• 한국안전학회지
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• 제24권3호
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• pp.39-46
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• 2009

A recent and promising method for shear strengthening of reinforced concrete(RC) members is the use of near surface mounted(NSM) fiber reinforced polymer(FRP) reinforcement. In the NSM method, the reinforcement is embedded in grooves cut onto the surface of the member to be strengthened and filled with an appropriate binding agent such as epoxy paste or cement grout. This paper illustrates a research program on shear strengthening of RC beams with NSM channel-type FRP beams which is developed in this study. The objective of this study is to clarify the role of channel-type FRP beam embedded to the beam web for shear strengthening of reinforced concrete beams. Included in the study are effectiveness in terms of spacing and angle of channel-type FRP beams, strengthening method, and shear span ratio. the study also aims to understand the additional shear capacity due to glass fiber reinforced polymer beams and carbon reinforced polymer beams. And anther objective is to study the failure modes, shear strengthening effect on ultimate force and load deflection behavior of RC beams embedded with channel-type FRP beams on the shear region of the beams.

• Structural Engineering and Mechanics
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• 제77권4호
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• pp.523-533
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• 2021

The present study investigates the lateral torsional buckling behaviour of pultruded glass fiber reinforced polymer (GFRP) simply supported channel beams subjected to uniform bending about their major axis. A parametric study by varying the sectional geometry and span of channel beams is carried out by using ABAQUS software. The accuracy of the FE models was ensured by verifying them against the available results provided in the literature. The effect of geometric nonlinearity, geometric imperfections, and the dependency of finite element mesh on the lateral torsional buckling were carefully considered in the FE model. Lateral torsional buckling (LTB) strengths obtained from the numerical study were compared with the theoretical LTB strengths obtained based on the Eurocode 3 approach for steel sections. The comparison between the numerical strengths and the design procedure proposed in the literature based on Eurocode 3 approach revealed disagreements. Therefore, a simplified improved design procedure is proposed for the safe design strength prediction of pultruded GFRP channel beams. The proposed equation has been provided that might aid the structural engineers in economically designing the pultruded GFRP channel beams in the future.

• Structural Engineering and Mechanics
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• 제90권2호
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• pp.117-125
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• 2024

This article presents the behaviour and design of cold-formed steel (CFS) web-stiffened lipped channel beams that primarily fail owing to the buckling interaction of distortional and global buckling modes. The incorporation of an intermediate stiffener in the web of the lipped channel improved the buckling performance leads to distortional buckling at intermediate length beams. The prediction of the strength of members that fail in individual buckling modes can be easily determined using the current DSM equations. However, it is difficult to estimate the strength of members undergoing buckling interactions. Special attention is required to predict the strength of the members undergoing strong buckling interactions. In the present study, the geometric dimensions of the web stiffened lipped channel beam sections were chosen such that they have almost equal distortional and global buckling stresses to have strong interactions. A validated numerical model was used to perform a parametric study and obtain design strength data for CFS web-stiffened lipped channel beams. Based on the obtained numerical data, an assessment of the current DSM equations and the equations proposed in the literature (for lipped channel CFS sections) is performed. Suitable modifications were also proposed in this work, which resulted in a higher level of design accuracy to predict the flexural strength of CFS web stiffened lipped channel beams undergoing distortional and global mode interaction. Furthermore, reliability analysis was performed to confirm the reliability of the proposed modification.

• Steel and Composite Structures
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• 제19권2호
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• pp.485-501
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• 2015

Channels are implemented in composite beams as shear connectors in two arrangements, face to face and back to back. No relevant explanation is found in the design codes to clarify the preference of the mentioned arrangements. Besides, the designers do not have a common opinion on this subject; i.e., some recommend the face to face and others, back to back status. In this research, channel shear connectors in composite beams are studied analytically for both arrangements using ABAQUS software. For this purpose, they have been modeled in simply supported beams in the arrangements of face to face and back to back; their effects on the crack initiation load of concrete slabs were monitored. The stiffness values of composite beams were also compared in the two arrangements using force-displacement curve; the results are relatively the same in both cases. Furthermore, the effects of compressive strength of concrete, channel size, length and spacing of channels as well as steel type of channels on the performance of composite beams have been investigated. According to the results obtained in this research, the face to face status shows better performance in comparison with that of back to back, considering the load of concrete fracturing.

