• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2115_2116
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• 2009

철탑기초의 콘크리트 압축강도가 Core시험결과 설계기준강도에 미달된 철탑기초에 대한 보강방안은 콘크리트의 강도가 부족함으로써 발생되는 콘크리트 기초 본체에 대한 문제로서 콘크리트의 허용 펀칭전단응력의 감소로 발생되는 기초 상판부의 두께 부족 문제와 앵카재의 소요길이 부족 등으로 압축시킬 수 있다. 이에 대한 대책으로써 펀칭전단에 의한 기초 상판부 두께가 부족한 문제와 앵커재 길이 부족 문제에 대한 기초강도 보강방안을 분석하고자 한다.

• Journal of Korean Association for Spatial Structures
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• v.6 no.2 s.20
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• pp.53-60
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• 2006

The shear failure modes of reinforced concrete members using high-strength materials (high-strength concrete and high-strength steel) are different to those of reinforced concrete members using normal-strength materials. The reinforced concrete members using high-strength materials are inclined to fail due to concrete crushing before the shear reinforcing bar reaches its yield strength. This paper presents an evaluation equation to calculate the maximum shear reinforcement ratio based on the material stresses and strains when the reinforced concrete members fail in shear. The maximum shear reinforcement ratio calculated by the proposed equation increases as the compressive strength of concrete increases. Test results of 97 reinforced concrete members reported in the technical literatures are used to check the validity of the proposed equation. The comparison between the test results and the ratio calculated using the proposed equation indicated that the shear failure modes depended on the interaction between the amount of shear reinforcement and the compressive strength of concrete.

• Journal of the Korea Concrete Institute
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• v.23 no.2
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• pp.185-193
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• 2011

In the present study, a unified shear design method was developed to evaluate the shear strength of concrete beams with and without FRP shear reinforcement. The contributions of FRP and concrete on shear strength were defined separately. By comparing the current design method calculated results with the existing test results, it was found that Triantafillou model shows a reliable prediction of FRP effective strain and FRP shear strength contributions. The concrete shear strength contribution was defined by the strain-based shear strength model developed in the previous study. The shear strength of concrete compression zone was evaluated based on the material failure criteria of the concrete subjected to the compressive normal and shear stresses. The proposed strength model was verified by comparing its prediction results to prior test results. The comparisons showed that the proposed method accurately predicts the strengths of the test specimens for both FRP shear reinforced and unreinforced concrete beams.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.6
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• pp.72-81
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• 2014

This paper reports the test results of reinforced concrete exterior beam-column joints with high-strength concrete. The main parameters of eight specimens were joint failure modes, the compressive strength of concrete, and the head shapes of steel bars. All specimens were designed according to ACI 352R-02 design recommendations. Two types of failure modes were considered; J-failure and BJ-failure. The longitudinal steel bars were anchored by 90 degree standard hooks or headed reinforcement. Experimental results indicated that the current ACI design recommendation limited by the compressive strength of concrete somewhat underestimated the strength of beam-column joints with high-strength concrete. In the specimens showed joint shear failure, the strength of beam-column joints with headed bars was approximately 10 percent higher than that of joints with 90 degree standard hooks.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.335-336
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• 2009

In this study, the properties of lightweight concrete which is beneficial to cost and technique by reducing self weight of structure member was carried out basic research. The unit weight, compressive strength, splitting tensile strength test have been conducted with producting plain concrete, lightweight aggregate concrete type I and type II to check the basic properties. The compressive strength of 21MPa was obtained easily by using lightweight aggregate concrete and addition of silica fume increase the compressive strength slightly. To use lightweight aggregate concrete for civil engineering structure, systematic and rigorous studies are necessary.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.4
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• pp.159-169
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• 2003

In the ACI Code, the empirical equations governing deep beam design are based on low-strength concrete specimens with $f_{ck}$ in the range of 14 to 40MPa. As high-strength concrete(HSC) is becoming more and more popular, it is timely to evaluate the application of HSC deep beam. For the shear strength prediction of HSC deep beams, this paper proposed Softened Strut-and-Tie Model(SSTM) considered HSC and bending moment effect. The shear strength predictions of the proposed model, the Appendix A Strut-and-Tie Model of ACI 318-02, and Eq. of ACI 318-99 11.8 are compared with the experimental test results of 4 deep beams and the collected experimental data of 74 HSC deep beams, compressive strength in the range of 49~78MPa. The proposed SSTM performance consistently reproduced 74 HSC deep beam measured shear strength with reasonable accuracy for a wide range of concrete strength, shear span-depth ratio, and ratio of horizontal and vertical reinforcement.

• Journal of Korean Society of Steel Construction
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• v.26 no.5
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• pp.473-483
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• 2014

According to the Korean Building Code (KBC), the validity of the application of 800MPa grade steel(HSA800) to composite column should be verified by experimental or analytical method. Thus, stub column tests for encased and filled composite members with HSA800 steel were conducted, and axial strength and the validity of design compressive strength equations in KBC were evaluated. The test results show that the equation of the compressive strength of encased composite column member in KBC should be modified in order to use HSA800 steel without any reduction of specified minimum yield strength. For this purpose, it is suggested that the interval of hoop should be narrowed and the effective concrete area should be used. The equation of the compressive strength of filled composite column member in KBC is applicable to filled composite column with HSA800 steel without any modification.

• Journal of the Korea Concrete Institute
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• v.25 no.2
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• pp.225-232
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• 2013

The recent worldwide trend in construction industry tends to put emphasis on the performance based design which focuses on the suggestion of the performance of final products rather than method and procedures. A proper model should be employed when predicting the concrete strength, which reflects the material age, in order to verify the function of concrete structures and their materials. Accordingly, this paper proposes the concrete strength development constant (${\alpha}_{sc}$) reflecting the characteristics of domestic materials and then evaluates its suitability.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.3
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• pp.261-266
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• 2017

In this study, to determine the shear properties, experiments on the shear behavior of plain concrete with the high volume fly ash cement by double shear test were performed. Test parameters are fly ash content and concrete compressive strength. Experimental results show the tendency that the shear strength similarly increases with an increase in the compressive strength as is generally known. The concrete shear strength formula proposed in the concrete structural design code of KCI shows a similar tendency to the experimental results, and It is expected that the shear strength of the high volume fly ash cement concrete can be applied with the formula given in the concrete structural design code of KCI. When considering the fly ash content ratio, the shear strength of high volume fly ash cement concrete according to fly ash conctent ratio shows as having a far greater correlation than if it is not considered to fly ash content ratio. So, even though existing code can be appliable for non consideration of the fly ash content ratio, we proposed a formula that is much more relevant than that of concrete structural design code of KCI.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.143-144
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• 2010

As KCI under U.S.D is impossible to calculate all sections compared P-M Interaction Curve of the circular concrete column under EC2 of limit state design and KCI. Result of the construction, P-M Interaction Curve according to design for standard is about the same. If a covering depth rased, EC2 is better safety than KCI.