• 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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• 2002.05a
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• pp.247-252
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• 2002

The evaluation equation of torsional moment for reinforced concrete members in ACI 318-99 ignores the contribution of concrete, T$_{c}$. Several research indicates that the torsional moment of concrete is in effect, specially for the members in which the longitudinal and transverse reinforcement content is small. This paper proposes an evaluation equation of torsional moment taking into account the contribution of concrete. According to the comparison with the 66 test results, the torsion equation in ACI code underestimated or overestimated the real torsional moment of reinforced concrete beams. On the other hand, the proposed torsional equation is shown to be in a good agreement with experimental results.s.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.22-27
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• 2004

This experimental investigation was conducted to examine the seismic performance of reinforced concrete bridge columns. The columns were subjected to a constant axial load and a cyclic horizontal load-inducing reversed bending moment. The variables studied in this research are the volumetric ratio of transverse reinforcement (ps = 0.96, 1.44 per cent) and axial load ratio (0.05, 0.1, 0.2 P/Po) and strength $(350kgf/cm^2,\;600kgf/cm^2)$. Test results show that bridge columns with 50 per cent higher amounts of transverse reinforcement than that required by seismic provisions of ACI 318-02 showed ductile behaviour. For bridge columns with axial load ratio(P/Po) less than 0.2, the ratio of Mmax over Mad, nominal moment capacity predicted by ACI 318-02 provisions, is consistently greater than 1 with approximately a 20 percent margin of safty.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.272-275
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• 2004

This study is to propose a modified equivalent frame method under lateral loading. ACI 318-02 allows the equivalent frame method to conduct slab analysis subjected to lateral loads. However, current method can not predict the behavior of the slabs particularly under lateral loading because the equivalent frame method in the ACI 318 has been developed against gravity loads. This study provides more precise model for the analysis of the flat plate slabs under lateral loading. The model reflect the force transfer mechanism of slabs, column and torsional member more accurately than the existing model. The accuracy of this model is verified by compared with finite element method analysis results.

• Journal of Chest Surgery
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• v.28 no.5
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• pp.443-446
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• 1995

The present study was designed to determine whether cyclosporine A inhibits Major Histocompatibility Complex Class II antigen[MHC II expression in the allograft rat heart myocardium. In this rat allograft study we also tried to elucidate whether CSA inhibits MHC II in a dose dependent way. Hearts were isolated from LBN rats weighing 200-250 grams and heterotopically transplantated into the abdomen of weight-matched ACI rats. The ACI rats were randomly assigned to one of the three experimental groups according to cyclosporine dosage: {1}control [no CSA , n=6 {2}CSA 5 mg/day , n=5 {3}CSA 10 mg/day, n=5. The transplanted hearts were harvested 5 days postoperatively and analyzed. MHC II expression was detected by indirect immunoperoxidase staining and quantified via computer image analysis system. The % positive area reading was obtained in each slide [50 areas per group and compared to other groups. Significant differences were noted between three groups [p<0.05 . We conclude that CSA inhibits MHC II in heterotopically transplanted allograft rat heart in a dose dependent way.

• Journal of the Korean Society of Safety
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• v.25 no.4
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• pp.48-60
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• 2010

The fire resistance performance of 2 RC slabs after exposure to the ISO-834 fire standard without loading has been experimentally investigated. A Comparison is made of the fire resistance performance between RC slabs without PP(polypropylene) fibers and RC slabs with PP fibers. From the fire test results, the presence of PP fibers in RC slabs can reduce spalling and enhance their fire resistance. Until now, the determination of fire resistance of reinforced concrete(RC) slabs has essentially been based on tabulated data. According to ACI 216 code and EUROCODE 2, the design of concrete structures is essentially based on tabulated data for appropriate concrete cover and various fire durations. From the comparison between fire test results and codes, current fire design provisions of codes such as the ACI 216 and the EUROCODE 2 are unconservative for estimating mechanical properties of RC slabs at elevated temperatures.

• Computers and Concrete
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• v.10 no.2
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• pp.149-171
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• 2012

The problem of a concrete cross section under flexural and axial loading is indeterminate due to the existence of more unknowns than equations. Among the infinite solutions, it is possible to find the optimum, which is that of minimum reinforcement that satisfies certain design constraints (section ductility, minimum reinforcement area, etc.). This article proposes the automation of the optimum reinforcement calculation under any combination of flexural and axial loading. The procedure has been implemented in a program code that is attached in the Appendix. Conventional-strength or high-strength concrete may be chosen, minimum reinforcement area may be considered (it being possible to choose between the standards ACI 318 or Eurocode 2), and the neutral axis depth may be constrained in order to guarantee a certain sectional ductility. Some numerical examples are presented, drawing comparisons between the results obtained by ACI 318, EC 2 and the conventional method.

• Journal of the Korea Concrete Institute
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• v.12 no.1
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• pp.53-60
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• 2000

The objective of this study is to investigate the flexural behavior of reinforced concrete columns confined by lateral ties. This test was carried on the twelve reinforced concrete columns subjected to lateral and constant axial loads. The main experimental variables are concrete strength, the configuration of lateral ties, and the amount of lateral ties. Test results indicated that the steel configuration in column sections plays an important role in column behavior, and a proper configuration of lateral ties can obtain more ductile by the reduction of the space of lateral ties. Also, this experiment show that the utlization of high-strength concrete in columns properly designed on ACI Code takes less ductile. Therefore, we can conclude that the design of high-strength concrete columns under high axial loads requires more lateral ties than ACI Code.

• Journal of the Korea Concrete Institute
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• v.12 no.1
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• pp.89-99
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• 2000

The objective of this study is to investigate the bond strength properties of antiwashout underwater concrete. The arrangement of bars (vertical bar, horizontal upper bar, horizontal lower bar), condition of casting and curing (fresh water, sea water), type of fine aggregate (river sand, blended sand(river sand : sea sand = 1:1), and proportioning strength of concrete (210, 240, 270, 300, 330kgf/$\textrm{cm}^2$)are chosen as the experimental parameters. The test results(ultimate bond stress) are compared with bond and development provisions of the ACI Building Code(ACI 318-89) and proposed equations from previous research(which was proposed by Orangun et. al). The experimental results show that ultimate bond stress of antiwashout underwater concrete which arranged bar on the horizontal lower, used the blend sand, and was cast and cured in the fresh water are higher that other conditions. The ultimate bond stress were increased in proportion to {{{{( SQRT {fcu }) }}3 2. From this study, rational analytic formula for the ultimate bond stress are to be from compressive strength of concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.26-29
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• 2006

A flat plate-column connection is susceptible to brittle punching shear failure, which may result in the necessity of shear reinforcement. In present study, experimental tests were performed to study the capacity of slab-column connections strengthened with lattice, stud rail, shear band and stirrup under gravity and cyclic lateral load. Among them, the capacity of the specimens with lattice are superior to the others due to the truss action of the lattice bars and dowel action of the longitudinal bars as well as the shear resistance of the web re-bar. On the other hand, the strengths of the specimens with stud rail, shear band and stirrup are lower than the estimated strength by the ACI, therefore design formulas of the ACI are needed to revise.