• Title/Summary/Keyword: concrete size effect

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Effect of Aspect Ratio in Direct Tensile Strength of Concrete (콘크리트 직접인장강도의 세장비 효과)

  • Hong, Geon-Ho
    • Journal of the Korea Concrete Institute
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    • v.15 no.2
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    • pp.246-253
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    • 2003
  • Although concrete members are not normally designed to resist direct tension, the knowledge of tensile strength is of value in estimating the cracking load. In general, there are three types of test method for tensile strength ; direct tension test, flexural tension test, and splitting tension test. Though direct tensile strength represents the real tensile strength of concrete, direct tension tests are seldom carried out, mainly because it is very difficult to applicate a pure tension force. The purpose of this paper is to investigate the test methods, effect of aspect ratio, and the size effect on the direct tensile strength. Direct tension test, using bonded end plates, follows RILEM and U.S.Bureau of Reclamation. And other test methods follow ASTM provisions. Four kinds of aspect ratio and two kinds of size effect are tested. Same variables are tested by direct tension test and splitting tension test for comparison between the two test methods. Test results show that direct tensile strength of concrete is more affected by aspect ratio and size than other kinds of strength.

Analytical Study on the Size Effect Influencing Inelastic Behavior of Reinforced Concrete Bridge Piers (철근콘크리트 교각의 비탄성 거동에 미치는 크기효과에 관한 해석적 연구)

  • 김태훈;김운학;신현목
    • Journal of the Earthquake Engineering Society of Korea
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    • v.6 no.1
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    • pp.23-31
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    • 2002
  • The purpose of this study is to investigate the size effect on inelastic behavior of reinforced concrete bridge piers. A computer program, named RCAHEST(reinforced concrete analysis in higher evaluation system technology), for the analysis for 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. 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. To determine the size effect on bridge pier inelastic behavior, a 1/4-scale replicate model was also loaded for comparison with the full-scale bridge pier behavior.

Effect of Maximum Size of Coarse Aggregate on Passing Performance of Concrete between Reinforcing Bars (굵은골재의 최대치수가 콘크리트의 간극통과성에 미치는 영향)

  • Baik Dae-Hyun;Yoon Seob;Kim Jung-Bin;Lee Seong-Yeun;Yoon Ki-Won;Han Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2006.05a
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    • pp.77-80
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    • 2006
  • This study investigated filling performance of concrete which can pass between reinforcing bars and be fully filled, and examined fundamental properties of concrete which is before or after hardened state, in response to maximum size of coarse aggregate. This study was also originally intended to find out one of the method that can improve concrete quality, using crushed coarse aggregate. Test showed that passing ratio of concrete decreased as aggregate site increased and as space between reinforcing bars decreased. In addition concrete using bigger size of coarse aggregate exhibited slightly higher compressive strength and showed lower length change ratio of drying shrinkage.

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The Effect of Fiber Length and Specimen Size on Spalling and Temperature Distribution in High Strength Concrete Specimen (고강도 콘크리트 부재에서 섬유 길이와 부재 크기가 폭렬 특성 및 온도 분포에 미치는 영향)

  • Park, Chan-Kyu;Lee, Seung-Hoon;Sohn, Yu-Shin;Kim, Han-Jun
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05b
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    • pp.17-20
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    • 2006
  • Recently, in order to reduce the spalling of high strength concrete under fire, the addition of organic fibres to high strength concrete has been investigated. In this study, the effect of fiber length and specimen size on the spalling and temperature distribution in high strength concrete specimen was experimentally investigated. Three HSC specimens measuring $305{\times}305mm$, $500{\times}500mm$ and $700{\times}700mm$ with the fiber were prepared. The fiber length was 6mm and 10mm. As a result, it appears that when the remaining ratios(by weight) of fibre at $300^{\circ}C$ and $350^{\circ}C$ are less than 80% and 50%, respectively, the spalling of high strength concrete is prevented.

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Characteristics of Plantable Concrete Using Waste Stone and Stone Dust (폐석과 석분을 사용한 식생 콘크리트의 특성)

  • 성찬용;윤준노
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.44 no.3
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    • pp.85-91
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    • 2002
  • This study is performed to evaluate characteristics of plantable concrete using waste stone and stone dust. The test result shows that the void ratio is decreased as the size of waste stone smaller and the content of stone dust increased. The strength of neutralized plantable concrete is decreased by approximately 4∼5% than that of the normal plantable concrete. The reduction effect of pH value is achieved by chemical treatment. Also, the plant is grown well with increase of the void ratio and size of waste stone.

