• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.331-338
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• 1995

Results of an experimental of the shear and flexures strength of doubly reinforced concrete beams were summarized. A total of 24 beams was tested; 4 without web reinforcement and 20 with web reinforcement in the form of vertical stirrups. Main variables were compressive strength of concrete which was 26.88MPa and 63.4MPa, spacing of stirrups which was no-stirrups, 200, 150, 120, 100 and 90mm. Tests results were compared with stength predicted using the equations of ACI 318-89. The shear reinforcement ratio of the beams, which failed simultaneously under both flexures and shear, were 0.66pvmax for low strength concrete beams and 0.56pvmax for high strength concrete beams, respectively. Thus, ACI equations for shear reinforcement were very conservative.

• Proceedings of the Korea Concrete Institute Conference
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• 1989.10a
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• pp.77-82
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• 1989

In this paper an experimental approach of the relocation plastic hinging zones of nine reinforced concrete exterior beam-column subassemblages under cyclic loads was tried. The main parameters of the testing program were location of the plastic hinge, difference of the special reinforcement, inclined or intermediate layers of longitudinal reinforcement, applied maximum shear stress. The conclusions presented herein are based on the limited texts conducted. Inclined or intermediate layers of longitudinal reinforcement and extra top and bottom steel in the beam over a specific legnth can be used to move the beam plastic hinging zone away from the column face. But, for the use of intermediate layers of longitudinal reinforcement, sheat reinforcement detail need further investigation.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.53-56
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• 2005

This paper investigates the effect of ductile deformation behavior of high performance hybrid fiber-reinforced cement composites (HPHFRCCs) on the shear behavior of coupling beams to lateral load reversals. The matrix ductility and the reinforcement layout were the main variables of the tests. Three short coupling beams with two different reinforcement arrangements and matrixes were tested. They were subjected to cyclic loading by a suitable experimental setup. All specimens were characterized by a shear span-depth ratio of 1.0. The reinforcement layouts consisted of a classical scheme and diagonal scheme without confining ties. The effects of matrix ductility on deflections, strains, crack widths, crack patterns, failure modes, and ultimate shear load of coupling beams have been examined. The combination of a ductile cementitious matrix and steel reinforcement is found to result in improved energy dissipation capacity, simplification of reinforcement details, and damage-tolerant inelastic deformation behavior. Test results showed that the HPFRCC coupling beams behaved better than normal reinforced concrete control beams. These results were produced by HPHFRCC's tensile deformation capacity, damage tolerance and tensile strength.

• Structural Engineering and Mechanics
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• v.40 no.6
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• pp.867-883
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• 2011

Six reinforced concrete beam-column joint specimens were constructed and tested under reverse cyclic loading to failure. The six specimens were divided into three groups, each group representing a different joint design. The main objectives of this study are to investigate the response of joints with three different design, reinforcement detailing and beam strengths, and to evaluate and compare the responses of beam-column joints reinforced with traditional steel rebar and a recently proposed steel reinforcement called prefabricated cage system (PCS). Each of the three test specimen designs included equivalent amount of steel reinforcement and had virtually identical details. The results of the research show that the PCS reinforced joints had a slightly higher strength and significantly larger deformation capacity than the equivalent rebar reinforced joints.

• Journal of the Korean Society of Hazard Mitigation
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• v.2 no.1 s.4
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• pp.119-126
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• 2002

This paper presents the appropriateness for using high strength reinforcement according to the use of high strength concrete. Nine flexural tests were conducted on full-scale beam specimens according to the concrete strength, reinforcement strength and reinforcement ratio as main variable. The structural behavior was analyzed due to the flexural strength, stress-strain curve, deflections at yielding and fracture point, crack appearance and ductility factor. The member with high-strength reinforcements showed large deflection at yielding point and this was analyzed as a main cause to decrease the ductility factor. Structural behavior after yielding point, however, showed similarity to behavior of members with normal strength reinforcements of same stiffness. It was found that in the case of using reinforcements of $5500kgf/cm^2$ strength, the combination with concrete of $800kgf/cm^2$ strength demonstrated the great appropriateness which can increase the flexural capacity without any reduction of maximum reinforcement ratio.

