• Title/Summary/Keyword: 준-정적 해석

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Parametric Study on the P-M Interaction Diagram of Hollow Prestressed Concrete Bridge Columns (중공 프리스트레스트 콘크리트 교각의 P-M 상관도 매개변수 분석)

  • Kim, Tae-Hoon
    • Journal of the Earthquake Engineering Society of Korea
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    • v.15 no.6
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    • pp.1-10
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    • 2011
  • This study presents the results of parametric studies of the P-M interaction diagram of hollow prestressed concrete bridge columns. Among the numerous parameters, this study concentrates on concrete compressive strength, prestressing steel reinforcement ratio, effective prestress, the Ds/Do ratio, and the Di/Do ratio. The strength and ductility of hollow prestressed concrete bridge columns were evaluated through quasistatic tests. The P-M interaction diagrams from the codes were different from that of the results, which were in good agreement with AASHTO-LRFD. Nondimensionalized P-M interaction diagrams were developed to predict the design resistance of hollow prestressed concrete bridge columns.

A Study on the Measurement for Table Deflection using Laser Interferometer and Simulation (레이저를 이용한 테이블 처짐 측정과 시뮬레이션에 관한 연구)

  • 김민주
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.8 no.6
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    • pp.55-63
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    • 1999
  • The acceleration of the performance of machine tools influences the development of the semi-conductor and optical technology as the development of NC and measurement technology. Because the measurement has been done to unload condition without considering of mechanical stiffness in the case of machining center as we measure the quasi-static error of machine tools on general study people who works on the spot has many problems on the data value. Also there are no satisfiable results until now in spite of many studys about this because the deflections of the table and the shaft supporting a workpiece influence, influence the accuracy of the table and shaft supporting a workpiece influence the accuracy of the workpiece. And there is doubt about the inspection method of measured error. In this paper Therefor we will help working more accurately on the spot by measuring analyzing displaying the defoec-tion of the table and support shaft when we load on the table and the support shaft of machining center using laser interfer-ometer. Also we try to settle new conception of the measurement method and more accurate grasp of the deflection tenden-cy by verifing the tendency of the error measured through the comparison of the simulated error measured through the comparison of the simulated error using ANSYS a common finite element analysis program which is able to measure heat deformation material deformation and error resulted from this study.

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Advanced Evaluation of In-situ Strength using CPT results (콘관입시험을 이용한 지반강도의 상세평가해석)

  • Lee, Jun-Hwan;Kang, Byung-Jun;Kyung, Doo-Hyun;Hong, Jung-Mu
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.10a
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    • pp.111-116
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    • 2008
  • 콘관입시험(CPT)은 의사정적상태로 수행되는 현장시험방법으로서, 각종 기초구조물의 설계와 더불어 지반조사를 위한 대표적 방법으로 널리 적용되고 있다. 본 논문에서는 콘관입시험결과를 이용하여 사질토 지반에 있어서 지반강도의 상세평가법을 제안하고자 한다. 사질토의 강도는 상대밀도와 응력상태에 따라 변하는 상태의존적 성질을 나타내고 있으나, 이러한 역학적 성질은 실험실 내에서만 측정이 가능한 상태이며, 현장강도의 경험식이나, 대표강도의 평가만이 제안되어 있는 실정이다. 따라서 본 연구에서는 대표적 현장시험방법인 CPT를 이용하여 다이러턴시 특성 평가가 가능하며, 다양한 지반특성치가 반영될 수 있는 현장강도의 상세평가법을 제안하고자 한다. 이를 위해 실내삼축압축시험을 통해 얻어진 강도특성과 역학특성치들을 분석하였으며, 이를 토대로 수정 다일러턴시 평가법을 제안하였다. 제안된 방법의 검증을 위해 가압토조를 이용한 콘관입시험을 수행하였으며, 측정값과의 비교분석을 수행하였다.

