• 한국구조물진단유지관리공학회 논문집
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• 제25권3호
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• pp.40-47
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• 2021

이 연구는 후크형 강섬유의 체적비 및 형상비에 따른 콘크리트 설계기준강도 30MPa를 갖는 콘크리트의 역학적 특성, 휨 및 압축거동에 미치는 영향에 대하여 분석한다. 실험에서 형상비가 상이한 3종류의 섬유가 사용되었다. 섬유의 형상비는 64, 67, 80이며 섬유의 보강량은 체적비 0.25%, 0.50% 및 0.75%가 선정되었다. 강섬유 보강 콘크리트의 휨거동은 하중-균열폭 곡선, 휨강도 및 휨인성이 평가되었다, 압축거동은 압축응력-변형률 관계 곡선, 압축강도 및 인성 등이 평가되었다. 실험결과로부터 강섬유 보강 콘크리트의 휨강도, 휨인성 및 파괴에너지는 강섬유 혼입량이 증가됨에 따라 향상되는 것으로 나타났다. 그러나 형상 64와 67인 강섬유로 보강된 콘크리트의 역학적 특성은 큰 차이를 보이지 않았다. 이 연구에서 검토된 강섬유 보강 콘크리트의각 배합에 대한 유럽기준(MC2010)에 의한 산정된 휨 잔여강도는 기준에서 인장 철근 또는 보강 매쉬를 대체할 수 있는 한계기준을 모두 충족하는 것으로 나타났다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.98-99
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• 2020

This study is aim to assess mechanical properties which is highly related to structural safe and durability of 100MPa high strength concrete mixed with amorphous metallic fiber. All specimens were heated with low velocity heating rate(1℃/min.), residual compressive strength and residual flexural strength was evaluated. The specimens were cooled down to room temperature after heating. As a result, in the case of 100MPa high-strength concrete, the residual compressive strength enhancing effect of amorphous metallic fiber has showed with the mix proportion of fiber. In addition, residual flexural strength showed more regular pattern before 300℃ then residual compressive strength, but simillar decreasing behavior was shown after 300℃ like residual compressive strength. Further study about fiber pull-out behavior and fiber mechanical, chemical property change due to temperature is needed.

• 한국전산구조공학회논문집
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• 제25권6호
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• pp.541-548
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• 2012

중공슬래브 시스템은 슬래브 두께가 증가해도 자중은 크게 증가하지 않고, 일반슬래브에 비해서 휨성능이 크게 저하되지 않는 장점이 있다. 이러한 경제적인 건물 설계 및 친환경 구조물 구현을 가능하게 하는 시스템에도 불구하고 중공슬래브의 활용도는 현재로서는 낮다고 할 수 있다. 특히 국내의 건축분야에 있어서는 매우 낮은 편이다. 이러한 현 상황의 가장 큰 이유는 중공슬래브의 적용을 위한 구조 해석 및 설계방법이 일반화되어 있지 않다는 것이다. 본 연구에서는 실질적인 압축영역을 고려하기 위해 가정한 중공 단면형상에서 중립축 위치에 따른 압축응력블럭의 체적으로 휨강도 산정식을 제시하였다. 기존 중공부 상부만을 압축영역으로 고려한 휨강도 산정방법은 가장 보수적인 방법으로 판단되며 2개의 대체단면을 설정하여 휨내력을 산정하는 것이 더 실질적인 방법으로 판단된다.

• 한국건설순환자원학회논문집
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• 제7권2호
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• pp.158-165
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• 2019

이 연구의 목적은 알칼리활성 슬래그 기반 섬유보강 복합재료를 보 부재의 재료로 활용하였을 때 휨거동을 해석적으로 분석하는 것이다. 7% 이상의 초고연성이 나타날 수 있는 알칼리활성 슬래그 기반 섬유보강 복합재료를 제조하기 위하여 재료 및 배합을 선정하였고, 재료의 압축강도와 인장성능을 평가하였다. 복합재료는 압축강도 32.7MPa, 인장강도 8.43MPa, 인장변형성능 7.52%를 나타내었다. 초고연성 복합재료로 구성된 보의 휨거동을 분석하기 위하여 4가지 단면에 대하여 비선형 단면 층상화 방법을 사용하여 해석을 수행하였다. 해석결과 초고연성 복합재료로 부분적으로 보강된 경우 8.0%, 콘크리트가 복합재료로 전부 치환되어 전체 보강된 경우 24.7%의 휨강도 증진효과가 있는 것으로 나타났다. 휨강도 증진 효과가 크지 않은 이유는 인장 연단의 변형률이 최대 1.38%로 초고연성 복합재료의 인장변형성능의 18.4%밖에 되지 않기 때문인 것으로 나타났다.

• Computers and Concrete
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• 제11권2호
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• pp.105-121
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• 2013

This paper investigates the parameters that control the design of Fiber Reinforced Polymer (FRP) reinforced concrete flexural members proportioned following the ACI 440.1R-06. It investigates the critical parameters that control the flexural design, such as the deflection limits, crack limits, flexural capacity, concrete compressive strength, beam span and cross section, and bar diameter, at various Mean-Ambient Temperatures (MAT). The results of this research suggest that the deflection and cracking requirements are the two most controlling limits for FRP reinforced concrete flexural members.