Effect of Specimen Sizes and Shapes on Compressive Strength of Concrete (콘크리트의 압축강도에 공시체의 크기와 형상이 미치는 영향)

  • Yang Eun-Ik;Choi Joong-Cheol;Yi Seong-Tae
    • Journal of the Korea Concrete Institute
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    • v.16 no.3 s.81
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    • pp.375-382
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    • 2004
  • The compressive strength of concrete is used as the most basic and important material Property when reinforced concrete structures are designed. It has become a problem to use this value, however, because the control specimen sizes and shapes are different from every country. In this study, the effect of specimen sizes and shapes on compressive strength of concrete specimens was experimentally investigated based on fracture mechanics. Experiments for the Mode I failure was carried out by using cylinder, cube, and prism specimens. The test results are curve fitted using least square method(LSM) to obtain the new parameters for the modified size effect law(MSEL). The analysis results show that the effect of specimen sizes and shapes on ultimate strength is apparent. In addition, correlations between compressive strengths with size, shape, and casting direction of the specimen are investigated. For cubes and prisms the effect of placing direction on the compressive strength was investigated.

Fracture energy and tension softening relation for nano-modified concrete

  • Murthy, A. Ramachandra;Ganesh, P.;Kumar, S. Sundar;Iyer, Nagesh R.
    • Structural Engineering and Mechanics
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    • v.54 no.6
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    • pp.1201-1216
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    • 2015
  • This paper presents the details of size independent fracture energy and bi-linear tension softening relation for nano modified high strength concrete. Nano silica in powder form has been used as partial replacement of cement by 2 wt%. Two popular methods, namely, simplified boundary effect method of Karihaloo et al. (2003) and RILEM (1985) fracture energy with P-${\delta}$ tail correction have been employed for estimation of size independent fracture energy for nano modified high strength concrete (compressive strength ranges from 55 MPa to 72 MPa). It is found that both the methods gave nearly same values, which is an additional evidence that either of them can be employed for determination of size independent fracture energy. Bi-linear tension softening relation corresponding to their size independent fracture energy has been constructed in an inverse manner based on the concept of non-linear hinge from the load-crack mouth opening plots of notched three-point bend beams.

Analytical Study on the Strain Localization of Concrete (콘크리트의 변형률국소화에 관한 해석적 연구)

  • Song, Ha-Won;Seo, Chul
    • Magazine of the Korea Concrete Institute
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    • v.8 no.2
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    • pp.129-138
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    • 1996
  • Localization of concrete is a phenomenon such that the deformation of concrete is localized in finite region with softening behavior and it governs ultimate load of concrete. In this Paper, concrete under strain localization was modeled with localization region and non-localization region and lc~calization behavior was formulated based on averaging concept of heterogeneous material. By using the formulation, the localization phenomena of concrete under uniaxial loadings were well predicted. The analytical results show that size of localization region of concrete under uniaxial compression is three times of maximum aggregate size and the size effect of concrete is well predicted. The use of tension-softening curve obtained from direct tension test is suitable for well prediction of localization of concrete under uniaxial tension.

Effect of specimen geometry and specimen preparation on the concrete compressive strength test

  • Aslani, Farhad;Maia, Lino;Santos, José
    • Structural Engineering and Mechanics
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    • v.62 no.1
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    • pp.97-106
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    • 2017
  • This paper discusses an experimental programme that was carried out to study the effects of specimen size-shape and type of moulds on the compressive strength of concrete. For this purpose, cube specimens with 150 mm dimensions, cylinder specimens with $150{\times}300mm$ dimensions, and prism specimens with $150{\times}150{\times}375mm$ dimensions were prepared. The experimental programme was carried out with several concrete compositions belonging to strength classes C20/25, C25/30, C30/37, C40/50 and C60/75. Furthermore, the test results were curve-fitted using the least squares method to obtain the new parameters for the modified size effect law.

On geometry dependent R-curve from size effect law for concrete-like quasibrittle materials

  • Zhao, Yan-Hua;Chang, Jian-Mei;Gao, Hong-Bo
    • Computers and Concrete
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    • v.15 no.4
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    • pp.673-686
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    • 2015
  • R-curve based on the size effect law previously developed for geometrically similar specimens (geometry type III) is extended to geometries with variable depth (geometry type I) as well as with variable notch (geometry type II), where the R-curve is defined as the envelope of the family of critical strain energy release rates from specimens of different sizes. The results show that the extended R-curve for type I tends to be the same for different specimen configurations, while it is greatly dependent on specimen geometry in terms of the initial crack length. Furthermore, the predicted load-deflection responses from the suggested R-curve are found to agree well with the testing results on concrete and rock materials. Besides, maximum loads for type II specimen are predicted well from the extended R-curve.