• Journal of the Korea Concrete Institute
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• v.12 no.2
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• pp.71-78
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• 2000

This paper presents a study on the flexural rigidity of reinforced high strength concrete beams. Thirty six beams with different compressive strength of concrete, tensile reinforcement ratio, compressive reinforcement ratio, and pattern of loadings(1 point loading and 2 points loading) were tested to evaluate the effective moment of inertia. According to the experimental results, the eqation(1) proposed by ACI code for the effective moment of inertia overestimated that of simply supported reinforced high strength concrete beams. Thus, in this paper, an empirical equation(3) is proposed as a lower bound of 90% confidence limit to estimate the effective moment of inertia of simply supported reinforced high strength concrete beams.

• International Journal of Concrete Structures and Materials
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• v.3 no.1
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• pp.39-45
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• 2009

The purpose of this study is to establish flexural behavior of high-strength concrete beams confined in the pure bending zone with stirrups. The experiment was carried out on full-scale high-strength reinforced concrete beams, of which the compressive strengths were 40 MPa and 70 MPa. The beams were confined with rectangular closed stirrups. Test results are reviewed in terms of flexural capacity and ductility. The effect of web reinforcement ratio, longitudinal reinforcement ratio and shear span to beam depth ratio on ductility are investigated. The analytic method is based on finite element method using fiber-section model, which is known to define the behavior of reinforced concrete structures well up to the ultimate state and is proven to be valid by the verification with the experimental results above. It is found that confinement of concrete compressive regions with closed stirrups does not affect the flexural strength but results in a significantly increased ductility. Moreover, the ductility tends to increase as the quantity of stirrups increases by reducing the spacing of stirrups.

• Computers and Concrete
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• v.11 no.2
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• pp.105-121
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• 2013

This paper investigates the parameters that control the design of Fiber Reinforced Polymer (FRP) reinforced concrete flexural members proportioned following the ACI 440.1R-06. It investigates the critical parameters that control the flexural design, such as the deflection limits, crack limits, flexural capacity, concrete compressive strength, beam span and cross section, and bar diameter, at various Mean-Ambient Temperatures (MAT). The results of this research suggest that the deflection and cracking requirements are the two most controlling limits for FRP reinforced concrete flexural members.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.567-572
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• 1999

Experimental study was conducted to investigate the flexural-shear behavior of hooked steel fiber reinforced high strength concrete (SFRHC) beams. Twenty beams with shear span-depth ratio of 1.45 were tested, of which variables were the contents of steel fiber with aspect ratio of 60, tension reinforcement ratio and concrete compressive of 60MPa and 80MPa. Test results has shown that shear failure of the beams were changed into flexural-shear failure or flexural failure according to increasing steel fiber content, that SFRHC with slump of 15cm over and fiber volume ratio of 1.5% was possible in practice, and that proper volume ratio of steel fiber was 1.5%.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.1
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• pp.43-50
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• 2010

To address the problems caused by the corrosion of steel rebar, active research has recently been carried out on members where fiber-reinforced polymer (FRP) is used in place of rebar. As FRP bar is highly brittle and has a low modulus of elasticity, further research is needed on the evaluation of serviceability, in other words on the deflection of flexural concrete members reinforced with FRP rebars. Taking the reinforcement ratio as a variable, this paper analyzes the flexural capacity of concrete beams reinforced with CFRP rebar. The test results of specimens reinforced with CFRP rebar show an increase in stiffness and resisting force along with an increase in the reinforcement ratio. A reinforcement ratio of about 1.3 is needed for the member reinforced with CFRP rebar to show same section property of a steel member. Through a comparison for the value of an effective moment of inertia, the equation suggested by Bischoff & Scanlon predicted values closest to the actual results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.6 s.58
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• pp.106-114
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• 2009

The basis principle of conservation about deterioration and corrosion of cultural assets building is the archetype maintenance, and should not make a factitious damage mistake by repair. Accordingly, conservation processing method using synthetic resins is embossed. The purpose of this paper is about flexural capacity of rectangular section wood using synthetic resins, the 11 specimens are manufactured and made an experiment about reinforcement length, ratio, material strength, direction of synthetic resins as variable. The results of this paper has shown that flexural reinforcement of wood by synthetic resins are efficient and found the possibility of using.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.8
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• pp.3745-3751
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• 2011

In this study flexural strength of damaged concrete beams reinforced by CFS is analysed. Nonlinear section analysis is used to include stress status of tension bars and compressive concrete under loads acting on the original member at the time of strengthening. Calculated flexural strength is compared with Sin-Hong formula which is frequently used in CFS reinforcement design. Nonlinear analysis with variation of the number of strengthening CFS, the ratio of tensile reinforcement, the ratio of section dimension shows that the flexural strength of CFS reinforced beams much depends on reinforcing stage. From the result of this analysis, the flexural strength of CFS reinforced concrete beam is reduced according to the magnitude of pre-loaded service loads.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.36 no.4
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• pp.123-133
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• 2020

The purpose of this study is to analyze the method of retrofitting flexural strength and the flexural performance of retrofitted shear walls. There are various ways to reinforce the flexural strength of reinforced concrete shear wall structural systems that have already been built, in the case of that, the external force is increased, and the internal force is insufficient. However, there are various problems, such as excessive flexural stiffness after reinforcement and increasing the thickness and length of the wall. We have developed a retrofit method to solve these problems. The wall end is excavated to place the required vertical rebars, and concrete is poured after placing rebars. This is the same concept as creating wall end boundary elements later on. We also studied the anchorage method of reinforcement and the interaction method between the retrofitting end and the existing wall. The flexural test results for the reinforced concrete shear wall using the studied retrofit method can be predicted according to the sectional analysis and FEM analysis, and there are differences in the plastic hinge length, crack propagation, stiffness degradation and energy dissipation due to the bending depending on the vertical rebar ratio of wall end.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.701-704
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• 1999

The purpose of this study was to investigate the effectiveness of the flexural rehabilitation of the pre-loaded reinforced concrete beams strengthened by the steel plate. Main test parameters were the existence and the magnitude of the pre-loading at the flexural of rehabilitation and the tensile reinforcement ratio of the specimens. Seven beam specimens were tested to investigate the effectiveness of the rehabilitation method. Test results showed that the ultimate load capacities of the pre-loaded specimens were higher than not-pre-loaded specimens at the rehabilitation. The cause of the pharameter was analyzed if is suggested that the bond failure between the concrete and the strengthening steel plate occured prior to the yielding of the tension reinforcement. The member flexural stiffnesses, were similar regardless of the load conditions at retrofit and failure modes showed brittle aspect caused by rip-off failure.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.733-738
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• 2000

This paper was aimed to evaluate the structural performance of flexural members repaired by polymer cement and epoxy mortar at soffit. Main test variables were repair materials, ratio of reinforcement and additional reinforcing bars. Test results shows that the repaired beams could change flexural capacity by materials and additional reinforcing bars. In polymer cement, the section repaired can carry same load, cracking moment and the flexural stiffness of the monolithic beams with same size. In epoxy mortar, all data were greater than the shotcrete. However, note that epoxy mortar may conduct member into brittle failure mode.