• Computers and Concrete
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• 제32권2호
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• pp.173-184
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• 2023

In this study, mechanical, flexural post-cracking, and torsional behaviors of recycled steel fiber-reinforced concrete (RSFRC) incorporating steel fibers obtained from recycling of waste tires were investigated. Initially, three concrete mixes with different fiber contents (0, 40, and 80 kg/m³) were designed and tested in fresh and hardened states. Subsequently, the flexural post-cracking behaviors of RSFRCs were assessed by conducting three-point bending tests on notched beams. It was observed that recycled steel fibers improve the post-cracking flexural behavior in terms of energy absorption, ductility, and residual flexural strength. What's more, torsional behaviors of four RSFRC concrete beams with varying reinforcement configurations were investigated. The results indicated that RSFRCs exhibited an improved post-elastic torsional behaviors, both in terms of the torsional capacity and ductility of the beams. Additionally, numerical analyses were performed to capture the behaviors of RSFRCs in flexure and torsion. At first, inverse analyses were carried out on the results of the three-point bending tests to determine the tensile functions of RSFRC specimens. Additionally, the applicability of the obtained RSFRC tensile functions was verified by comparing the results of the conducted experiments to their numerical counterparts. Finally, it is noteworthy that, despite the scatter (i.e., non-uniqueness) in the aspect ratio of recycled steel fiber (as opposed to industrial steel fiber), their inclusion contributed to the improvement of post-cracking flexural and torsional capacities.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.415-418
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• 2005

Prestressed composite girder bridges with PS tendon at positive flexural moment region offer elastic behavior to higher loads, increased ultimate capacity and reduced structural steel weight. Two beams were tested to examine ultimate behaviors of prestressed composite girder bridges subjected to positive flexural moment. The experimental observations of the Prestressed composite girder bridges subjected to positive flexural moment are investigated and compared to the numerical results obtained by sectional analysis method, and 1-D. and 3-D. finite element analysis methods.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.419-422
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• 2005

Prestressed composite girder bridges with concrete infilled steel tube at negative flexural moment region takes the advantages provided due to the interactive reaction in the steel tube and concrete interface layer, enhancing local buckling resistance and the concrete strength provided by the lateral confining effect of concrete. Two beams were tested to examine ultimate behaviors of prestressed composite girder bridges subjected to negative flexural moment. The experimental observations of the Prestressed composite girder bridges subjected to positive flexural moment are investigated and compared to the numerical results obtained by sectional analysis method, and 1-D. and 3-D. finite element analysis methods.

• 콘크리트학회논문집
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• 제12권6호
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• pp.75-82
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• 2000

Flexural behaviors of two typical architectural precast beam sections ; inverted tee and rectangular - were compared and investigated. The heights of web in inverted tee beams are generally less than half of beam depth in building structures to accomodate the nib of double-tee where the total building height limited considerably. The inverted-tee beams are designed for parking live load - 500kgf/$\m^2$ and market - 1,200kgf/$\m^2$ according to the currently used typical shape in the domestic market building site in Korea. The bottom dimension and area of rectangular beams are same to those of inverted tee beams to compare the flexural behaviors of two beams. These two beams are also reinforced for similar strength. Four flexural tests are performed on two beams. Following results are obtained from the tests; 1) The rectangular beam is simpler in production, transportation, and election, and more economic than the inverted tee beam for these two beams with same dimension and similar strength. 1) The estimations of flexural strength of two beams by Strength Design Method and Strain Compatibility Method is fully complied with the result of tests. However, Strain Compatibility Method is slightly ore accurate than Strength Design Method. 2) Overall deflections of two type beam under the service loads are less than those of the allowable limit in ACI Code provision. 3) The rectangular beam is failed in large deflection (average 12.56mm large) than those of inverted tee beams. 4) The rectangular and inverted tee beams with 6m span develop initial flexural crackings under the 88% of full service loading even though they designed to satisfy the ACI tensile stress limit provisions.

• Structural Engineering and Mechanics
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• 제75권5호
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• pp.595-605
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• 2020

In this study, the flexural behaviors of full-scale prestressed concrete box girders are experimentally investigated. Four girders were fabricated using two types of concrete (compressive strengths: 50 MPa and 70 MPa) and tested under four-point bending until failure. The measured parameters included the deflection, the stress and strain in concrete and steel bars, and cracks in concrete. The measurement results were used to analyze the failure mode, load-bearing capacity, and deformability of each girder. A finite element model is established to simulate the flexural behaviors of the girders. The results show that the use of high-performance concrete and reasonable combination of prestressed tendons could improve the mechanical performance of the box girders, in terms of the crack resistance, load-carrying capacity, stress distribution, and ductility.