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Paratic Impedance Extraction of FC-PGA Package Pin using the Static Fast Multipole Method (Static FMM을 이용한 FC-PGA 패키지 핀에서의 기생 임피던스 추출)

  • 천정남;이정태;어수지;김형동
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.12 no.7
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    • pp.1076-1085
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    • 2001
  • In this paper, the FMM(Fast Multipole Method) combined with GMRES(Generalized Minimal RESidual Method) matrix solver is used to extract the parasitic impedance for complicated 3-D structures in uniform dielectric materials which limit the use of MoM(Method of Moment) due to its large computation time and memory requirement. This algorithm is a fast multipole-accelerated method based on quasistatic analysis and is very efficient for computing impedance between conductors. This paper proved the accuracy and efficiency of the FMM by comparing with MoM in simple examples. Finally the parasitic impedance of FC-PGA(Flip Chip Pin Grid Array) Package pins has been extracted by this algorithm and we have considered the possibility of the EMI/EMC problem caused by the signal interference.

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The Estimation of Fatigue Strength of Structure with Practical Dynamic Force by Inverse Problem and Lethargy Coefficient (구조물의 피로강도평가를 위한 역문제 및 무기력계수에 의한 실동하중해석)

  • 양성모;송준혁;강희용;노홍길
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.1
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    • pp.106-113
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    • 2004
  • Most of mechanical structures are composed of many substructures connected to one another by various types of mechanical joints. In automotive engineering, it is important to study these connected structures under various dynamic forces for the evaluations of fatigue life and stress concentration exactly. In this study, the dynamic response of vehicle structure to external forces is classified an inverse problem involving strains from the experiment and the analysis. The practical dynamic forces are determined by the combination of the analytical and experimental method with analyzed strain by quasi-static finite element analysis under unit force and with measured strain by a strain gage under driving load, respectively. In a stressed body, inter-molecular chemical bonds are failed beyond the certain magnitude. The failure of molecular structure in material is considered as a time process of which rate is determined by mechanical stress. That is, the failure of inter-molecular chemical bonds is the fatigue lift of material. This kinetic concept is expressed as lethargy coefficient. And S-N curve is obtained with the lethargy coefficient from quasi-static tensile test. Equivalent practical dynamic force is obtained from the identification of practical dynamic force for one loading point. Using the practical dynamic force and S-N curve, fatigue life of a window pillar is analyzed with FEM under the identified force by the procedure of above mentioned.

FEA for RC Beams Partially Flexural Reinforced with CFRP Sheets (CFRP 시트로 부분 휨 보강된 철근콘크리트 보의 유한요소해석)

  • Kim, Kun-Soo;Park, Ki-Tae;Kim, Byeong Cheol;Kim, Jaehwan;Jung, Kyu-San
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.24 no.5
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    • pp.9-16
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    • 2020
  • A CFRP sheet has been applied as a structural reinforcement in the field, and various studies are conducted to evaluate the effect of CFRP sheets on reinforced concrete. Although many experiments were performed from previous studies, there are still limitations to analyze structural behaviors with various parameters in experiments directly. This study shows the FEA on structural behaviors of RC beams reinforced with CFRP sheets using ABAQUS software. To simulate debonding failure of CFRP sheets which is a major failure mode of RC beam with CFRP sheets, a cohesive element was applied between the bottom surface of RC beam and CFRP sheets. Both quasi-static method and 2-D symmetric FE model technique were performed to solve nonlinear problems. Results obtained from the FE models show good agreements with experimental results. It was found that reinforcement level of CFRP sheets is closely related to structural behavior of reinforced concrete including maximum strength, initial stiffness and deflection at failure. Also, as over-reinforcement of CFRP sheets could give rise to the brittle failure of RCstructure using CFRP sheets, an appropriate measure should be required when installing CFRP sheets in the structure.

Type in Motion as a Visual Storytelling (Visual Storytelling으로서의 Type in Motion에 관한 연구)

  • 박효신
    • Archives of design research
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    • v.13 no.3
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    • pp.235-244
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    • 2000
  • The form or interpretation of today's communication design lies in content development and storytelling to the designer. However, the understanding as well as exteriment of the mechanisms behind content creation remain an obscure concept. Particularly given the rapid development of digital technology, since the 1980s typography has been quickly transforming itself from its static state to the more dynamic'Type in Motion'. following this came the need for solid research in'Type in Motion'as the best means of presenting story content and form The previous passage has studied the effectiveness of'Type in Motion'in presenting this kind of content. Type in Motion has allowed vast developments in the methods of story presentation. It is Due that today's digital technology has given many benefits to the designer, but on the other hand, it has required a more diverse understanding of digital design. furthermore, even the designers in digital typography lack the understanding and research in'Type in Motion'not only as a mode of visual language but also of verbal language. Given this point· in hand, the entire interpretation and interrelation of story and'Type in Motion'can be considered essential, given their shaping of effective digital typography.

