• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 추계 학술논문 발표대회
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• pp.15-16
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• 2017

In this study, the flexural behavior of fiber-reinforced concrete by fiber type were evaluated. As a result, the flexural strength of the hooked steel fiber-reinforced concrete(HSFRC) was lower than that of the amorphous metallic fiber reinforced concrete(AFRC), however it was shown strain-softening behavior by the pull-out of fiber. The flexural strength and the equivalent flexural strength of polyamide fiber-reinforced concrete(PAFRC) were lower than other specimens, but the equivalent flexural strength ratio was similar to that of AFRC. The flexural behavior of the fiber-reinforced concrete was associated with the bonding and pull-out properties of the fiber and matrix depending on the fiber type.

• Steel and Composite Structures
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• 제45권1호
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• pp.133-145
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• 2022

Steel fiber composite bar (SFCB) is a novel type of reinforcement, which has good ductility and durability performance. Due to the unique pseudo strain hardening tensile behavior of SFCB, different flexural behavior is expected of SFCB reinforced concrete (SFCB-RC) beams from traditional steel bar reinforced concrete (S-RC) beams and FRP bar reinforced concrete (F-RC) beams. To investigate the flexural behavior of SFCB-RC beam, four points bending tests were carried out and different flexural behaviors between S/F/SFCB-RC beams were discussed. An flexural analytical model of SFCB-RC beams is proposed and proved by the current and existing experimental results. Based on the proposed model, the influence of the fiber volume ratio R of the SFCB on the flexural behavior of SFCB-RC beams is discussed. The results show that the proposed model is effective for all S/F/SFCB-RC flexural members. Fiber volume ratio R is a key parameter affecting the flexural behavior of SFCB-RC. By controlling the fiber volume ratio of SFCB reinforcements, the flexural behavior of the SFCB-RC flexural members such as bearing capacity, bending stiffness, ductility and repairability of SFCB-RC structures can be designed.

• Computers and Concrete
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• 제10권3호
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• pp.241-258
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• 2012

The need for long-span members increases gradually in recent years, which makes issues not only on ultimate strength but also on excessive deflection of horizontal members important. In building structures, the post-tension methods with unbonded tendons are often used for long-span members to solve deflection problems. Previous studies on prestressed flexural members with unbonded tendons, however, were mostly focused on the ultimate strength. For this reason, their approaches are either impossible or very difficult to be implemented for serviceability check such as deflection, tendons stress, etc. Therefore, this study proposed a flexural behavior model for post-tensioned members with unbonded tendons that can predict the initial behavior, before and after cracking, service load behavior and ultimate strength. The applicability and accuracy of the proposed model were also verified by comparing with various types of test results including internally and externally post-tensioned members, a wide range of reinforcement ratios and different loading patterns. The comparison showed that the proposed model very accurately estimated both the flexural behavior and strength for these members. Particularly, the proposed model well reflected the effect of various loading patterns, and also provided good estimation on the flexural behavior of excessively reinforced members that could often occur during reinforcing work.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.475-480
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• 2003

Latex modification of concrete provides the material with higher flexural strength. This increase in flexural strength can attribute to the crack-arresting action of polymer in concrete, and also to the bonding they provide between the matrix and aggregates. This experimental study presents the fracture behavior of 12 flexural reinforced concrete beams repaired or strengthened by latex-modified concrete with the main experimental variables such as overlay thickness, strength thickness, and shear reinforcement. The results are as follow: All beam specimens having shear reinforcement were failed by delamination rupture at concrete interface at about 80% of ultimate loading after flexural cracking. All specimens overlayed and strengthened by latex-modified concrete (LMC) showed higher ultimate flexural strength than OPC control specimen, but lower than LMC control specimen. This increase in flexural strength could attribute to the high bonding they provide between the matrix and aggregates. All specimens except two shear unreinforced showed quite similar and consistent displacement behavior. The effect of overlay and strength thickness on the load-displacement relationship were a small at this study.

• 전산구조공학
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• 제3권4호
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• pp.113-122
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• 1990

SFRC보의 휨 거동에 대한 이론적인 해석이 제시되었다. Critical region내의 곡률변화와 균열 양상이 고려되었으며 이를 위해 SFRC의 압축응력-변형도와 특히 SFRC의 인장 최대하중 후 응력-균열 열림관계(stress-crack opening relationship)로 표현된 인장 constitutive모델이 비선형 휨 해석에 이용되었다. 제시된 모델의 해석치는 실험치와 비교할 때 만족스러웠으며 이 모델을 이용, SFRC보의 휨 거동에 미치는 여러 영향들과 위험 단면(critical section)의 거동이 고찰되었다. 또한 단순 관찰과 통계적인 접근을 통해 SFRC보의 휨 거동에 큰 영향을 미치는 변수(parameters)들을 찾아내었다.

