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http://dx.doi.org/10.4334/JKCI.2002.14.6.934

Size Effect on Flexural Compressive Strength of Reinforced Concrete Beams  

김민수 (한국과학기술원 건설 및 환경공학과)
김진근 (한국과학기술원 건설 및 환경공학과)
이성태 (한국전력기술(주))
김장호 (세종대학교 토목환경공학과)
Publication Information
Journal of the Korea Concrete Institute / v.14, no.6, 2002 , pp. 934-941 More about this Journal
Abstract
It is important to consider the effect of member size when estimating the ultimate strength of a concrete flexural member because the strength always decreases with an increase of member size. In this study, the size effect of a reinforced concrete (RC) beam was experimentally investigated. For this purpose, a series of beam specimens subjected to four-point loading were tested. More specifically, three different effective depth (d$\approx$15, 30, and 60 cm) reinforced concrete beams were tested to investigate the size effect. The shear-span to depth ratio (a/d=3) and thickness (20 cm) of the specimens were kept constant where the size effect in out-of-plane direction is not considered. The test results are curve fitted using least square method (LSM) to obtain parameters for the modified size effect law (MSEL). The analysis results show that the flexural compressive strength and the ultimate strain decrease as the specimen size increases. In the future study, since $\beta_1$ value suggested by design code and ultimate strain change with specimen size variation, a more detailed analysis should be performed. Finally, parameters for MSEL are also suggested.
Keywords
size effect; flexural member; flexural compressive strength; stress-strain relationship; modified size effect law (MSEL);
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  • Reference
1 Hubert, R., "Research towards a General Flexural Theory for Structural Concrete," ACI Journal, Proceedings, Vol. 57, No.1, July 1960, pp.1-28.
2 Kim, J. K and Eo, S. H., Park, H. K, "Size Effect in Concrete Structures without Initial Crack," Fracture Mechanics : Application to Concrete, SP-118, ACI, Detroit, 1989, pp.179-196.
3 Yi, S. T., Kim, J. H. J., and Kim, J. K., "Effect of Specimen Sizes on ACI Rectangular Stress Block for Concrete Flexural Members," ACI Structural Journal, Vol. 99, No. 5, Sep.-Oct. 2002, pp.701-708
4 Benjamin, J. R. and Cornell, C. A, "Probability, Statistics, and Decision for Civil Engineers," McGraw-Hill, New York, 1970, Section 4.3.
5 한국콘크리트학회, "콘크리트구조설계기준", 1999. pp.222.
6 Hillerborg, A., "Fracture Mechanics Concepts Applied to Moment Capacity and Rotational Capacity of Reinforced Beams," Proc. Int. Conf. Fracture and Damage Mechanics of Concrete and Rock, Vienna, 1988, pp.233-240.
7 IMSL, Library, Edition 8, IMSL, Inc., Sixth Floor, NBC Building, 7500 Bellaire Blvd., Houston, Texas 77036.
8 Bazant, Z. P., "Size Effect in Blunt Fracture : Concrete, Rock Metal, " Journal of Engineering Mechanics, ASCE, Vol. 110, No. 4. Apr. 1984, pp.518-535.   DOI   ScienceOn
9 Nilson, A. H. and Slate, F. O., "Structural Properties of Very High Strength Concrete," Second Progress Report, Department of Structural Engineering, Cornell University, Ithaca, 1979, pp.62
10 Kim, J. K. and Eo, S. H., "Size Effect in Concrete Specimens with Dissimilar Initial Cracks," Magazine Concrete Research, Vol. 42, No. 153, 1990, pp.233-238.   DOI
11 Kim, J. K., Yi, S. T., and Yang, E. I., "Size Effect on Flexural Compressive Strength of Concrete Specimens," ACI Structural Journal, Vol. 97, No.2, Mar.-Apr. 2000, pp.291-296.
12 Kim, J. K., Yi, S. T., and Kim, J. H. J., "Effect of Specimen Sizes on Flexural Compressive Strength of Concrete," ACI Structural Journal, Vol. 98, No. 3, May-Jun. 2001, pp.416-424.
13 Hognestad, E. Hanson, N. W., and McHenry, D., "Concrete Stress Distribution in Ultimate Strength Design," Journal of ACI, Proceedings, Vol. 27, No. 4, Dec. 1955, pp.455-479.
14 Bazant, Z. P., "Identification of Strain-Softening Constitutive Relation from Uniaxial Tests by Series Coupling Model for Localization," Cement and Concrete Research, Vol. 19, 1989, pp.973-977.   DOI   ScienceOn