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Study on Optimum Design of FPSO Spread Mooring System (FPSO 다점 계류 시스템의 최적 설계 연구)

  • Lim, Yu-Chang;Kim, Kyung-Su;Choung, Joon-Mo;Kim, Jae-Woo;Kim, Jin-Tae;Yeo, Seung-Hoon
    • Journal of Ocean Engineering and Technology
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    • v.23 no.6
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    • pp.61-66
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    • 2009
  • For a spread-moored FPSO (Floating Production, Storage, & Off-loading) subjected to environmental excitation from waves, current, and wind, a procedure to determine optimum length and stiffness of mooring lines is suggested using quasi-static frequency domain response analyses. Coupled relations between design parameters are closely examined. In consideration of this, optimized design parameters are proposed based on minimum weight condition. The initial design parameters for numerical analyses are calculated using the static catenary equation of mooring lines. It is demonstrated the line tension and vessel's offset are influenced by the mooring line length and stiffness. Accordingly it is suggested the optimum vessel's offset range should be determined considering line fatigue damage. The availability and limitation of the application of quasi-static analysis method for spread mooring system are explained by comparing the result of time domain analysis with one of frequency domain analysis.

Effective Arrangement of Non-explosive Demolition Agents and Empty Holes for Improving Fragmentation of Square Concrete Structures (정사각형 콘크리트 구조물의 파쇄도 향상을 위한 비폭성 파쇄제와 천공 홀의 효과적인 배치)

  • Cho, Hwangki;Nam, Yunmin;Kim, Kyeongjin;Lee, Jaeha;Sohn, Dongwoo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.30 no.2
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    • pp.145-151
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    • 2017
  • As an alternative to conventional explosive methods for demolition of concrete structures and rocks, the use of non-explosive demolition agents can be considered to reduce noise, vibration, and dust emissions during the demolition process. In this study, we conduct finite element analysis for crack initiation and propagation caused by the expansion of non-explosive demolition agents in square concrete structures. The predicted crack patterns are compared with the experimental results in the literature. The minimum values of the required expansion pressure of non-explosive demolition agents are also estimated, which depend upon the arrangement of non-explosive demolition agents and empty holes. Furthermore, we investigate the effect of empty holes on the fragmentation of concrete structures, and discuss the effective arrangement of non-explosive demolition agents and empty holes for fragmentation improvement.

Development of quasi-static analysis program for catenary mooring system using OpenFOAM (OpenFOAM을 이용한 catenary 계류시스템의 준정적 해석 프로그램 개발)

  • Choi, Jun Hyeok;Lee, Seung Jae
    • Journal of Ocean Engineering and Technology
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    • v.31 no.4
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    • pp.274-280
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    • 2017
  • Generally, global performance analysis in offshore platforms is performed using potential-based numerical tools, which neglect hydrodynamic viscous effects. In comparison with the potential theory, computational fluid dynamics (CFD) methods can take into account the viscous effects by solving the Navier-Stokes equation using the finite-volume method. The open-source field operation and manipulation (OpenFOAM) C++ libraries are employed for a finite volume method (FVM) numerical analysis. In this study, in order to apply CFD to the global performance analysis of a hull-mooring coupled system, we developed a numerical wave basin to analyze the global performance problem of a floating body with a catenary mooring system under regular wave conditions. The mooring system was modeled using a catenary equation and solved in a quasi-static condition, which excluded the dynamics of the mooring lines such as the inertia and drag effects. To demonstrate the capability of the numerical basin, the global performance of a barge with four mooring lines was simulated under regular wave conditions. The simulation results were compared to the analysis results from a commercial mooring analysis program, Orcaflex. The comparison included the motion of the barge, catenary shape, and tension in the mooring lines. The study found good agreement between the results from the developed CFD-based numerical calculation and commercial software.