• Title/Summary/Keyword: 연성도 평가

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Influence of ductility of reinforcement on the plastic hinge formation (철근의 연성이 소성힌지 생성에 미치는 영향)

  • Park, Dae-Gyun;Cho, Jae-Yeol;Park, Sung-Hyun
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.97-100
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    • 2008
  • Subjected to seismic action causing large deformation of bridge columns, the plastic hinge region is commonly formed in the column end zone. The deformation capacity of a concrete column can be expressed by using plastic hinge length. The mechanical properties of high-strength reinforcing steel is different from that of normal-strength steel and the mechanical properties of steel will influence the plastic hinge formation. Therefore, in other to accurately predict the deformation of concrete column using high-strength steel, the plastic hinge length can be expressed as a function of the mechanical properties of steel such as the tensile to yield strength ratio and the strain at ultimate state. However, little research has been conducted into the effect of mechanical properties of steel on the plastic hinge length. It was difficult to measure the plastic hinge length from the test results. Therefore, the plastic hinge length of concrete columns was investigated from the curvature profile. A numerical approach was used to study the effect of various parameters on plastic hinge length. Based on the results of the numerical parametric study, a new expression for plastic hinge length was proposed.

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Numerical Evaluation of Boundary Effects in the Laminar Shear Box System (층 분할된 연성전단상자의 경계효과에 관한 수치해석적 분석)

  • Kim, Jin-Man;Ryu, Jeong-Ho
    • Journal of the Korean Geotechnical Society
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    • v.24 no.8
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    • pp.35-41
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    • 2008
  • Laminar-shear-boxes are widely used to simulate free-field seismic ground response by using a l-g shaking table or geo centrifuge in geotechnical earthquake engineering. This study numerically modeled and compared the ground responses in the free field, rigid box, and laminar shear box by using a 3-D FEM program. It is found from the numerical simulations that the laminar shear box can simulate the free field ground movement more precisely than the rigid box. However, the laminar shear box underestimated the surface acceleration of the free field ground. It also showed low-frequency characteristics probably because the stiffness and inertia effect of surrounding ground are neglected.

Seismic Performance of Column-Footing Connection of Modular Pier using CFT (CFT를 이용한 모듈러 교각 기둥-기초 연결부의 내진성능)

  • Kim, Ji Young;Kim, Ki Doo;Ma, Hyang Wook;Chung, Chul-Hun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.1
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    • pp.73-85
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    • 2014
  • The CFT (Concrete Filled steel Tubes) column-footing connection is cast-in-place embedded type which provides simple construction procedure, low cost, and superior structural performance. In this study, CFT column-footing connection of modular pier is proposed and structural performance is evaluated by experimental tests. To evaluate structural performance of the CFT column-footing connection, a series of experimental tests were performed for the 4 specimens with different embedded depth. As a result of the quasi-static test, the specimen with 0.6D (0.6 times the outside diameter of steel tube) embedded depth showed relatively low ductility than other specimens with larger embedded depth due to cone failure of base concrete occurred during the lower loading step. On the contrary, cone failure of the base concrete was not observed in the specimens with larger embedded depth than 0.9D, but typical flexural failure in lower part of CFT column was observed. With the analyses of force-displacement curve, displacement ductility, and energy dissipation capacity, it is concluded that the rational range of embedded depth of the CFT column-footing connection is from 0.9D to 1.2D in view of good seismic performance.

Soft Information and Government Loan Approval (연성정보와 정책자금 대출결정 요인 분석)

  • Yoo, Shi-Yong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.10 no.12
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    • pp.3768-3774
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    • 2009
  • This paper explored how soft information and hard information were used when SBC(Small Business Corporation, Korea) reviewed government loan applications. The data set is made up of financial and non-financial data of small-business firms since 2004. A non-financial data set is considered as soft information. Relative importance of three kinds information such as credit information, soft information, financial information is compared with each other by using the logit model. As a result, credit information is most critical to the loan approval, and then soft information follows, lastly financial information has the smallest effect on the loan approval. This is because the credit information is made up of the non-linear combination of soft information and financial information. When the relative importance of soft information and financial information is considered, soft information is relatively more critical to the loan approval then financial information. This is because financial ratios provided by small-business firms are not reliable enough.

Predictions of Curvature Ductility Factor of Reinforced Concrete Beam Sections Used High Strength Concrete and Steel (고강도 재료를 사용한 철근콘크리트 보 단면의 곡률연성지수 예측)

  • Lee, Hyung Joon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.33 no.2
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    • pp.483-493
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    • 2013
  • The high strength materials have been more widely used in a large reinforced concrete structures. It is known that the use of high strength material in RC structures give the benefits of the mechanical and durable properties, but the ductility decreases with an increase in the strength of the materials. In the design of a reinforced concrete beam, both the flexural strength and ductility need to be considered. So, it is necessary to assess accurately the ductility of the beam with high strength materials in order to ensure the ductility requirement in design. In this study, the effects of the material strength on the flexural behavior and curvature ductility factor of reinforcement concrete beam sections with various reinforcement conditions have been evaluated and a newly prediction formula for curvature ductility factor of RC beam has been developed considering the stress of compression reinforcement at ultimate state. The proposed predictions for the curvature ductility factor which is applicable to both singly and doubly reinforced concrete beam are verified by comparisons with other prediction formulas and the proposed formula offers fairly accurate within 9% error and consistent predictions for curvature ductility factor of reinforced concrete beam.