• 한국구조물진단유지관리공학회 논문집
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• 제22권2호
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• pp.26-33
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• 2018

본 논문은 SIFCON으로 제작된 휨부재의 휨거동에 대한 실험적 해석적 연구결과를 제시한다. 우선, 12개의 SIFCON 보에 대한 휨 실험을 실시하고 휨거동을 평가하였다. 실험변수로는 강섬유 종류, 인장철근 유 무, 단면의 높이를 고려하였다. Type-A 강섬유보다 뽐힘저항성이 우수한 Type-B 강섬유를 사용한 시험체는 전단파괴가 발생하지 않고 휨파괴 거동을 보였으며, 강섬유 형상비는 인장철근을 사용하지 않는 SIFCON 보의 거동에 큰 영향을 주었으나 인장철근을 갖는 SIFCON 보의 거동에 대해서는 그 영향이 매우 미미하게 나타났다. 추가적으로 본연구에서는 SIFCON에 대한 휨강도 예측식을 제시하였다. 휨강도 예측값에 대한 실험값의 비의 평균과 표준편차가 각각 1.02와 0.04로 나타나 휨강도 예측식은 SIFCON 보의 설계 및 성능 평가에 유용하게 사용될 수 있을 것으로 생각된다.

• Computers and Concrete
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• 제30권3호
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• pp.165-173
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• 2022

The effect of basalt and polypropylene fibers on the flexural behavior of reinforced concrete (RC) beams is investigated in this paper. The compressive and tensile behaviors of the basalt concrete and polypropylene concrete cylinders are also investigated. Eight beams and 28 cylinders were made with different percentages of basalt and polypropylene fibers. The dosages of fiber were selected as 0.6%, 1.3%, and 2.5% of the total cement weight. Each type of fiber was mixed solely with the concrete mix. Basalt and polypropylene fibers are modern and cheap materials that can be used to improve the structural behavior of RC members. This research is designed to find the optimum percentage of basalt and polypropylene fibers for enhancing the flexural behavior of RC beams. Test results showed that the addition of basalt and polypropylene fibers in any dosage (0.6%, 1.3%, and 2.5%) can increase the flexural strength and displacement ductility index of the beams where the maximum enhancement was measured with 1.3% fibers. The maximum increments in the flexural strength and the displacement ductility index were 30.39% and 260% for the basalt fiber case, while the maximum improvement for the polypropylene fibers case was 55.5% and 230% compared to the control specimen. Finite element (FE) models were then developed in ABAQUS to predict the numerical behaviour of the tested beams. The FE models were able to predict the experimental behaviour with reasonable accuracy. This research confirms the efficiency of basalt and polypropylene fibers in enhancing the flexural behavior of RC beams, and it also suggests the optimum dosage of fibers.

• 한국공간구조학회논문집
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• 제14권2호
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• pp.79-86
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• 2014

The purpose of this study is intended to determine the validity of shear reinforcement by evaluating flexural performance in the hollow slab. The hollow slab is relatively light and second moment of inertia is large. Due to these characteristics, it can be used to slab system efficiently. Therefore the prediction of the structural behaviors is very important because of decrease of shear and flexural strength which is caused by hollow section of slab interior. In this study, the flexural test were performed to analyze the flexural capacity of the hollow slab w/ or w/o shear reinforcement. A total of six full scale specimens were tested. These specimens have three cases of reinforcing bar ratio, 0.009, 0.018 and 0.024. To verify the flexural behavior such as ultimate load, load-deflection and crack pattern, the flexural experiment were tested by using loading frame. Experimental results have shown that the flexural behavior are depend on the reinforcing bar ratio. Also the hollow slab with shear reinforcement have shown flexural behavior. Therefore, it is appropriate that the hollow slab is reinforced by shear reinforcement to improve the flexural performance of the hollow slab.

• 한국구조물진단유지관리공학회 논문집
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• 제4권3호
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• pp.197-204
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• 2000

Tensile strength (stress) of bar splice is important in the research of mechanical behavior of reinforced concrete structures-beam, column etc.- with bar splice. The purpose of this research is to evaluate the flexural behavior - deflection of beam specimens, strain of main bars - of reinforced concrete beam with Lock Joint Coupler. To make a comparative research, reinforced concrete beam specimens with normal deformed bar and lap splice are tested and analyzed. Test results, Comparing a deflection of three types flexural specimens, a flexural specimen with Lock Joint Coupler is 40% greater than the other flexural specimens. At the center of flexural specimen, the strain of main bar(D29) with lock joint coupler is 50% less, and vice versa, at the point of 14cm far from the center of flexural specimen, the strain of main bar(D29) with lock joint coupler is 9% larger than the strain of main bar(D29) which calculated using the classical flexure theory. A discords, between a deflection behavior of the flexural specimens and a strain of the main bar, are caused by the difference of strain between the lock joint coupler and main bar, near the lock joint coupler. So, additional research is need to verify as stated above discords.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 춘계학술발표대회 논문집
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• pp.147-151
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• 2003

In this study, we discussed the local buckling behavior of pultruded structural flexural members. Previous works were briefly reviewed and the local buckling behavior of orthotropic box-shape flexural members was discussed. The simplified form of equation for finding the width ratio of plate element of box-shape flexural members in which all plate components buckle simultaneously was proposed and the macro flow-chart for finding local buckling strength of pultruded flexural members was also suggested. To establish the design guide line for the local buckling of pultruded flexural members, further studies need to be performed as follows; the simplified form of solutions for finding the minimum buckling coefficient of orthotropic plate with various loading and boundary conditions including rotationally restrained boundary conditions, the simplified form of equation for calculating the coefficient of restraint provided by the adjacent plate elements.