• Structural Engineering and Mechanics
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• 제56권2호
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• pp.275-291
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• 2015

Adherence between reinforcement and the surrounding concrete is usually ignored in finite element analysis (FEA) of reinforced concrete (RC) members. However, load transition between the reinforcement and surrounding concrete effects RC members' behavior a great deal. In this study, the effects of bond-slip on the FEA of RC members are examined. In the analyses, three types of bond-slip modeling methods (perfect bond, contact elements and spring elements) and three types of reinforcement modeling methods (smeared, one dimensional line and three dimensional solid elements) were used. Bond-slip behavior between the reinforcement and surrounding concrete was simulated with cohesive zone materials (CZM) for the first time. The bond-slip relationship was identified experimentally using a beam bending test as suggested by RILEM. The results obtained from FEA were compared with the results of four RC beams that were tested experimentally. Results showed that, in FE analyses, because of the perfect bond occurrence between the reinforcement and surrounding concrete, unrealistic strains occurred in the longitudinal reinforcement. This situation greatly affected the load deflection relationship because the longitudinal reinforcements dominated the failure mode. In addition to the spring elements, the combination of a bonded contact option with CZM also gave closer results to the experimental models. However, modeling of the bond-slip relationship with a contact element was quite difficult and time consuming. Therefore bond-slip modeling is more suitable with spring elements.

• 한국지진공학회논문집
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• 제26권4호
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• pp.165-172
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• 2022

This study is conducted to verify the seismic reinforcement effects of internally inserted buckling-restrained braces supported laterally by buckling-restrained rings for the seismic reinforcement of existing reinforced concrete buildings with non-seismic details. First, to evaluate the performance of KDS, the hysteretic characteristics of buckling-restrained braces are verified, and it is discovered that they satisfy the conformance criteria of the displacement-dependent damping device. Three full-scale, two-story reinforced concrete framework specimens are prepared to verify the seismic reinforcement effects, and the proposed buckling-restrained braces are bolstered with single diagonal and V-shaped braces to be compared with non-reinforced specimens. By performing a comparison with non-reinforced specimens that present intensive shear cracks at the bottom of first-floor columns, it is revealed that the maximum load and energy dissipation of specimens reinforced with the proposed buckling restrained braces, in which the structural damage extends evenly throughout the system, are approximately 4 and 6.2 times higher, respectively, which proves the effectiveness of the proposed seismic reinforcement method.

• 동서간호학연구지
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• 제10권1호
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• pp.53-60
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• 2004

The purpose of this study was to examine the effects of the short term education and reinforcement program to health promotion in women in mid-life. This study has been done between February and April, 2004 and the subjects of the study were 26 women in mid-life. The treatment intervention was applied during total 8 weeks as 5 days for the short term education and 7 weeks for reinforcement with 1 time per a week. The short term education included health education for menopause, effect of exercise, healthy diet, management of stress and management of chronic illness and stretching exercise and recreation. The collected data were processed using the SPSS Win(12.0) program and analyzed using Wilcoxon Signed Ranks Test. The result of this study are as follows : 1. The short term education and reinforcement program significantly effected on the total cholesterol, HDL-cholesterol, triglyceride. 2. The short term education and reinforcement program significantly effected on the anxiety, but not depression. 3. The short term education and reinforcement program non significantly effected on the sleep disturbance and self-efficacy of exercise. 4. The short term education and reinforcement program significantly effected on the practice of healthy life. In conclusion, the short term education and reinforcement program effected on the physical health index, anxiety and practice of healthy life.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.441-444
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• 1999

The crack width of concrete structures subjected to shrinkage depend on a great number of parameters whose effects are restrain condition, the number and spacing of crack and the amounts of reinforcements. Through suitable reinforcement it is possible to make the individual cracks exceedigly small. This paper is to present the amount of reasonable reinforcement for crack control through a rational analysis of forces occuring in significantly restrained concrete structures due to the shrinkage. Also the analysis results from this paper are compared with the provisions for shrinkage and temperture reinforcement in the KCI concrete strucural design code.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 봄 학술발표회 논문집
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• pp.121-128
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• 1999

