• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.565-570
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• 1997

This study is on the strength capacity and the strengthening effects of crarbon fiber sheets(CFS) and glass fiber sheets (GFS) on steel reinforced concrete(SRC) beams. SRC beams are often used on high-rise building construction to save story height and construction cost. However, there are no strengthening design code in Korea and most engineers design it as steel beams ignored the composite effect if reinforced concrete. Test results on steel reinforced concrete beams reveal thar the strength capacity of SRC beam is more than simple addition of steel and reinforced concrete beams. In case of steel reinforced concrete beams, ultimate moment capacity of strengthening beam of carbon fiber sheets is 120% of non-strengthening one.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.393-396
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• 2004

The objective of this experimental study is to understand the shear behavior of reinforced concrete continuous deep beams. The main variables considered were concrete strength and shear span-to-depth ratio. Specimens of 4 two-span continuous deep beams were tested and compared with the strength of simple span beams. The results show that the influence of concrete strength on the shear strength of continuous deep beams is comparable to that on simple span deep beams. However, the effect of span-to-depth ratio is significantly greater than simple span deep beams.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.339-342
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• 2005

This paper presents flexural test results of concrete beams reinforced with GFRP and conventional steel reinforcement for comparison. The beams were tested under static loading to investigate the effects of reinforcement ratio and compressive ,strength of concrete on cracking, deflection, ultimate capacity and mode of failure, This study attempts to establish a theoretical basis for the development of simple and rational design guideline. Test results show that ultimate capacity increases as the reinforcement ratio and concrete strength increase. The ultimate capacity increased up to $8\%-25\%$ by using high strength concrete. The deflection at maximum load of GFRP reinforced beams was about three times that of steel reinforced beams. For GFRP-reinforced beams, the ACI code 440 design method resulted in conservative flexural strength -estimates.

• Computers and Concrete
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• v.1 no.2
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• pp.115-130
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• 2004

The flexural ductility of solid rectangular reinforced concrete beams has been studied quite extensively. However, many reinforced concrete beams are neither solid nor rectangular; examples include T-, ${\Gamma}$-, ${\Pi}$- and box-shaped beams. There have been few studies on the flexural ductility of non-rectangular reinforced concrete beams and as a result little is known about the possible effect of sectional shape on flexural ductility. Herein, the effect of sectional shape on the post-peak flexural behaviour of reinforced normal and high-strength concrete beams has been studied using a newly developed analysis method that employs the actual stress-strain curves of the constitutive materials and takes into account the stress-path dependence of the stress-strain curve of the steel reinforcement. It was revealed that the sectional shape could have significant effect on the flexural ductility of a concrete beam and that the flexural ductility of a T-, ${\Gamma}$-, ${\Pi}$- or box-shaped beam is generally lower than that of a solid rectangular beam with the same overall dimensions and the same amount of reinforcement provided. Based on the numerical results obtained, a simple method of ensuring the provision of a certain minimum level of flexural ductility to non-rectangular concrete beams has been developed.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.72-75
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• 2004

Carbon Fiber Reinforced Polymer(CFRP) composites are widely applied to strengthen deteriorated concrete structures. This paper presents the experimental results of the performance of reinforced concrete(RC) beams strengthened with externally prestressed CFRP plates. Simple beams with 3 m span length were tested to investigate the effect of prestressing force of CFRP plates on the flexural behavior of externally strengthened RC beams.

• International Journal of Concrete Structures and Materials
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• v.8 no.1
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• pp.83-97
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• 2014

This paper presents the results of an investigation aimed at developing reinforced concrete beams consisting of precast permanent U-shaped reinforced mortar forms filled with different types of core materials to be used as a viable alternative to the conventional reinforced concrete beam. To accomplish this objective, an experimental program was conducted and theoretical model was adopted. The experimental program comprised casting and testing of thirty beams of total dimensions $300{\times}150{\times}2,000mm$ consisting of permanent precast U-shaped reinforced mortar forms of thickness 25 mm filled with the core material. Three additional typical reinforced concrete beams of the same total dimensions were also cast to serve as control specimens. Two types of single-layer and double-layers steel meshes were used to reinforce the permanent U-shaped forms; namely welded wire mesh and X8 expanded steel mesh. Three types of core materials were investigated: conventional concrete, autoclaved aerated lightweight concrete brick, and recycled concrete. Two types of shear connections between the precast permanent reinforced mortar form and the core material were investigated namely; adhesive bonding layer between the two surfaces, and mechanical shear connectors. The test specimens were tested as simple beams under three-point loadings on a span of 1,800 mm. The behavior of the beams incorporating the permanent forms was compared to that of the control beams. The experimental results showed that better crack resistance, high serviceability and ultimate loads, and good energy absorption could be achieved by using the proposed beams which verifies the validity of using the proposed system. The theoretical results compared well with the experimental ones.

