• Title, Summary, Keyword: 연성도

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Study on Seismic Performance of RC Column with Super-Flexibility Membrane (고연성재 보강 철근콘크리트 기둥의 내진성능 연구)

  • Lee, Weon-Cheol;Yhim, Sung-Soon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.5
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    • pp.1-12
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    • 2013
  • This study presents the evaluations of seismic performance and displacement ductility for two types of RC columns: existing RC column without SFM (Super Flexibility Membrane) and CSF (RC columns strengthened with SFM). After they are analyzed by the experiment as well as FEM, crack patterns and load-displacement curve of CSF by the former are shown to similar to those of CSF by the latter. The flexural cracks are dominant in CSF, whereas shear cracks in CNF (existing RC column without SFM). Displacement ductility of CSF is shown significantly to increase as well as ultimate displacement, compared to those of CNF. Therefore CSF can be replaced to CNF in order to increase the seismic performance and displacement ductility.

Disk Scheduling Scheme for Soft Real-Time Service (연성 실시간 서비스를 위한 디스크 스케줄링 기법)

  • 이용수;이승원;김정원;정기동
    • Proceedings of the Korea Multimedia Society Conference
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    • pp.349-352
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    • 2000
  • 본 연구에서는 연성 실시간 태스크 즉 비디오, 오디오와 같은 태스크의 실시간 적인 특성을 만족시키기 위하여 현재 각광 받고 있는 리눅스 커널을 사용하여 연성 실시간 커널을 개발하고자 한다. 리눅스 파일시스템의 디스크 스케줄링 은 오디오와 비디오와같은 연성 실시간 태스크의 실시간 요건을 고려하지 않았다. 본 연구에서는 우선 주기 당 일정 대역폭을 요구하는 멀티미디어 서비스를 지원하기 위해 디스크 대역폭 예약이 가능한 디스크 스케줄링 기법을 제시하여 태스크간 공정한 디스크 서비스를 제공한다.

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Evaluation of Flexural Ductility of Negative Moment Region of I-Girder with High Strength Steel (고강도 강재 적용 I-거더의 부모멘트부 휨연성 평가)

  • Joo, Hyunsung;Moon, Jiho;Choi, Byung-Ho;Lee, Hak-Eun
    • Journal of The Korean Society of Civil Engineers
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    • v.30 no.6A
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    • pp.513-523
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    • 2010
  • For continuous I-girder bridges, a large negative bending moment is generated near pier region so that plastic hinge is first formed at this point. Then, the bending moment is redistributed when the I-girder has enough flexural ductility (or rotational capacity). However, for I-girder with high strength steel, it is known that the flexural ductility is considerably decreased by increasing the yield strength of material. Thus, it is necessary to conduct a study for guaranteeing proper flexural ductility of I-girder with high-strength steel. In this study, the evaluation of flexural ductility of negative moment region of I-girder with high strength steel where yield stress of steel is 680 MPa is presented based on the results of finite element analysis and experiment. From the results, it is found that the flexural ductility of the I-girder is significantly reduced due to the increase of elastic deformation and the decrease of plastic deformation ability of the material when the yield strength increases. In this study, the method to improve the flexural ductility of I-girder with high strength steel is proposed by an unequal installation of cross beam and an optimal position of cross beam is also suggested. Finally, the effects of the unequal installation of cross beam on the flexural ductility are discussed based on the experimental results.

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
    • Journal of The Korean Society of Civil Engineers
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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.

Coupled Load Analysis Using MSC/Nastran Superelement (MSC/Nastran Superelement를 이용한 연성하중해석)

  • Kim, Gyeong-Won;Kim, Jin-Hui;Lee, Ju-Hun;Kim, Seon-Won
    • Aerospace Engineering and Technology
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    • v.5 no.2
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    • pp.60-66
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    • 2006
  • This paper is a study on the coupled load analysis using MSC/Nastran superelement method. After selecting the hunch vehicle, coupled load analysis is performed. From the results of coupled load analysis the loads and displacements on the major parts of satellite structure are calculated Based on the loads and displacements, the safety of satellite structure is judged. Coupled load analysis has been executed using MSC/Nastran DMAP code so far. Because DMAP code was very complicated and long in 1ength it was difficult to analyze and modify the DMAP code. To solve out these problems, coupled load analysis was executed using MSC/Nastran 2005 superelemnt method. At first, satellite FE-model was converted to the Craig-Bampton model using MSC/Nastran 2005 superelement method and verified Finally, coupled load analysis was performed using satellite Craig-Bampton model and launch vehicle FE-model and verified.

