• 한국공간구조학회논문집
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• 제17권4호
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• pp.159-165
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• 2017

In this paper, uniaxial tensile tests of ETFE films with three kinds of thicknesses(100, 200, $250{\mu}m$) and two kinds of directions(machine direction & transverse direction) are performed and the tensile strength, the tensile strain at break and the Young's modulus of ETFE films are compared for two kinds of specimen types(2 & 5). It could be figured out that there are no significant difference between tensile strengths of two specimen types but the tensile strain at break and the Young's modulus of ETFE films are affected by the specimen types. And it is concluded that the uniaxial tensile test of specimen type 2 are more reliable than that of specimen type 5.

• 대한토목학회논문집
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• 제30권2A호
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• pp.185-191
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• 2010

콘크리트 구조물의 사용성과 내구성 저하의 원인이 되는 균열은 응력의 크기, 응력구배 및 기타 구조적 재료적 원인 등에 의하여 발생하기 때문에 콘크리트의 균열강도를 정확히 예측하기는 매우 어렵다. 특히 판구조의 경우 기존의 일축휨강도에 의한 균열평가가 실제 구조물의 균열강도와 상이할 수 있다. 본 연구에서는 이축휨인장강도 평가에 적합한 시험체 제원을 적용하여 일축과 이축휨강도 특성을 비교, 평가하였다. 실험결과 골재의 크기 및 실험체 크기의 증가에 따라 일축 및 이축휨강도 모두 강도가 저하되는 것으로 나타났다. 일축휨강도에 비하여 이축휨강도가 일축휨강도의 39.5~99.2%로서 전반적으로 낮은 강도를 갖는 것으로 평가되었으며, 특히 20 mm 골재를 사용한 경우에는 76%정도로 고찰되었다.

• 한국구조물진단유지관리공학회 논문집
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• 제6권1호
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• pp.223-231
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• 2002

The pilot tests for the development of biaxial failure envelope of high strength concrete of reactor containments were performed. To apply biaxial loads to concrete, the plate specimens were used. The technical difficulties encountered on the development of a suitable biaxial test setup were discussed. To decide the optimum thickness of plate specimen, the nonlinear finite element analyses using ABAQUS were performed for a 1/8 model of cylindrical specimen(${\Phi}150{\times}300$) and four 1/4 models of plate Specimens ($200{\times}200{\times}T$(=30, 50, 60, 70)mm) under uniaxial compression. Analytical values and test data of relative strength ratio between those specimens with different geometric shapes were also compared. The various test data were obtained under uniaxial compression, uniaxial tension, and biaxial compression and then the stress-strain responses were plotted. The test data indicated that the strength of concrete under biaxial compression, $f_1/f_2=-1/-1$, is 15 percent larger than that under uniaxial compression and the poisson's ratio of concrete is 0.16. Teflon pads employed to eliminate friction between test specimen and loading platens showed an excellent effect under biaxial compression.

• Advances in Computational Design
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• 제7권4호
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• pp.281-295
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• 2022

Tensile property is one of the excellent properties of ultra-high performance concrete (UHPC), and uniaxial tensile test is an important and challenging mechanical performance test of UHPC. Traditional uniaxial tensile tests of concrete materials have inherent defects such as initial eccentricity, which often lead to cracks and failure in non-test zone, and affect the testing accuracy of tensile properties of materials. In this paper, an original integrated design scheme of mould and end fixture is proposed, which achieves seamless matching between the tension end of specimen and the test fixture, and minimizes the cumulative eccentricity caused by the difference in the matching between the tension end of specimen and the local stress concentration at the end. The stress analysis and optimization design are carried out by finite element method. The curve transition in the end of specimen is preferred compared to straight line transition. The rationality of the new integrated design is verified by uniaxial tensile test of strain hardening UHPC, in which the whole stress-strain curve was measured, including the elastic behavior before cracking,strain hardening behavior after cracking and strain softening behavior.