• Computers and Concrete
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• v.21 no.1
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• pp.95-102
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• 2018

Reinforced concrete corbel beams (span to depth ratio of a corbel is less than one) are designed with primary reinforcement bars to account for bending moment and with the secondary reinforcement placed parallel to the primary reinforcement (shear stirrups) to resist shear force. It is interesting to note that most of the available analytical procedures employ empirical formulas for the analysis of reinforced concrete corbels. In the present work, a generalized and a simple strut and tie models were employed for the analysis of reinforced corbel beams. The models were benchmarked against experimental results available in the literature. It was shown here that increase of shear stirrups increases the load carrying capacity of reinforced concrete corbel beams. The effect of horizontal load on the load carrying capacity of the corbel beams has also been examined in the present paper. It is observed from the strut and tie models that the resistance of the corbel beam subjected to combined horizontal and vertical load did not change with increase in shear stirrups if the failure of the corbel is limited by concrete crushing. In other words, the load carrying capacity was independent of the horizontal load when failure of the beam occurred due to concrete crushing.

• Coupled systems mechanics
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• v.8 no.4
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• pp.289-298
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• 2019

Reinforced concrete can be considered as a heterogeneous material consisting of coarse aggregate, mortar mix and reinforcing bars. This paper presents a two-dimensional mesoscopic analysis of reinforced concrete beams using a simple two-phase mesoscopic model for concrete. The two phases of concrete, coarse aggregate and mortar mix are bonded together with reinforcement bars so that inter force transfer will occur through the material surfaces. Monte Carlo's method is used to generate the random aggregate structure using the constitutive model at mesoscale. The generated models have meshed such that there is no material discontinuity within the elements. The proposed model simulates the load-deflection behavior, crack pattern and ultimate load of reinforced concrete beams reasonably well.

• Advances in concrete construction
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• v.10 no.2
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• pp.93-104
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• 2020

Basalt fiber is an eco-friendly fiber and comparatively newer to the world of fiber-reinforced polymer (FRP) composites. A limited number of studies have been reported in the literature on the strengthening of reinforced concrete (RC) beams with basalt fiber reinforced polymer (BFRP). The present experimental work explores the feasibility of using the BFRP strips for shear strengthening of the RC beams. The strengthening schemes include full wrap and U-wrap. A simple mechanical anchorage scheme has been introduced to prevent the debonding of U-wrap as well as to utilize the full capacity of the BFRP composite. The effect of varying shear span-to-effective depth (a/d) ratio on the behavior of shear deficient RC beams strengthened with BFRP strips under different schemes is examined. The RC beams were tested under a four-point loading system. The study finds that the beams strengthened with and without BFRP strips fails in shear for a/d ratio 2.5 and the enhancement of the shear capacity of strengthened beams ranges from 5% to 20%. However, the strengthened beams fail in flexure, and the control beam fails in shear for a higher a/d ratio, i.e., 3.5. The experimental results of the present study have been compared with the analytical study and found that the latter gives conservative results.

• Structural Engineering and Mechanics
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• v.23 no.6
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• pp.713-737
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• 2006

This paper presents the results of an experimental investigation on the behaviour of 56 reinforced concrete beams subjected to pure torsion. The reported results include the behaviour curves, the failure modes and the values of the pre-cracking torsional stiffness, the cracking and ultimate torsional moments and the corresponding twists. The influence of the volume of stirrups, the height to width ratios and the arrangement of longitudinal bars on the torsional behaviour is discussed. In order to describe the entire torsional behaviour of the tested beams, the combination of two different analytical models is used. The prediction of the elastic till the first cracking part is achieved using a smeared crack analysis for plain concrete in torsion, whereas for the description of the post-cracking response the softened truss model is used. A simple modification to the softened truss model to include the effect of confinement is also attempted. Calculated torsional behaviour of the tested beams and 21 beams available in the literature are compared with the experimental ones and a very good agreement is observed.