• Journal of the Korea Concrete Institute
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• v.11 no.3
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• pp.171-179
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• 1999

The present research investigated the interaction among loading level, corrosion rate and flexural deflection of reinforced concrete beams. 10cm$\times$15cm$\times$110cm reinforced concrete beams were prepared and subjected to different levels of flexural loading, including 0%, 45% and 75% of the ultimate load. The beams with either a pre-load or a sustained load were also exposed to a laboratory environment with ponding and wetting/drying cycling at room temperature. Half cell potential and galvanized current measurements were taken to monitor corrosion process of reinforcing steel. After corrosion initiation, external current was applied to some of the beams to accelerate corrosion propagation. The beam deflections were recorded during the entire tests. The results indicate that loading level has significant effect on corrosion rate. The beams under a sustained load had much higher corrosion rate than the pre-loaded and then unloaded beams. Significant corrosion may result in an increase in beam deflection and affect serviceability of the structure. The present research may provide an insight into structural condition evaluation and service life predictions of reinforced concrete.

• Steel and Composite Structures
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• v.2 no.4
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• pp.259-276
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• 2002

In the present investigation the experimental and theoretical flexural and compressive behavior of short tubular steel columns filled with plain concrete and fiber-reinforced concrete (FRC) was examined. For a given length of the members, the effects of different geometry and dimensions of the transverse cross-section (square and circular) were investigated. Constituent materials were characterized through direct tensile tests on steel coupons and through compressive and split tension tests on concrete cylinders. Load-axial shortening and load-deflection curves were recorded for unfilled and composite members. Finally, simplified expressions for the calculus of the load-deflection curves based on the cross-section analysis were given and the ultimate load of short columns was predicted.

• Structural Engineering and Mechanics
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• v.27 no.4
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• pp.501-521
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• 2007

This study presents a model to better understand the shear behavior of reinforced concrete walls subjected to lateral load. The scope of the study is limited to squat walls with height to length ratios not exceeding two, deformed in a double-curvature shape. This study is based on limited knowledge of the shear behavior of low-rise shear walls subjected to double-curvature bending. In this study, the wall ultimate strength is defined as the smaller of flexural and shear strengths. The flexural strength is calculated using a strength-of-material analysis, and the shear strength is predicted according to the softened strut-and-tie model. The corresponding lateral deflection of the walls is estimated by superposition of its flexibility sources of bending, shear and slip. The calculated results of the proposed procedure correlate reasonably well with previously reported experimental results.

• Journal of the Korean Ceramic Society
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• v.29 no.11
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• pp.893-899
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• 1992

Composite specimens, which are composed MDF cement of HAC-PVA system were prepared by adding carbon fiber, hydrated silica and SiC powder, and we studied effect of additives on the flexural strength of the composites. All of additives is effective in the improvement of flexural strength of the composite specimens. The size of average pore diameter in the specimens which have high flexural strength property was small. Specimen mixed with hydrated silica was effective in the particle compact property. Flexural strength of carbon fiber reinforced MDF cement composites were improved because of crack deflection of carbon fiber in cementitious matrix.

• Computers and Concrete
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• v.21 no.2
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• pp.157-166
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• 2018

This article presents the flexural behaviour of reinforced fly ash (FA)-based geopolymer concrete (GPC) beams with partial replacement of FA for about 10% by weight with paper sludge ash (PSA). The beams were made of M35 grade concrete and cured under three curing conditions for comparison viz., ambient curing, external exposure curing, and oven curing at $60^{\circ}C$. The beams were experimentally tested at the 28th day of casting after curing by conducting two-point loading flexural test. Performance aspects such as load carrying capacity, first crack load, load-deflection and moment-curvature behaviours of both types of beams were experimentally studied and their results were compared under different curing conditions. To verify the response of reinforced GPC beams numerically, an ANSYS 13.0 finite element program was also used. The result shows that there is a good agreement between computer model failure behaviour with the experimental failure behaviour.

• Structural Engineering and Mechanics
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• v.38 no.4
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• pp.459-477
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• 2011

Due to the low elastic modulus of FRP, concrete members reinforced with FRP rebars show greater deflections than members reinforced with steel rebars. Deflection is one of the important factors to consider the serviceability of horizontal members. In this study flexural test of AFRP reinforced concrete beams was performed considering reinforcement ratio and compressive strength as parameters. The test results indicated that flexural capacity and stiffness increase in proportion to the reinforcement ratio. The test results were compared with existing proposed equations for the effective moment of inertia including ACI 440. The most of the proposed equations were found to over-estimate the effective moment of inertia while the equation proposed by Bischoff and Scanlon (2007) most accurately predicted the values obtained through actual testing.

• 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.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.05a
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• pp.206-211
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• 2004

This paper deals with the flexural strengthening of reinforced concrete beams by means of thin fiber reinforced plastic(FRP) laminas. This study focuses on modeling of structural of concrete bonded FRP laminate in flexural bending members. Used computational equation is derived by relation of stress and strain. The section analysis is based on experimental observations of a linear strain distribution in the cross section until failure, and a multi-linear moment-deflection curve that is divided into four regions, each terminated by a similarly numbered point. The load-deflection relationship in each region is assumed to be linear. The present model is validated to compare wit the experiment of 4-point bending tests of R/C rectangular beams strengthened with CFRP laminates, and has well predicted the moment-displacement relationships of members.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.413-416
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• 2004

This paper describes a proposal for crack width and deflection in RC flexural members. Because the serviceability provisions of the current codes are mainly based on only empirical relationships developed from test result and effective moment of inertia, crack width and deflections are contrary to the actual values. Based on nonlinear bond characteristics, tension stiffening effect, arch action and effective concrete tensile area. Then an equation is developed for predicting crack width and deflection in flexural members. The predicted results shows that as proposed model employed, crack width and deflections are different from estimated by the current KCI, MC 90 and EC 2 provisons, and the values predicted are in good agreement with experimentally measured values.

• Structural Engineering and Mechanics
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• v.87 no.3
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• pp.201-210
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• 2023

This paper investigates the flexural behavior of reinforced recycled aggregates concrete (RRAC) beams after exposed to high temperatures. The experimental results from 17 specimens were present and compared with temperatures, recycled coarse aggregate (RCA) replacement percentages, and concrete strength as variables. It was found that the high temperature would not cause an observable change in the failure pattern. However, high temperature can significantly reduce the stiffness and ductility, and accelerate the damage degradation of specimens. After exposure to 600℃, the ultimate bearing capacity of the specimens decreased by 20%-30% The mechanical properties of RRAC beams after high temperatures were barely impacted by the replacement percentages. Increasing the concrete strength of RCA could effectively improve the bearing capacity and peak deflection of RRAC beams after exposed to high temperatures. Furthermore, the calculation method of the bending bearing capacity and deflection of RRAC beams was also discussed.