• Steel and Composite Structures
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• 제52권3호
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• pp.313-325
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• 2024

This work presents experimental and numerical investigations on the flexural performances of composite deep-deck plate slabs. Seven deep-deck plate slab specimens with topping concrete were fabricated; the height of the topping slab as well as presence and type of shear connector were set as the main variables to perform bending experiments. The flexural behaviors of the specimens and composite behaviors of the deck plate and concrete were analyzed in detail. The contributions of the deck plate to the flexural stiffness and strength of the slab were identified through finite element (FE) analysis. FE analysis was carried out using the validated FE model by considering the varying bond strengths of the deck plates and concrete, thickness of the deck plate, and types and spacings of the shear connectors. Based on the results, the degree of composite of the deep-deck plate was examined, and a flexural strength equation for the composite deck plate slabs was proposed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.190-193
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• 2003

Flexural-torsional behaviors of the typical architectural precast beam sections - inverted tee and rectangular - were compared. The inverted-tee beams were designed with a parking live load - 500kgf/$\textrm{m}^2$ and a market-1,200kgf/$\textrm{m}^2$ according to the currently used typical shape in the domestic market building site. The rectangular beams were also designed as the same bottom dimension and area, and reinforced for similar strength as in the cases of inverted tee beams. Two rectangular and two inverted precast pretensioned concrete beams were tested and analyzed

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.738-741
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• 2004

This study is concerning on modeling to predict the flexural behaviors of FRP-confined concrete structural members. For compressive behaviors of confined concrete by FRP jackets, the hypoelasticity-based constitutive law of concrete has been presented under the basis of three-dimensional stress states. The strength enhancement of concrete wrapped by FRP jackets has been determined by the failure surface of concrete in tri-axial states, and its corresponding peak strain is computed by the strain enhancement factor. The behavior of FRP jackets has been modeled using the mechanics of orthotropic laminated composite materials in two-dimensional stress states. To be based on the three-dimensional constitutive laws, an algorithm for the prediction of flexural bending behaviors of FRP-confined concrete structural member has been presented.

• 대한토목학회논문집
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• 제34권2호
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• pp.447-455
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• 2014

본 연구는 UHPCC (Ultra High Performance Cementitious Composites)에서 섬유배열 유도의 효율성을 평가하기 위한 연구의 일환으로, 흐름특성을 달리한 다양한 방법으로 UHPCC 부재를 제작하여 휨거동의 변화를 비교하고, 섬유 배열특성과의 상관관계를 정성적으로 분석하였다. 실험을 통해 섬유배열 유도방법에 따라 휨거동의 차이가 크게 나타남을 확인하였다. 일반적인 휨실험체 제작방법으로, 섬유가 주인장방향으로 배열되도록 유도한 경우가 다른 방법으로 제작된 휨실험체에 비해 더 높은 휨인장강도와 낮은 변동성을 보였다. 따라서 실제 UHPCC 부재에서의 재료의 휨인장강도는 실험실 수준에서 측정한 휨인장강도와 비교하여 크게 다를 수 있고, 변동성도 더 크게 나타날 수 있음을 반드시 고려해야 할 것이다. 한편, UHPCC의 유동흐름에 따른 섬유의 배열특성의 변화를 흐름의 종류 및 경계면 효과를 고려하여 정성적으로 예측하였으며, 이러한 예측결과는 실험에서 여러 가지 형태로 유도된 유동흐름에 따른 휨인장거동의 변화를 잘 설명하였다.

• Steel and Composite Structures
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• 제22권2호
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• pp.387-398
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• 2016

In order to evaluate the effects of U shape ultra high performance concrete (UHPC) permanent form on the behaviors of Reinforced Concrete (RC) beam, a full scale RC composite beam is designed and tested with U shape UHPC permanent form and a reference RC beam with same parameters is tested simultaneously for comparison. The effects of the permanent form on the failure mode, cracking strength, ultimate capacity and deformation are studied. Test results shows that the contributions of the U shape UHPC permanent form to the flexural cracking behaviors of RC beam are significant. This study may provide a reference for the design of sustainable RC beam with high durable UHPC permanent form.