• 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.

• 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.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.709-714
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• 1997

Recently, the repair materials for defected RC structures are being developed and the performance on repaired RC structures are being studied. This experiment is aimed to evaluate the flexural performance of the RC beams repaired by premix-type materials. The parameters used in this study is the repair materials, the repair length and the treatment of interface. Flexural capacity of repaired RC beams except the polymer-repaired RC beams are similar to that of the control beam. In the flexural capacity, the RC beams treated with chipping show better results than the RC beam without chipping. The various repair lengths of the repaired RC beam are not affected to the flexural capacity.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.161-164
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• 2005

The flexural behavior of a strengthened beam, that is a reinforced. concrete beam with externally bonded fiber sheets, was theoretically and experimentally investigated. The effects of the amount of glass fiber sheets varying from 1 to 4 plies on the flexural capacity of the strengthened beam are also examined. The flexural rigidity of the strengthened beam was enhanced compared with RC beam. In addition, the failure mode and load-deflection relationship for the strengthened beam and the comparison of analysis with experiment are extensive investigated. Finally, the determination of the nominal moment capacity $M_n$ of the strengthened beam will be discussed

• 콘크리트학회논문집
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• 제29권3호
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• pp.291-298
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• 2017

이 연구에서는 강재 기둥과 접합된 하이브리드 H-보-철근 콘크리트 보(HSRC)의 반복 휨 거동을 평가하였다. 실험 변수는 HSRC 보의 연결절점에 배근되는 장부철근의 유무이다. HSRC 보의 소성힌지는 RC 보보다는 기둥 접합부 부근의 H-보에서 형성되도록 유도하였다. 모든 실험체는 하중의 급격한 감소 없이 연성적인 거동을 보였으며, 비록 예상치 못한 H-기둥과 H-보 용접 접합부의 파괴가 발생하였지만, 결과적으로 4.6 이상의 변위연성비를 나타내었다. HSRC 보 시스템에서 RC 보의 균열진전, 휨 강도 및 연성에 대한 장부철근의 영향은 매우 미미하였다. HSRC 보 시스템의 휨 강도는 단면의 완전소성으로 가정하여 산정한 H-보의 최대 휨 내력에 비해 안전 측에서 평가될 수 있었다.

• 산업기술연구
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• 제26권B호
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• pp.101-110
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• 2006

The purpose of this study was to investigate the flexural, interfacial behavior, crack propagation, nonlinear behavior, effect repaired and rehabilitated with VES-LMC using RC beam with 4-point-loading test. The results were following: The test result showed that repair and rehabilitation effect increased as its depth increased, which was verified by the increase of flexural stiffness. More than 40% of stiffness was improved when the depth of repair was up to steel position. However, there was a little difference between 8cm and 12cm repaired beam. This means the repair depth must be considered. The interfacial behavior data showed that the repaired or rehabilitated beams had a little relative displacement. This means that two materials behave comparatively acting together. This suggested that interface treatment were one of the most important jobs in composite beams.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.421-426
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• 2003

For the replacement of deteriorated concrete decks or wider-span slab, composite slab could be very attactive due to higher stiffness and strength. Based on the previous research, a modified I-beam composite hollow slab was suggested. In order to investigate the static flexural behavior of the proposed composite slab and to suggest its flexural design method, experiments were performed. Judging from the tests, a composite slab with I-beam having a semi-circle hole showed better structural performance. The effect of web details on the flexural stiffness was negligible. Flexural stiffness, ultimate strength, and ductility of the composite slabs were significantly greater than the RC slab due to composite action. While the failure of the RC slab was punching shear failure, the composite hollow slab showed flexural cracking and failure by yielding of the I-beams and crushing of concrete. Therefore, the current one-way design concept is appropriate for the design of I-beam composite hollow slab.

• Structural Engineering and Mechanics
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• 제52권2호
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• pp.427-443
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• 2014

This paper presents detailed analysis of the internal forces of interior beam-column joints of reinforced concrete (RC) frames under seismic action, identifies critical joint sections, proposes consistent definitions of average joint shear stress and average joint shear strain, derives formulas for calculating average joint shear and joint torque, and reports simplified analysis of the effects of joint shear and torque on the flexural strengths of critical joint sections. Numerical results of internal joint forces and flexural strengths of critical joint sections are presented for a pair of concentric and eccentric interior connections extracted from a seismically designed RC frame. The results indicate that effects of joint shear and torque may reduce the column-to-beam flexural strength ratios to below unity and lead to "joint-yielding mechanism" for seismically designed interior connections. The information presented in this paper aims to provide some new insight into the seismic behavior of interior beam-column joints and form a preliminary basis for analyzing the complicated interaction of internal joint forces.

• 한국철도학회논문집
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• 제12권3호
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• pp.388-395
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• 2009

유리섬유시트로 보강된 철근콘크리트 보의 휨 거동을 조사하기 위해, 하나의 기준보와 8개의 보강보(4개의 NU-보강보, 4개의 U-보강보)에 대한 보강보 휨 실험을 수행하였다. NU 보강보는 단부에 U 밴드를 적용하지 않은 보를, U-보강보는 U 밴드를 가진 보를 의미한다. 보강보 실험에서의 실험변수들은 유리섬유시트의 보강 양, U 밴드의 유무 등이 있다. 기준보와 비교하여 NU 보강보와 U 보강보의 최대하중은 각각 48%와 34% 증가하였으며, 휨 강성은 각각 920%와 880% 증가하였다. NU 보강보와 U 보강보에 대한 연성지수는 1.43에서 2.60 사이에 놓여있다. U 밴드를 가진 보강 시스템은 섬유시트의 계면박리 파괴를 지연시키고, U 밴드가 없는 보강시스템보다 나은 연성거동을 나타내 보였다. NU 보강보와 U 보강보 모두에서 섬유시트 겹수의 증가에 따라 최대하중과 휨 강성은 증가하였다. 실험결과들을 이론적인 비선형 휨 해석결과와 비교하였으며, 잘 일치함을 확인하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.543-548
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• 2003

In this study, a numerical model is developed using axial deformation link elements that can effectively predict the failure behavior of RC type structures. Using this mod 1, numerical analysis was performed to investigate the strengthening effect and failure behavior of structures repaired with a new material. High-Performance Cementitious Composites, which is characterized by its ductility with 5% strain-capacity is used as a repair material. To investigate the validity of developed numerical model, simulations of direct tension specimen and flexural specimen are performed and the results are compared with published ones. The similar analysis is performed for RC beam. Through this study, it is seen that predicted response has a good agreement with the experimental results. Using this verified numerical model, the strengthening effect of repaired with HPCC structure is analyzed through load-displacement curve and failure modes. Also, the same numerical analysis is performed in RC beam repaired with HPCC. The effect of HPCC ductility is estimated for the overall behavior of structures. Based on the results, the fundamental data are suggested for repaired structures with HPCC.