• Advances in Computational Design
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• 제1권2호
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• pp.207-220
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• 2016

The aim of this study is to investigate the effect of stiffened element and edge stiffener in the behaviour and flexural strength of built-up cold-formed steel beams. An experimental and analytical analysis of CFS channel sections in four different geometries is conducted, including simple channel sections, a stiffened channel section with or without edge stiffeners. Nonlinear finite element models are developed using finite element analysis software package ANSYS. The FEA results are verified with the experimental results. Further, the finite element model is used for parametric studies by varying the depth, thickness, and the effect of stiffened element, edge stiffener and their interaction with compression flanges on stiffened built-up cold-formed steel beams with upright edge stiffeners. In addition, the flexural strength predicted by the finite element analysis is compared with the design flexural strength calculated by using the North American Iron and Steel Institute Specifications for cold-formed steel structures (AISI: S100-2007) and suitable suggestion is made.

• 한국구조물진단유지관리공학회 논문집
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• 제12권2호
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• pp.171-180
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• 2008

본 논문의 목적은 채널형 단부정착장치를 사용하여 CFRP판으로 보강한 철근콘크리트 보의 구조적 거동을 평가하는 것이다. 총 12개의 시험체를 제작하였으며, 이 중에는 보강판의 효율성을 높이기 위해 채널형 단부정착장치를 사용한 시험체와 사용하지 않은 시험체가 있다. 모든 시험체의 단면 크기는 동일하며, 주철근량과 콘크리트의 강도를 변화시켰다. 하중재하는 모든 시험체에서 4점 휨시험으로 진행되었으며, 각 재료의 변형률, 균열, 하중, 및 파괴모드가 시험 중에 측정되었다. 모든 시험체의 시험결과는 변형, 강도, 그리고 파괴모드 측면으로 분석되었다. 실험결과에 대한 분석를 통해서 채널형 단부정착장치를 사용한 RC보는 그 파괴모드가 급작스런 부착파괴에서 변형이나 강도적 측면에서 구조적 성능이 매우 향상된 연성적 파괴모드로 전환되는 것을 확인할 수 있었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.173-176
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• 2008

본 연구는 다방향 채널형 FRP판으로 보강된 철근콘크리트 보의 전단거동 특성을 규명함에 그 목적이 있다. 본 연구의 목적을 달성하기 위해 실험변수로는 전단 스팬비(a/d), 보강재 종류, 보강 방향, 보강 방법 등을 고려하여 실험을 수행하였다. 보강방법은 전단성능이 취약한 철근콘크리트 보 측면에 홈을 형성하고 에폭시를 충전한 이후 다방향 채널형 FRP판을 삽입하여 부착시켰다. 실험결과 다방향 채널형 FRP판으로 보강된 철근콘크리트 보의 대부분은 보강되지 않은 보에 비해 최대 전단강도가 최대 42%까지 증진 되었다. 또한 다방향 채널형 FRP판은 전단균열의 발생 및 진전을 억제하며, 휨파괴를 유도하는 연성구간의 증진 효과가 매우 좋은 것으로 나타났다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.167-171
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• 2005

The thick open section composite beams are used extensively as load carrying members and stiffeners of structural elements. However, most of studies on thick composite beams are limited only to closed section beams. In this study, an open cross-section thick-walled composite beam model which includes coupled stiffness, transverse shear, and warping effects is suggested and the deflections associated with the thick-walled composite beams and thin-walled composite beams are obtained and compared with the finite element analysis results. The correlation between thin and thick walled composite beam was achieved for two different layup configurations which are the circumferentially asymmetric stiffness (CAS) and circumferentially uniform stiffness (CUS) beams.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권5호
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• pp.2102-2123
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• 2016

This paper considers a channel estimation scheme for millimeter-wave multiuser multiple-input multiple-output systems. According to the proposed method, parts of the beams are selected and the channel parameters are estimated according to the sparsity of channels and the orthogonality of the beams. Since the beams for each channel become distinct and the signal power increases with the increased number of antennas, the proposed approach is able to achieve good estimation performance. As a result, the sum rate can be increased in comparison with traditional approaches, and channels can be estimated with fewer pilot symbols. Numerical results verify that the proposed approach outperforms traditional approaches in cases with large numbers of antennas.

• 설비공학논문집
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• 제7권1호
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• pp.63-72
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• 1995

Convective heat transfer in a two-dimensional horizontal and vertical channel with isothermal rectangular beams attached to one adiabatic wall is investigated from the numerical solution of Navier-Stokes and energy equations. The solutions have been obtained for dimensionless beam spacings, S/L=1~4, aspect ratios of beam, H/B=0.25~4, Reynolds numbers, Re=50~1000 and Grashof numbers, $Gr=0{\sim}5{\times}10^4$. The total mean Nusselt number, Nu_T for horizontal and vertical channels shows same value at Gr=0. As Gr increases, Nu_T for horizontal channel increases, but Nu_T for vertical channel shows similar value at S/L=2, H/B=0.25, Re=100. The total mean Nusselt number for horizontal channel is higher than that for vertical channel. As H/B increases, $Nu_T$ for both channel decrease at $Gr=10^4$, Re=100.