• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.4
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• pp.157-167
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• 2002

In most cases, quantity of reinforcement is determined without regard to the difference of initial strain, and status of damages when calculated the strengthening in flexure at beams. Thus, the purpose of this study is to investigate the flexural strengthening efficiency and behavior of RC beams strengthened with carbon fiber sheets(CFS) considering different status of damages. in this paper, a nonlinear analysis program considering rip-off strength and residual stress of steel bars and concrete in different status of damages is developed to predict the flexural behavior of CFS strengthened beams. Rip-off strength equation is obtained by modifying moment of inertia in the Robert's equation. And conformed developed nonlinear analysis program in variable of strengthening CFS amount and status of damages(initial, case1, case2, case3) and tension reinforcement ratio(0.2~1.0%).

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.403-406
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• 2005

This paper deals with the propriety of the shear test data with stirrup reported in ACI and ASCE structural journal and the shear resistance characteristics affected by compressive strength of concrere($f_{ck}$), shear span-to-depth ratio (a/d), tensile reinforcement ratio($\rho$), and shear reinforcement ratio($rho_{v}$). The analysis was accomplished by the 242 shear test data. The test data include the flexural failure data around 40$\%$.

• International Journal of Concrete Structures and Materials
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• v.1 no.1
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• pp.45-55
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• 2007

Ten beams bonded with glass fiber reinforced polymer (GFRP) laminates were tested under cyclic loading with the load range and the FRP reinforcement ratio as test parameters. The maximum load level during cyclic loading was 55%, 65% and 75% of the static flexural strength while the minimum load level was kept constant at 35%. Deflections of the beams at the end of 525000 cycles were found to increase by 16% and 44% when the maximum load level was increased from 55% to 65% and 75% of the static flexural strength, respectively. Beams with FRP reinforcement ratios of 0.64% and 1.28% were found to exhibit lesser deflections of about 15% and 20%, respectively, compared to a similar beam without FRP reinforcement. An analytical approach based on cycle-dependent effective moduli of elasticity of concrete and FRP reinforcement is presented and found to predict the deflections of the test beams well.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.65-68
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• 2008

This is an experimental study on the out of plane load behavior of SC (Steel Plate Concrete) wall module under bending and shear loading. 4 tests were conducted to verify structural performance according to rib reinforcement ratio, stud reinforcement ratio and shear reinforcement ratio. On the basis of test results, it is found that rib reinforcement ratio is a main factor of flexural strength of SC structures.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.173-178
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• 1993

In order to quantify the effect of transverse reinforcement on the bond splitting behavior of reinforcement monotonic loading tests of 8 slmply beams were carried out. The reinforcing details and material properties were so determined that the bond splitting failure proceded the shear and flexural failure. A bond splitting strength derived from the experimental data and it accounts for following parameters: 1) Concrete Strength 2) Transverse reinforcement ratio and shape 3) Thickness of concrete cover 4)Deformation of reinforcement

• Proceedings of the Korea Concrete Institute Conference
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• 1992.10a
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• pp.185-190
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• 1992

ACI318-89 Recommended that when the specified compressive strength of concrete in a column is greater than1.4 times that specified for a floor system, top surface of the column concrete shall extend 2ft(600mm)into the slab from the face of column to avoid unexpected brittle failure. The major variables are extension distance, flexural strength ratio(Mr), and shear reinforcement ratio(Vs). Test results are as follows ; (1) The failure modes of specimens under cyclic loading were concentrated at critical region from beam-column joint face. (2) Ductility index($\mu$f) were increased with increasing of shear confinement ratio and flexural strength ratio. (3)The specimens with 2ft extension distance showed more ductility than the specimens with 1ft extension distance.

