• Computers and Concrete
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• v.26 no.6
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• pp.515-531
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• 2020

Due to the construction difficulties of steel reinforced concrete (SRC), a new composite structure of steel and steel fiber reinforced concrete (SSFRC) is proposed for solving construction problems of SRC. This paper aims to investigate the bond properties and composition of interfacial bond stress between steel and steel fiber reinforced concrete. Considering the design parameters of section type, steel fiber ratio, interface embedded length and concrete cover thickness, a total of 36 specimens were fabricated. The bond properties of specimens were studied, and three different methods of calculating interfacial bond stress were analyzed. The results show: relative slip first occurs at the free end; Bearing capacity of specimens increases with the increase of interface embedded length. While the larger interface embedded length is, the smaller the average bond strength is. The average bond strength increases with the increase of concrete cover thickness and steel fiber ratio. And calculation method 3 proposed in this paper can not only reasonably explain the hardening stage after the loading end curve yielding, but also can be applied to steel reinforced high-strength concrete (SRHC) and steel reinforced recycled coarse aggregate concrete (SRRAC).

• Journal of the Korea Concrete Institute
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• v.13 no.6
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• pp.584-592
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• 2001

The cracks are developed in reinforced concrete(RC) beams at the early stage of service load because of the relatively small tensile strength of concrete. The structural strength and stiffness are decreased by reduction of tensile resistance capacity of concrete due to the developed cracks. Using the fiber reinforced concrete that is increased the flexural strength and tensile strength at tensile part can enhance the strength and stiffness of concrete structures and decrease the tensile flexural cracks and deflections. Therefore, the RC beams used of the fiber reinforced concrete at. tensile part ensure the safety and serviceability of the concrete structures. In this work, analytical model of a dual concrete beams composed of the normal strength concrete at compression part and the high tension strength concrete at tensile part is developed by using the equilibrium conditions of forces and compatibility conditions of strains. Three groups of test beams that are formed of one reinforced concrete beam and two dual concrete beams for each steel reinforcement ratio are tested to examine the flexural behavior of dual concrete beams. The comparative study of total nine test beams is shown that the ultimate load of a dual concrete beams relative to the RC beams is increased in approximately 30%. In addition, the flexural rigidity, as used here, referred to the slope of load-deflection curves is increased and the deflection is decreased.

• Steel and Composite Structures
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• v.50 no.3
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• pp.249-263
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• 2024

This article presents a comparative analysis of seismic behavior in steel-beam reinforced concrete column (RCS) frames versus steel and reinforced concrete frames. The study evaluates the seismic response and collapse behavior of RCS frames of varying heights through nonlinear modeling. RCS, steel, and reinforced concrete special moment frames are considered in three height categories: 5, 10, and 20 stories. Two-dimensional frames are extracted from the three-dimensional structures, and nonlinear static analyses are conducted in the OpenSEES software to evaluate seismic response in post-yield regions. Incremental dynamic analysis is then performed on models, and collapse conditions are compared using fragility curves. Research findings indicate that the seismic intensity index in steel frames is 1.35 times greater than in RCS frames and 1.14 times greater than in reinforced concrete frames. As the number of stories increases, RCS frames exhibit more favorable collapse behavior compared to reinforced concrete frames. RCS frames demonstrate stable behavior and maintain capacity at high displacement levels, with uniform drift curves and lower damage levels compared to steel and reinforced concrete frames. Steel frames show superior strength and ductility, particularly in taller structures. RCS frames outperform reinforced concrete frames, displaying improved collapse behavior and higher capacity. Incremental Dynamic Analysis results confirm satisfactory collapse capacity for RCS frames. Steel frames collapse at higher intensity levels but perform better overall. RCS frames have a higher collapse capacity than reinforced concrete frames. Fragility curves show a lower likelihood of collapse for steel structures, while RCS frames perform better with an increase in the number of stories.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.499-504
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• 1998

Objective of this study is to investigate experimentally the flexural behavior of reinforced high-strength concrete beams with Belite cement by comparing with those of normal reinforced concrete beams. The flexural tests are conducted on fourteen specimens having concrete compressive strength of 350 and 600kg/$\textrm{cm}^2$. The main experimental variables are compressive strength of concrete and reinforcement ratios. The load-displacement relationships, the section behavior of beam as a function of the location neutral axis, and ductility capacity are investigated. From the test results, the flexural behavior of reinforced high-strength concrete beams wite Belit cement are similar to the behavior of normal reinforced concrete beams.