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Seismic Characteristics of Hollow Rectangular Sectional Piers with Reduced Lateral Reinforcements (횡방향철근이 감소된 중공사각단면 교각의 내진거동 특성)

  • Sun, Chang-Ho;Kim, Ick-Hyun
    • Journal of the Earthquake Engineering Society of Korea
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    • v.13 no.3
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    • pp.51-65
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    • 2009
  • The seismic design concept of RC bridges is to attain the proper ductility of piers, yielding a ductile failure mechanism. Therefore, seismic design force for moment is determined by introducing a response modification factor (R), and lateral reinforcements to confine core concrete are specified in the current design code. However, these design provisions have irrationality, which results in excessive amounts of lateral reinforcements for columns in Korea, which are generally designed with large sections. To improve on these provisions, a new design method based on seismic performance has been proposed. To apply this to hollow sectional columns, however, further investigations and improvements must be performed, due to the different seismic behaviors and confinement effects. In this study, hollow sectional columns with different lap-splice of longitudinal bars and lateral reinforcements have been tested. Seismic characteristics and performance were investigated quantitatively. These research results can be used to derive a performance-based design for hollow sectional columns.

Pseudo-Ductile Hybrid FRP Sheet for Strengthening Reinforced Concrete Beams (유사연성 하이브리드 FRP 시트를 이용한 RC 보의 휨 보강)

  • Ha, Sang-Su;Choi, Dong-Uk;Lee, Chin-Yong;Kim, Kil-Hee
    • Journal of the Korea Concrete Institute
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    • v.20 no.2
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    • pp.239-247
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    • 2008
  • Use of both carbon fiber (CF) and glass fiber (GF) at the same time to strengthen existing flexural members was exploited. Using a proper volumetric GF / CF ratio, the CF can rupture first followed by subsequent rupture of GF at higher stress and strain showing a pseudo-ductile behavior. A theoretical study indicated that the ratio is 4.62 : 1 and higher where the pseudoductile effect can be shown. Flexural tests of plain concrete beams strengthened using fibers were first carried out. Hybrid FRP sheet using 8.8 : 1 ratio was then fabricated and the sheet was used to strengthen reinforced concrete beams. The RC beams strengthened using 1-ply and 2-ply hybrid sheets both revealed increased strength over a non-strengthened beam and ductile flexural behavior. A comparable beam strengthened using CF also showed increased strength but with limited ductility.

Application of Soft OR to Strategy Formation: Perspectives and Applicability (전략수립과 연성운용연구 : 동향 및 적용가능성)

  • Kim, Do-Hyeon
    • Asia-Pacific Journal of Business Venturing and Entrepreneurship
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    • v.3 no.3
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    • pp.1-15
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    • 2008
  • The paper discusses application of soft OR methodologies, which have been developed for last decades centered in European OR communities, to strategy formation process. It is shown that there is strong similarity in understanding of strategy formation between descriptive school of strategy and the research trend of soft OR. The focus and philosophical background of cognitive school of strategy, in particular, share much in common with soft OR school. The analysis and overview of several soft OR methodologies are introduced. It is also proposed that SODA can be utilized more directly to the strategy formation process. However, it is also noted in this paper that the epistemological issues should be considered and resolved for fluent investigation of soft OR methodologies in relation with existing rich strategic research works, for soft OR adopts interpretative research methods while strategy research generally lies on positivistic approaches.

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Shear Reinforcement for Flat Plate-Column Connections Using Lattice Bars (래티스 철근을 이용한 무량판-기둥 접합부의 전단보강)

  • Ahn Kyung-Soo;Park Hong-Gun
    • Journal of the Korea Concrete Institute
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    • v.17 no.2
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    • pp.191-200
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    • 2005
  • Flat plate-column connections are susceptible to brittle punching shear failure, which may result in collapse of the overall structure. In the present study, a new shear reinforcement for the plate-column connection, the lattice shear reinforcement was developed. Experimental study for the lattice shear reinforcement was performed. Shear strength and ductility of the specimens reinforced with the lattice bars were compared with those of unreinforced specimens. The test results showed that the strength and ductility of the specimens with the lattice shear reinforcement were improved by 1.37 and 9.16 times those of the unreinforced specimens, respectively. These results indicates that the lattice shear reinforcement is superior in ductility to the shear stud-rail which is popular in U.S. Based on the test results, the design method for the lattice shear reinforcement was developed.