• 한국산업융합학회 논문집
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• 제11권1호
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• pp.35-40
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• 2008

Various characters of the concrete are greatly improved as the effect of the steel fiber. As the improvement effect of the steel fiber, the increment in flexural strength, shear strength, toughness, and impact strength are remarkable, and tenacious concrete is obtained. This paper presents model which can predict mechanical behavior of the structure according to aspect ratio and volume fraction of steel fiber. Experiments on compressive strength, elastic modulus and tensile strength were performed with self-made cylindrical specimens of variable aspect ratios. This paper presents an analytical study on the behavior of a beam specimen with steel fiber reinforced concrete(SFRC). The effect of the SFRC on the crack pattern, failure mode and the flexural behavior of the structure were investigated. The analysis model based on the nonlinear layered finite element method was successfully able to find the necessary amount of steel fibers, tensile steels and beam section which can best approximate flexural strength and ductility of a given conventionally reinforced concrete beam.

• Structural Engineering and Mechanics
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• 제59권1호
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• pp.133-151
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• 2016

Self-Compacting Concrete (SCC) has been originally developed in Japan to offset a growing shortage of skilled labors, is a highly workable concrete, which is not needed to any vibration or impact during casting. The utilizing of fibers in SCC improves the mechanical properties and durability of hardened concrete such as impact strength, flexural strength, and vulnerability to cracking. The purpose of this investigation is to determine the effect of steel fibers on mechanical performance of traditionally reinforced Self-Competing Concrete beams. In this study, two mixes Mix 1% and Mix 2% containing 1% and 2% volume friction of superplasticizer are considered. For each type of mixture, four different volume percentages of 60/30 (length/diameter) fibers of 0.0%, 1.0%, 1.5% and 2% were used. The mechanical properties were determined through compressive and flexural tests. According to the experimental test results, an increase in the steel fibers volume fraction in Mix 1% and Mix 2% improves compressive strength slightly but decreases the workability and other rheological properties of SCC. On the other hand, results revealed that flexural strength, energy absorption capacity and toughness are increased by increasing the steel fiber volume fraction. The results clearly show that the use of fibers improves the post-cracking behavior. The average spacing of between cracks decrease by increasing the fiber volume fraction. Furthermore, fibers increase the tensile strength by bridging actions through the cracks. Therefore, steel fibers increase the ductility and energy absorption capacity of RC elements subjected to flexure.

• 산업기술연구
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• 제22권A호
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• pp.177-184
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• 2002

Reinforced concrete(R/C) is commonly used to structures because they have many merits that compressive strength, economy and so on. However, reinforced concrete has a crack at the tensile section which is due to the relatively lower tensile strength than its compressive strength Latex modified concrete(LMC) has higher tensile and flexural strength than the ordinary portland cement, due to the interconnections of hydrated cement and aggregates by a film of latex particles. The purpose of this study was to investigate the flexural behavior of reinforced concrete beam with latex modified concrete, having the main experimental variables such as concrete types(ordinary portland cement concrete, latex modified concrete), latex contents(0%, 15%), flexural steel ratios(0.012, 0.0235), and with/without shear reinforcement. The beam of LMC showed considerably higher initial cracking loads and ductility than that of OPC, but, similar to ultimate strength and deflection. This might be attributed to the interlocking of hydrated cement and aggregates by a film of latex particles, water retention due to hydrophobic, and colloidal properties of the latexes resulting in reduced water evaporation. The beam with latex modified concrete could be adopted at field for controlling and reducing the tensile crack due to its higher tensile strength.

• Computers and Concrete
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• 제32권1호
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• pp.1-13
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• 2023

This paper discusses a framework for predicting the flexural strength of prestressed and non-prestressed FRP reinforced T-shaped concrete beams using soft computing techniques. An analysis of 83 tests performed on T-beams of varying widths has been conducted for this purpose with different widths of compressive face, beam depth, compressive strength of concrete, area of prestressed and non-prestressed FRP bars, elasticity modulus of prestressed and non-prestressed FRP bars, and the ultimate tensile strength of prestressed and non-prestressed FRP bars. By analyzing the data using two soft computing techniques, named artificial neural networks (ANN) and gene expression programming (GEP), the fundamental parameters affecting the flexural performance of prestressed and non-prestressed FRP reinforced T-shaped beams were identified. The results showed that although the proposed ANN model outperformed the GEP model with higher values of R and lower error values, the closed-form equation of the GEP model can provide a simple way to predict the effect of input parameters on flexural strength as the output. The sensitivity analysis results revealed the most influential input parameters in ANN and GEP models are respectively the beam depth and elasticity modulus of FRP bars.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1990년도 가을 학술발표회 논문집
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• pp.63-67
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• 1990

The purpose of this study was to investigate the effects of flexural strength ratio(Mr=$\Sigma$Mc/$\Sigma$Mb) with High-Strength Concrete up to 800Kg/$\textrm{cm}^2$. Five specimens were tested under reversed cyclic loadings. The primary variables were flexural strength ratio of the beam-column, compressive strength of concrete and loading patterns. The results showed that the failure at the beam-column joint in case of high strength concrete was severe more than in case of normal strength concrete when flexural strength ratio 1.4. Thus the part for low limit of flexural strength ratio(Mr=1.4) should be revised for high strengthconcrete.