• Computers and Concrete
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• v.12 no.6
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• pp.819-829
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• 2013

The objective of this study is to determine whether or not the yield line theory, an effective method widely used for slabs made of ordinary concrete, can be used also for the reinforced concrete slabs made of high-strength concrete. Flexural behavior of simply supported slabs in three different sizes were investigated under concentrated load at mid-span. Additionally, behavior of high strength reinforced concrete slabs with 50 mm and 150 mm reinforcement spacings also studied. Failure loads, deflections, experimental and theoretical failure mechanisms were evaluated. The difference between the moments based on yield line theory and experimental moments varied between 1% to 3%. Experimental and analysis results revealed that yield line analysis could conveniently be employed in the analysis of high strength reinforced concrete slabs.

• Journal of the Korea Concrete Institute
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• v.12 no.3
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• pp.57-66
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• 2000

The ductility is an important consideration in the design of reinforced concrete structures. In the seismic design of reinforced concrete columns, it is necessary to allow for relatively large ductilities that the seismic energy be absorbed without shear failure of significant strength degradation after the reinforcement yielding in columns. Therefore, prediction of the ductility should be as accurate as possible. This research investigate the ductile behavior of rectangular reinforced high-strength concrete columns like as bridge piers with confinement steel. The effects on the ductility of axial load, lateral reinforcement ratio, longitudinal reinforcement ratio, shear span ratio, and compressive strength of concrete were investigated analytically using layered section analysis. as the results, it was proposed the proper relationship between ductility and variables and formulated into equations.

• International Journal of Concrete Structures and Materials
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• v.1 no.1
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• pp.3-9
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• 2007

Fiber-reinforced self-compacting concrete (FRSCC) is a new type of concrete mix that can mitigate two opposing weaknesses: poor workability in fiber-reinforced concrete and cracking resistance in plain SCC concrete. This study focused on early-age cracking of FRSCC due to restrained drying shrinkage, one of the most common causes of cracking. In order to investigate the effect of fiber on shrinkage cracking of FRSCC, ring shrinkage tests were performed for polypropylene and steel fiber-reinforced SCC. In addition, finite element analyses for those specimens were carried out considering drying shrinkage based on moisture diffusion, creep, cracking resistance of concrete, and the effect of fiber. The analysis results were verified via a comparison between the measured and calculated crack width. From the test and analysis results, the effectiveness of fiber with respect to reducing cracking was confirmed and some salient features on the shrinkage cracking of FRSCC were obtained.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.718-723
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• 2000

Reinforced concrete is in general, known as high durability construction material under normal environments due to strong alkalinity of cement. It is, however, well known that moderate or minor cracks in reinforced concrete should be most serious causes to deteriorate the durability of RC structures. Futhermore, chloride contents penetrating through unexpected cracks in reinforced concrete bridges get to weaken corrosion resistance of reinforcement steel in concrete and then to accelerate the deterioration of concrete durability. The objective of this experimental research is 1) to evaluate the effect of various corrosion protection systems for reinforced concrete specimens with moderate or minor cracks which are exposed to cyclic wet and dry seawater, and then 2) to develop effective corrosion protection systems for reinforced concrete bridges under the exposure of various detrimental environments such as seawater, deicing and etc.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.287-292
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• 1997

Recent economic growths have accelerating much construction activities of various infrastructures, such as Express railway, Long-span bridges, Multi-story Buildings and etc. Reinforcement steel corrosion to be inevitably caused under the progress of these construction activities have been on and off serious problems in the site, which could incur another tragedic accident to us suffering from safety-ignorance disease. Thus, it is strongly requested to develop probable innovative products which could remove corrosive materials on rebars and also protect steel corrosion of reinforced concrete structures in the construction site. Hydro-Seal and Steel-Seal could solve these problems currently faced with in the construction site. The objective of this research is to experimentally evaluated the effect of Hydro-Seal and Steel-Seal in reinforced concrete structures, of which usage might affect the bond strength between steel and concrete, long-term compressive strength of concrete, corrosion resistance and etc. Related test results show that appropriate dosage of Hydro-Seal and Steel-Seal in reinforced concrete structures didnot affect physical properties of reinforced concrete structures.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.797-802
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• 1998

Fiber reinforcement can significantly improve the properties of concrete. Particulary, toughness or energy-absorbing ability of fiber reinforced concrete is frequently higher than that of unreinforced concrete. Toughness is a measure of energy absorption capacity and used to characterized fiber reinforced concrete's ability to resist fracture when subjected to static, dynamic and impact loads. However, the current standard methods of characterizing the toughness of fiber reinforced concrete have proven to be some inadequate and problems and have caused a great deal of dissent and confusion. This study research some of the inadequate and problems with these toughness measurement methods and proposes the evaluation method for Fiber Reinforced Concrete toughness.