• International Journal of Automotive Technology
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• v.6 no.6
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• pp.643-655
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• 2005

The frontal crash optimization of S-shaped closed-hat section member using the homogenization method, design of experiment (DOE) and response surface method (RSM) was studied. The optimization to effectively absorb more crash energy was studied to introduce the reinforcement design. The main focus of design was to decide the optimum size and thickness of reinforcement. In this study, the location of reinforcement was decided by homogenization method. Also, the effective size and thickness of reinforcements was studied by design of experiments and response surface method. The effects of various impact velocity for reinforcement design were researched. The high impact velocity reinforcement design showed to absorb the more crash energy than low velocities design. The effect of size and thickness of reinforcement was studied and the sensitivity of size and thickness was different according to base thickness of model. The optimum size and thickness of the reinforcement has shown a direct proportion to the thickness of base model. Also, the thicker the base model was, the effect of optimization using reinforcement was the bigger. The trend curve for effective size and thickness of reinforcement using response surface method was obtained. The predicted size and thickness of reinforcement by RSM were compared with results of DOE. The results of a specific dynamic mean crushing loads for the predicted design by RSM were shown the small difference with the predicted results by RSM and DOE. These trend curves can be used as a basic guideline to find the optimum reinforcement design for S-shaped member.

• KIEAE Journal
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• v.8 no.5
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• pp.61-68
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• 2008

For the recycling of the resources and the preservation of the environment, this study's purpose is to measure flexural behavior of the reinforced concrete beams with the major variables like concrete strength, replacement ratio of the recycled aggregate and the waste foundry sand and the tension reinforcement ratio and to present the data of the recycled aggregate used for the structure design. The experiment on the flexural behavior resulted in the followings. The ultimate strength of recycled R/C beam was manipulated proportionate to the tension reinforcement ratio, however the strength instantly decreased after passing the ultimate load due to the destroyed concrete of the compression side. The deflection at the maximum load varied from the tension reinforcement ratio by 5.5 times. The test specimen with the tension reinforcement ratio less than $0.5{\rho}b$ showed constant curve without change in the load from the yield to the ultimate load in contrast to the distinctive plastic region where the displacement was rising. Although the strain of main tension steel with the reinforcement ratio indicate different, the design of recycled concrete member can be applied for current design code for reinforced concrete structure as the ratio of tension reinforcement district the under the reinforcement ration in a balanced strain condition.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.6
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• pp.1-8
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• 2012

This study estimates the performance of confined concrete according to the configuration of transverse steel bars. The main test variables were the yield strength of spiral reinforcement and configuration of transverse reinforcement. A total of 27 specimens with rectangular cross section were cast and tested under monotonic concentric compression. R-type specimens with rectangular spirals, C-type specimens with circular spirals and O-type specimens with combined shape of rectangular and octagon were designed in this study. From experimental results, it is concluded that the proposed configuration of transverse reinforcement can provided improved ductility to the confined concrete compared to rectangular spiral reinforcement.

• Journal of the Korean Geotechnical Society
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• v.16 no.6
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• pp.127-139
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• 2000

In the study, an expert system was developed to predict the safety of tunnel and select proper tunnel reinforcement system using fuzzy quantification theory and fuzzy inference rule based on tunnel information database, For this development, many tunnelling sites were investigated and the applied countermeasures were studied after building tunnel database. There will be benefit for the deciding tunnel reinforcement method in the case of poor ground condition. The expert system developed in the study has two main parts, pre-module and post-module. Pre-module is used to decide input items of tunnel information based on the tunnel face mapping information which can be easily obtained in in-situ site. Then, using fuzzy quantification theory II, fuzzy membership function is composed and tunnel safety level is inferred through this membership function. Post-module is used to infer the applicability of each reinforcement methods according to the face level. The result of the predicted reinforcement system level was similar to measured ones. In-situ data were obtained in three tunnel sites including subway tunnel under Han River. Therefore, this system will be helpful to make the mose of in-situ data available and suggest proper applicability of tunnel reinforcement system to development more resonable tunnel support method without dependance of some experienced experts opinions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.1
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• pp.259-269
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• 2005

This paper describes the application of genetic algorithm for the discrete optimum design of reinforced concrete continuous beams. The objective is to minimize the total cost of reinforced concrete beams including the costs of concrete, form work, main reinforcement and stirrup. The flexural and shear strength, deflection, crack, spacing of reinforcement, concrete cover, upper-lower bounds on main reinforcement, beam width-depth ratio and anchorage for main reinforcement are considered as the constraints. The width and effective depth of beam and steel area are taken as design variables, and those are selected among the discrete design space which is composed with dimensions and steel area being used from in practice. Optimum result obtained from GA is compared with other literature to verify the validity of GA. To show the applicability and efficiency of GA, it is applied to three and five span reinforced concrete beams satisfying with the Korean standard specifications.