Recently, research of reinforcement mechanism in a sense of soil mechanics has been under way by many researchers with developing various kinds of geoteutiles. But it must be consider that reinforcement effect largely depends on used geotextile even if it is used on same in-site condition. As a matter of fact it is not necessarily that reinforcement effect appears in all the case of reinforced soil construction. It means that appropriate geotextile coincided with the intention has to be selected and adequate examination is needed. In this study, reinforcement effect with various kinds of geotextiles are compared through a series of direct shear tests. Based on the test results, shear strength characteristics and reinforced effects are investigated quantitatively and qualitatively considering the confining stress, reinforcement characteristics and number of reinforcement.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.256-259
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• 2004

The objective of this experimental study is to understand the effects of horizontal and vertical shear reinforcement on the shear strength of concrete deep beams. Main variables were the horizontal shear reinforcement ratio $(P_{sh})$, vertical shear reinforcement ratio$(P_{sv})$ and shear span-to-overall depth ratio(a/h). Test results revealed that the effectiveness of shear resistance of shear reinforcement was greatly related to the a/h. For the beams with $a/h\geq1.0$, the vertical shear reinforcement was more effective than horizontal shear reinforcement.

• 콘크리트학회논문집
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• 제11권5호
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• pp.61-68
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• 1999

Confinement is one of the major concepts for bond of reinforcing steel to concrete. Cover distance, and lateral reinforcement are the key factors for current provisions for development and splices of reinforcement. However, the current provisions still being complicated to calculate major variables need to be developed in the process of design. In this study, an experimental work was performed to examine the behavior of bond using beam end specimens. The test results and previous available data are analyzed to isolate the effects of confinement on bond strength. From this reevaluation, new provisions for development and splice of reinforcement are proposed. The provisions also propose some limits for confinement index. The new provisions will help engineers to decide easily the simple but conservative way for manual calculations or the exact approach for computerized design.

• Structural Engineering and Mechanics
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• 제23권4호
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• pp.369-386
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• 2006

The influence of reinforcement buckling on the flexural response of reinforced concrete members is studied. The stress-strain response of compression reinforcement is determined computationally using a large-strain finite element model for bars of varied diameter, length, and initial eccentricity, and a mathematical expression is fitted to the simulation results. This relationship is used to represent the response of bars in compression in a moment-curvature analysis of a reinforced concrete cross section. The compression bar may carry more or less force than a tension bar at a corresponding strain, depending on the relative influence of Poisson effects and bar slenderness. Several cross-section analyses indicate that, for the distances between stirrups prescribed in modern concrete codes, the influence of inelastic buckling of the longitudinal reinforcement on the monotonic moment capacity is very small and can be neglected in many circumstances.

• Structural Engineering and Mechanics
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• 제67권1호
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• pp.93-104
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• 2018

The seismic behavior of reinforced concrete (RC) short columns with limited transverse reinforcement is investigated in this paper through an experimental program. The experimental program consists of four small-scale RC columns with an aspect ratio of 1.7, which are tested to the axial failure stage. The cracking patterns, hysteretic responses, strains in reinforcing bars, displacement decomposition and cumulative energy dissipation of the tested specimens are reported in detail in the paper. The effects of column axial load are investigated to determine how this variable might influence the performance of the short columns with limited transverse reinforcement. Brittle shear failure was observed in all tested specimens. Beneficial and detrimental effects on the shear strength and drift ratio at axial failure of the test specimens due to the column axial load are found in the experimental program, respectively.

• 한국구조물진단유지관리공학회 논문집
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• 제2권3호
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• pp.188-193
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• 1998

An experimental study was performed on the pull-out behavior of 90-deg standard hooks from exterior beam-column connections. The effects of lateral confinement and fiber reinforcement of joint area were investigated. It was concluded ; (1) Substitution of the transverse column (confining) reinforcement with steel fibers at the joint region effectively reduces the extent of cracking in exterior joints caused by pull-out of hooked bars; and (2) The strength and ductility of hooked bars under pull-out forces are positively influenced by substituting the conventional confining reinforcement of exterior joints with steel fibers. Application of steel fibers to exterior joints seems to be an effective technique for improving the anchorage conditions of hooked bars, and also for reducing the congestion of reinforcement in exterior beam-column connections.