Journal of the Korea Concrete Institute (콘크리트학회논문집)

Korea Concrete Institute (한국콘크리트학회)
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An Experimental Study on the Flexural Behavior of the Round Concrete Panels according to the Evaluation Method of Biaxial Flexural Tensile Strengths

휨인장강도 평가 방법에 따른 콘크리트 원형패널의 휨거동에 관한 실험적 연구

  • Kim, Ji-Hwan (School of Civil, Environmental and Architectural Engineering, Korea University) ;
  • Zi, Goang-Seup (School of Civil, Environmental and Architectural Engineering, Korea University)
  • 김지환 (고려대학교 건축사회환경공학과) ;
  • 지광습 (고려대학교 건축사회환경공학과)
  • Received : 2011.02.22
  • Accepted : 2011.07.05
  • Published : 2011.08.31
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Abstract

In this study, we conducted experiment and finite element analysis on the flexural behavior of the round concrete panels according to the evaluation method of biaxial flexural tensile strengths. The Round Panel Test (RPT) and the Biaxial Flexure Test (BFT) were used to determine the biaxial flexural strength of round plain concrete panels. In order to understand the stress distribution on the panels, we measured load-strain relationship at the center of the panels' bottom surface. Test results show that fracture pattern in RPT and BFT panels are similar, and the tensile stress distribution is uniform in all directions at the center of the bottom surface of the panels for both RPT and BFT. The distribution of stresses in two test specimens coincided with the analysis result. The average biaxial flexural strength of RPT is about 29% greater than those of the BFT. The coefficient of variations (COV) of the RPT and BFT for the biaxial flexure strength is 8%, 6%, respectively, which indicates that BFT method is useful and reliable for determining biaxial flexural strengths of the concrete.

이 연구에서는 휨인장강도 평가 방법에 따른 무근 콘크리트 원형패널의 휨거동을 비교하기 위해 유한요소해석과 실험을 수행하였다. 이를 위해 ASTM C 1550 round panel test(RPT) 시험법과 biaxial flexure test(BFT) 시험법을 적용하여 콘크리트 원형패널의 휨인장강도를 측정하였으며, 두 원형패널에 작용하는 응력 분포를 알아보기 위하여 패널의 아랫면 중앙에 두 개의 변형률 게이지가 직교하도록 부착하여 하중-변형률 관계를 측정하였다. 실험 결과 RPT 시험체와 BFT 시험체의 파괴 형상은 유사하게 관찰되었으며, 두 시험체 모두 중앙 아랫면의 하중-변형률 관계 또한 모든 방향에 일정한 것으로 나타나, 시험 시 등방성 휨인장응력 상태에 놓이는 것을 확인할 수 있었다. RPT 시험에 의한 평균 휨인장강도가 BFT의 경우보다 29% 더 큰 것으로 나타났다. 두 시험체의 휨인장강도 분포 모두 정규분포를 보이는 것으로 나타났으며, RPT 휨인장강도의 변동계수(coefficient of variation)와 BFT의 변동계수는 각각 8%와 6%로 측정되었다. 이는 BFT 시험을 통하여 신뢰할 수 있는 이방향 휨인장강도 측정이 가능한 것으로 판단된다.

