• KCI Concrete Journal
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• v.14 no.1
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• pp.43-50
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• 2002

In this study, size effect tests were conducted on axial compressive strength of concrete members. An experiment of Mode I failure, which is one of two representative compressive failure modes, was carried out by using dimensionally proportional cylindrical specimens (CS). An adequate notch length was taken from the experimental results obtained from the compressive strength experiment of various initial notch lengths. Utilizing the notch length, specimen sizes were then varied. In addition, new parameters for the modified size effect law (MSEL) were suggested using Levenberg-Marquardt's least square method (LSM). The test results show that size effect was apparent for axial compressive strength of cracked specimens. Namely, the effect of initial notch length on axial compressive strength size effect was apparent.

• Journal of the Korea Concrete Institute
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• v.12 no.6
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• pp.99-108
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• 2000

The size effect on axial compressive strength in notched concrete specimens was experimentally investigated. Based on the concept of the fracture mechanics and size effect law, theoretical studies for axial compressive failure of concrete were reviewed, and two failure modes of concrete specimens under compression were discussed. In this study, experiments of axial compressive failure, which is one of the two failure modes, was carried out by using cylindrical specimens. Adequate notch length was taken from the experimental result of strength variation based on the notch length. And, by taking various sizes of specimens the size effect on axial compressive strength of concrete was investigated. Also, model equations were suggested by modified size effect law (MSEL). The test results show that size effect appears conspicuously for all series of specimens. Additionally, the effect of initial notch length on axial compressive strength was also apparent.

• Computers and Concrete
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• v.26 no.6
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• pp.565-576
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• 2020

Experimental and discrete element methods were used to investigate the effects of angle of Y shape non-persistent joint on the tensile behaviour of joint's bridge area under brazilian test. concrete samples with diameter of 100 mm and thikness of 40 mm were prepared. Within the specimen, two Y shape non-persistent notches were provided. The large notch lengths were 6 cm, 4 cm and 2 cm. the small notch lengths were 3 cm, 2 cm and 1 cm. The angle of larger notch related to horizontal axis was 0°, 30°, 60°, 90°. Totally, 12 different configuration systems were prepared for Y shape non-persistent joints. Also, 18 models with different Y shape non-persistent notch angle and notch length were prepared in numerical model. The large notch lengths were 6 cm, 4 cm and 2 cm. the small notch lengths were 3 cm, 2 cm and 1 cm. The angle of larger notch related to horizontal axis was 0, 30, 60, 90, 120 and 150. Tensile strength of model materil was 1 MPa. The axial load was applied to the model by rate of 0.02 mm/sec. This testing showed that the failure process was mostly governed by the Y shape non-persistent joint angle and joint length. The tensile strengths of the specimens were related to the fracture pattern and failure mechanism of the discontinuities. It was shown that the tensile behaviour of discontinuities is related to the number of the induced tensile cracks which are increased by increasing the joint length and joint angle. The minimum tensile strength occurs when the angle of larger joint related to horizontal axis was 60°. Also, the maximum compressive strength occurs when the angle of larger joint related to horizontal axis was 90°. The tensile strength was decreased by increasing the notch length. The failure pattern and failure strength are similar in both methods i.e. the experimental testing and the numerical simulation methods.