• Journal of the Korean Society of Safety
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• v.25 no.6
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• pp.128-136
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• 2010

In according with concrete structural design standard, it is common designing flexure reinforcement concrete to induce tension failure. So reinforcing ratio is limited to inducing tension failure. And maximum reinforcing ratio is regulated to protecting concrete compression strength caused by over reinforced building. Minimum reinforcing ratio is also limited in designing standard to protecting brittle failure as extremely using less reinforcing bar. But in minimum reinforcing ratio it is extremely conservative or it is sometimes impossible to induce stable tension-failure because they are depending on yield failure and experienced method and concrete designing standard strength. Therefore the purpose of the present paper is to evaluate the flexural behavior of minimum steel ratio of reinforced concrete of beams and to propose the guide-line of equation of minimum steel ratio by performing static flexural test of 16 beams according to size effect, number of steel, yielding stress of steel, and concrete compressive strength which are presumed effective variables. From experimental results, the equation of minimum steel ratio was newly proposed considered size effect.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.1
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• pp.47-57
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• 2024

Recently, in newly constructed apartment buildings, the exterior wall structures have been characterized by thinness, having various openings, and a significantly low reinforcement ratio. In this study, a nonlinear finite element analysis was performed to investigate the crack damage characteristics of the exterior wall structure. The limited analysis models for a 10-story exterior wall were constructed based on the prototype apartment building, and nonlinear static analysis (push-over analysis) was performed. Based on the finite element (FE) analysis model, the parametric study was conducted to investigate the effects of various design parameters on the strength and crack width of the exterior walls. As the parameters, the vertical reinforcement ratio and horizontal reinforcement ratio of the wall, as well as the uniformly distributed longitudinal reinforcement ratio and shear reinforcement ratio of the connection beam, were addressed. The analysis results showed that the strength and deformation capacity of the prototype exterior walls were limited by the failure of the connection beam prior to the flexural yielding of the walls. Thus, the increase of wall reinforcement limitedly affected the failure modes, peak strengths, and crack damages. On the other hand, when the reinforcement ratio of the connection beams was increased, the peak strength was increased due to the increase in the load-carrying capacity of the connection beams. Further, the crack damage index decreased as the reinforcement ratio of the connection beam increased. In particular, it was more effective to increase the uniformly distributed longitudinal reinforcement ratio in the connection beams to decrease the crack damage of the coupling beams, regardless of the type of the prototype exterior walls.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.769-774
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• 2000

The purpose of this study was to investigate the structural performance of reinforcement corrosion reinforced concrete beams strengthened with epoxy mortar system. Main test parameters are existence and the magnitude of the reinforcement corrosion and the reinforcing bar and the tensile reinforcement ratio of the specimens. eight beam specimens were tested to investigate the effectiveness of each test variables on maximum load capacity and failure mode. Test results showed that the ultimate moment of th specimens were higher tan the nominal moment and the flexural stiffness was increased about 2.5 times and the cracking moments occurred over 60% of the failure moment in comparison with same sized control beam. However, note that epoxy mortar may conduct member into brittle failure mode.

• Computers and Concrete
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• v.22 no.3
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• pp.305-317
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• 2018

Steel reinforced Engineered Cementitious Composite (ECC) components have been proposed for seismic structural applications, for example in coupling beams, infill panels, joints, columns, and flexural members. The development of strain in the steel reinforcement of cementitious components has been shown to vary based on both the steel reinforcement ratio and the applied deformation history. Strain in the steel reinforcement of reinforced ECC components is an important structural response metric because ultimate failure is often by fracture of the steel reinforcement. A recently proposed bond-slip model has been successfully calibrated to cyclically tested reinforced ECC beams wherein the deformation history contained monotonically increasing cycles. This paper reports simulations of two-dimensional finite element models of reinforced ECC beams to determine the appropriateness and significance of altering a phenomenological bond-slip model based on the applied deformation history. The numerical simulations with various values of post-peak bond-slip softening stiffness are compared to experimental results. Varying the post-peak bond-slip softening stiffness had little effect on the cracking patterns and hysteretic response of the reinforced ECC flexural models tested, which consisted of two different steel reinforcement ratios subjected to two different deformation histories. Varying the post-peak bond-slip softening stiffness did, however, affect the magnitude of strain and the length of reinforcing bar that strain-hardened. Overall, a numerical model with a constant bond-slip model represented well various responses in reinforced ECC beams with multiple steel reinforcement ratios subjected to different deformation histories.