is demanded highly. In this study, the validity of the grid softened strut-tie model method suggested for concrete member analysis was examined through the ultimate strength evaluation of the reinforced concrete corbels tested to failure. The evaluated ultimate strengths by the grid softened strut-tie model method were compared with those by the ACI 318-02 and the softened strut-tie model method.

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