• Title/Summary/Keyword: biaxial flexural test (BFT)

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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;Zi, Goang-Seup
    • Journal of the Korea Concrete Institute
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    • v.23 no.4
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    • pp.479-486
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    • 2011
  • 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.

An Experimental Study on Strength Properties, Size Effect, and Fatigue Behaviour of Concrete under Biaxial Flexural Stress State (이방향 휨응력상태의 콘크리트 강도 특성, 크기효과 및 피로거동에 관한 실험적 연구)

  • Zi, Goangseup;Kim, Jihwan
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.33 no.3
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    • pp.901-907
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    • 2013
  • In this study, flexural strength properties of concrete under biaxial stress state were experimentally investigated. Tests for size effect and fatigue behaviour of concrete under biaxial stress were carried out by the ASTM C 1550 and the biaxial flexure test(BFT). The results given by the biaxial tests were compared to those by the third-point bending test. Test results showed that biaxial flexural strengths obtained from the ASTM C 1550 and the biaxial flexure test are greater than the strength by the third-point bending test. As the size increases, the uniaxial and biaxial flexural strength decreases. However, the slope of the size effect of the biaxial strength was greater than that of the uniaxial strength. Finally, the fatigue response of concrete under the biaxial stress state was similar with that for uniaxial stress state.

Improved Biaxial Flexure Test (BFT) for Concrete with the Optimum Specimen Geometry (최적 시험체 형상을 고려한 개선된 콘크리트 등방휨인장강도 시험법)

  • Zi, Gooang-Seup;Kim, Ji-Hwan;Oh, Hong-Seob
    • Journal of the Korea Concrete Institute
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    • v.21 no.4
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    • pp.523-530
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    • 2009
  • For designing concrete structures, engineers are provided data from unidirectional flexure test in most cases. But real structural components such as pavements and deck panel are subjected to multiaxial stress throughout their body. Therefore, biaxial flexure test for concrete may be considered as a gage of the performance of concrete in service. In this paper, we propose the optimum biaixial flexture test (BFT) to measure the biaxial flexural strength of concrete. This method are an improved version of the ring-on-ring test which have been used extensively in the fields of ceramics and biomaterials. The optimum geometry of the test specimen was determined by using a three-dimensional finite element analysis. A series of test data obtained from the proposed test method is provided to show that the proposed optimum biaxial flexure test method can be used to identify the biaxial tensile strength of concrete.