• Proceedings of the Computational Structural Engineering Institute Conference
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• 1991.04a
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• pp.3-7
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• 1991

Considering the relatively large amount of stable flexural teat results available for steel fiber reinforced concrete (SFRC) and their dependency on the constitutive behavior of the material, a technique called “System Identification” is used for interpretating the flexural test data in order to obtain basic information on the tensile constitutive behavior of steel fiber reinforced concrete. “System Identification” was successful in obtaining optimum sets of parameters which provide satisfactory matches between the measured and predicted flexural load-deflection relationships.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.845-850
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• 1998

Flexural tests on 3.0m reinfored concrete beams with epoxy and anchor bolt bonded CFRF-Grid reported in these tests. The selected experimental variables are concrete compressive strength, strengthening length and strengthening method. The effects of these variables in overall behavior are discussed. The results generally shown that the main flexural mode of strengthened beams is separation failure. The strengthening of the chipping by the tensile bar is really necessary in order to prevent CFRP-Grid from rip-off failure.

• Journal of Industrial Technology
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• v.22 no.A
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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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• v.30 no.3
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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.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.3
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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.

• Steel and Composite Structures
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• v.45 no.1
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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.

• Journal of the Korean Society for Railway
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• v.7 no.4
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• pp.319-325
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• 2004

In this study, analysis and design programs of bending of RC beams strengthened with fiber sheets are developed by using Visual Basic Language. The program consists two groups, ultimate strength method and nonlinear flexural analysis method. Ultimate strength method regards concrete compressive stress as a rectangular stress block and do not consider tensile stress of concrete and load-deflection curves. On the other hand, nonlinear flexural analysis considers tensile stress of concrete, load-deflection curves, state of stress distribution and failure strain of strengthening material. Also, the analysis method used in this study regards nonlinear flexural stress as compressive stress of concrete. This program can be a good tool for determining the bending strength of strengthened RC beams and estimating the amount of fiber sheets for practical use.

• Computers and Concrete
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• v.32 no.2
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• pp.173-184
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• 2023

In this study, mechanical, flexural post-cracking, and torsional behaviors of recycled steel fiber-reinforced concrete (RSFRC) incorporating steel fibers obtained from recycling of waste tires were investigated. Initially, three concrete mixes with different fiber contents (0, 40, and 80 kg/m³) were designed and tested in fresh and hardened states. Subsequently, the flexural post-cracking behaviors of RSFRCs were assessed by conducting three-point bending tests on notched beams. It was observed that recycled steel fibers improve the post-cracking flexural behavior in terms of energy absorption, ductility, and residual flexural strength. What's more, torsional behaviors of four RSFRC concrete beams with varying reinforcement configurations were investigated. The results indicated that RSFRCs exhibited an improved post-elastic torsional behaviors, both in terms of the torsional capacity and ductility of the beams. Additionally, numerical analyses were performed to capture the behaviors of RSFRCs in flexure and torsion. At first, inverse analyses were carried out on the results of the three-point bending tests to determine the tensile functions of RSFRC specimens. Additionally, the applicability of the obtained RSFRC tensile functions was verified by comparing the results of the conducted experiments to their numerical counterparts. Finally, it is noteworthy that, despite the scatter (i.e., non-uniqueness) in the aspect ratio of recycled steel fiber (as opposed to industrial steel fiber), their inclusion contributed to the improvement of post-cracking flexural and torsional capacities.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2A
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• pp.249-257
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• 2008

Various methods have been used to reinforce the cementitious material such as mortar and concrete that have weak tensile strength. Major reinforcing method is to mix matrix with fibers which have strong tensile strength. Recently, micro-fiber reinforced mortar has been studied which removes coarse aggregate and uses micro-fiber with small diameter in order to homogenize the matrix properties and maximize the performance of fiber. Performance of micro-fiber reinforced mortar showing multiple cracking behavior is hardly represented only by the flexural toughness. Therefore, This paper reports the cracking behavior as well as mechanical behavior for various mixtures which have different fiber type and mixture proportions to find the proper parameter representing the cracking characteristic. Correlations between flexural toughness and various cracking characteristics such as cracking area, width and number are explored. As a result, it is found that flexural toughness, volume of fiber and number of cracks are suitable for representing the characteristics of micro-fiber reinforced mortar.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.665-670
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• 2000

In this study mechanical properties of various fiber reinforced permeability concrete mixtures are investigated. Several mixes with fiber kinds(steel fiber, polyprophylen fiber, carbon fiber) and different fiber content(steel fiber : 0.3~0.9vol.%, polyprophylen fiber : 0.1~0.5vol.%, carbon fiber : 0.2~0.7vol.%) were studied. Test results are presented in terms of compressive strength, tensile-flexural strength and load-deflection behavior. The effect of fiber reinforcement does not increase the compressive strength of permeability concrete without fiber. Also, the tensile-flexural strength using various fibers are appeared good strength increase as conventional fiber reinforced concrete. Therefore, use of fiber for permeability concrete is necessary to improve of tensile-flexural properties and deformation performance(toughness).