• Steel and Composite Structures
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• 제15권6호
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• pp.659-677
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• 2013

This paper introduces new specimens of Steel-Carbon Fibre Reinforced Polymer composite developed in accordance with standard test method and definition for mechanical testing of steel (ASTM-A370). The main purpose of this research is to study the behaviour of steel-CFRP composite specimen under uniaxial tension to use it in beams in lieu of traditional steel bar reinforcement. Eighteen specimens were prepared and divided into six groups, depending upon the number of the layers of CFRP. Uniaxial tensile tests were conducted to determine yield strength and ultimate strength of specimens. Test results showed that the stress-strain curve of the composite specimen was bilinear prior to the fracture of CFRP laminate. The tested composite specimens displayed a large difference in strength with remarkable ductility. The ultimate load for Steel-Carbon Fibre Reinforced Polymer composite specimens was found using the model proposed by Wu et al. (2010) and nonlinear FE analysis. The ultimate loads obtained from FE analysis are found to be in good agreement with experimental ones. However, ultimate loads obtained applying Wu model are significantly different from experimental/FE ones. This suggested modification of Wu model. Modified Wu's model which gives a better estimate for the ultimate load of Steel-Carbon Fibre Reinforced Polymer (SCFRP) composite specimen is presented in this paper.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.873-878
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• 2000

Tension stiffening effects of reinforced concrete member with large diameter bar, mainly used at reactor building of nuclear power plant, are studied by uniaxial structural tests. Bond length and stress of steel bar, size of steel bar, and compressive strength of concrete are evaluated to tension stiffening by uniaxial tests. Problems and solution during the uniaxial test are suggested. The prevent splitting cracks, concrete cover-to-bar diameter ratio $c/d_{b}$ is kept 2.6~2.8. Because the bond length is increased as the size of steel bar, the specimen length of the D35 steel bar is required at least 2.0 m. The specimen length must be decided with bond length as well as concrete cover-to-bar diameter ratio to prevent splitting crack.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 추계 학술논문 발표대회
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• pp.28-29
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• 2016

By Testing restrained shrinkage, it is possible to estimating the cracking tendency of concrete such as time to cracking, tensile stress and tensile creep. In this study, tensile creep properties of concrete under restraint shrinkage were investigation through comparison of specimens that JIS and AASHTO proposed. As a results, tensile creep strains in concrete ring specimens were 15% higher than those in uniaxial specimens.

• Geomechanics and Engineering
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• 제14권3호
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• pp.225-231
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• 2018

In this paper, in order to explain the splitting of cylindrical rock specimen under uniaxial loading, cracks in cylindrical rock specimen are divided into two kinds, the longitudinal crack and the slanting crack. Mechanical behavior of the rock is described by elastic-brittle-plastic model and splitting is assumed to suddenly occur when the uniaxial compressive strength is reached. Expression of the stresses induced by the longitudinal crack in direction perpendicular to the major axis of the crack is deduced by using the Maxwell model. Results show that the induced stress is tensile and can be greater than the tensile strength even before the uniaxial compressive strength is reached. By using the Inglis's formula and simplifying the cracks as slender ellipse, the above conclusions that drawn by using the Maxwell model are confirmed. Compared to shearing fracture, energy consumption of splitting seems to be less, and splitting is most likely to occur when the uniaxial loading is great and quick. Besides, explaining the rock core disking occurred under the fast axial unloading by using the Maxwell model may be helpful for understanding that rock core disking is fundamentally a tensile failure phenomenon.

• Advanced Composite Materials
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• 제18권4호
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• pp.395-413
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• 2009

Impact tests on high-strength membrane materials under biaxial loads were experimentally conducted in order to evaluate influence of biaxial loads on impact fracture of the membrane materials for the inflated applications. Cruciform specimens of the membrane materials were fabricated for applying biaxial loadings during the impact test. A steel ball was shot using a compressed nitrogen gas gun, and struck the membrane specimen. Impact tests on uniaxial strip specimens were also conducted to obtain the effect of specimen configuration and boundary condition on the impact fracture. The results of the measured crack length and the ultra-high speed photographs indicate the impact fracture properties of the membrane fabrics under biaxial loadings. Crack length due to the impact increased with applied tensile load, and the impact damages of the cruciform membrane materials under biaxial loadings were smaller than those of under uniaxial loadings. Impact fracture of the strip specimen was more severe than that of the cruciform specimen due to the difference of boundary conditions.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2007년도 추계학술발표논문집
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• pp.325-330
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• 2007

Uniaxial tensile test are generally much simpler than uniaxial compressive test. Uniaxial compressive test is experimentally more difficult because of the low buckling resistance of a sheet of paper. In order to avoid buckling, many researchers have applied various lateral restraint techniques to investigate paper uniaxial compression behavior. Adding unnecessary force to inhibit compressive deformation of the sheet is unwanted, but sufficient force must be used to inhibit buckling. This study has been carried out to develop new uniaxial compressive standard test method without exerting unnecessary force to paper specimen to prevent buckling.