Keywords

References

  1. Ali, F., "Is High Strength Concrete More Susceptible to Explosive Spalling than Normal Strength Concrete in Fire?," Fire and Materials, Vol. 26, 2002, pp. 127-130. https://doi.org/10.1002/fam.791
  2. Mehta, P. K. and Monteiro, P. J. M. Concrete Microstructure, Properties, and Materials 3th Edition, The McGraw Hill, New York, 2006, pp. 72-75.
  3. Ban, S. and Anusavice, K. J. "Influence of Test Method on Failure Stress of Brittle Dental Materials," J. Dent Res 69, 1990, pp. 1791-1799. https://doi.org/10.1177/00220345900690120201
  4. Ritter, J. E., Jakus, K., Batakis, A., and Bandyopadhyay N., "Appraisal of Biaxial Strength Testing," J. Non-Cryst Solids, 38-39, 1980, pp. 419-424. https://doi.org/10.1016/0022-3093(80)90455-X
  5. ASTM C 1550, Standard Test Method for Flexural Toughness of Fiber-Reinforced Concrete (Using Centrally-Loaded Round Panel), ASTM, West Conshohocken, PA, 2002.
  6. 지광습, 오홍섭, 최진혁, "콘크리트의 순수 등방성 휨인장강도 시험법," 대한토목학회 논문집, 27권, 5A호, 2007, pp. 753-758.
  7. Zi, G., Oh, H., Park, and S. K., "Novel Indirect Tensile Test Method to Measure the Biaxial Tensile Strength of Concretes and Other Quasibrittle Materials," Cement and Concrete Research, Vol. 38, No. 6, 2008, pp. 751-756. https://doi.org/10.1016/j.cemconres.2008.02.002
  8. RTA (Roads and Traffic Authority of NSW) Specification T373, Round Determinate Panel Test, B-82, Shotcrete Work, 2000.
  9. ASTM F 394-78 (Reapproved 1996), Standard Test Method for Biaxial Flexure Strength (Modulus of Rupture) of Ceramic Substrates, American Society For Testing And Materials, 1996.
  10. Marshall, D. B., An Improved Biaxial Flexure Test for Ceramics, American Ceramics Society, Bulletin 59, 1980, pp. 551-553.
  11. Fessler, H. and Fricker, D. C., "A Theoretical Analysis of the Ring-on-Ring Loading Disk Test," J. Am. Ceram. Soc., Vol. 67, 1984, pp. 582-588(correction: 1988, 71(10), 904). https://doi.org/10.1111/j.1151-2916.1984.tb19598.x
  12. Willshaw, T. R., "Measurement of Tensile Strength of Ceramics," J. Am Ceram Soc., Vol. 51, No. 2, 1968, 111 pp. https://doi.org/10.1111/j.1151-2916.1968.tb11849.x
  13. Weibull, W., "A Statistical Theory of the Strength of Materials," Ingvetensk Akad. Handl. 151, 1939, pp. 1-45.
  14. Baant, Z. P. and Planas, J., "Fracture and Size Effect in Concrete and Other Quasibrittle Materials," CRC Press, Boca Raton and London, 1997, pp. 437-486.
  15. Baant, Z. P., "Probabilistic Modeling of Quasibrittle Fracture and Size Effect," Proc., 8th Int. Conf. on Structural Safety and Reliability (ICOSSAR), Newport Beach, Calif., R. B. Corotis, G. I. Schueller, and M. Shinozuka, eds., Swets and Zeitinger, Balkema, 2001, pp. 1-23.
  16. Baant, Z. P., "Probability Distribution of Energetic-Statistical Size Effect in Quasibrittle Fracture," Probab. Eng. Mech., Vol. 19, No. 4, 2004, pp. 307-319. https://doi.org/10.1016/j.probengmech.2003.09.003
  17. Wright, P. J. F., "The Effect of the Method of Test on the Flexural Strength of Concrete," Magazine of Concrete Research, 11, 1952, pp. 67-76.
  18. Neville, A. M., Properties of Concrete, In: (3rd Ed. ed.), Pitman Pub. Ltd., London, 1991, pp. 174-175.
  19. 지광습, 김지환, 오홍섭, "최적 시험체 형상을 고려한 개선된 콘크리트 등방휨인장강도 시험법," 콘크리트학회논문집, 21권, 4호, 2009, pp. 523-530. https://doi.org/10.4334/JKCI.2009.21.4.523
  20. 한국산업규격, 콘크리트의 압축 강도 시험 방법, KS F 2405, 기술표준원, 1964.
  21. 한국산업규격, 콘크리트의 강도 시험용 공시체 제작방법, KS F 2403, 기술표준원, 2005.
  22. Vitman, F. F. and Pukh, V. P., "A Method for Determining the Strength of Sheet Glass," Zavodskaya Laboratoriya, Vol. 29, 1963, pp. 863-867.
  23. Timoshenko, S. P. and Woinowsky-Krieger, S., Theory of Plates and Shells, 2nd Edition, McGraw-Hill, New York, 1959, pp. 63-67.
  24. Westergaard, H. M., "New Formulas for Stresses in Concrete Pavements of Airfields," ASCE Proceedings, 1947, pp. 425-439.
  25. Westergaard, H. M., "Analytical Tools for Judging Results of Structural Tests of Concrete Pavements," Public Roads, Vol. 14, No. l0, 1933, pp. 185-88.
  26. Westergaard, H. M., "Stresses in Concrete Pavements Computed by Theoretical Analysis," Public Roads, 7, 1926, pp. 25-35.