• Title/Summary/Keyword: 연성도 평가

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Analytical Study on Flexural Behavior of Alkali-Activated Slag-Based Ultra-High-Ductile Composite (알칼리활성 슬래그 기반 초고연성 복합재료의 휨거동 해석)

  • Lee, Bang Yeon
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.7 no.2
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    • pp.158-165
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    • 2019
  • The purpose of this study is to investigate analytically the flexural behavior of beam reinforced by an alkali-activated slag-based fiber-reinforced composite. The materials and mixture proportion were selected to manufacture an alkali-activated slag-based fiber-reinforced composite with high tensile strain capacity over 7% and compressive strength and tension tests were performed. The composite showed a compressive strength of 32.7MPa, a tensile strength of 8.43MPa, and a tensile strain capacity of 7.52%. In order to analyze the flexural behavior of beams reinforced by ultra-high-ductile composite, nonlinear sectional analysis was peformed for four types of beams. Analysis showed that the flexural strength of beam reinforced partially by ultra-high-ductile composite increased by 8.0%, and the flexural strength of beam reinforced fully by ultra-high-ductile composite increased by 24.7%. It was found that the main reason of low improvement in flexural strength is the low tensile strain at the bottom of beam. The tensile strain at bottom corresponding to the flexural strength was 1.38% which was 18.4% of tensile strain capacity of the composite.

Seismic Capacity according to Structural System of High-rise Apartment (고층 아파트 구조시스템에 따른 내진성능 분석)

  • Lee, Minhee;Cho, So-Hoon;Kim, Jong-Ho;Kim, Hyung-Do
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.32 no.3
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    • pp.149-154
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    • 2019
  • The structural system of domestic high-rise apartments can be divided into two parts; the core wall system, which is composed of walls concentrated in the center and the shear wall system, which comprises a great number of walls distributed in the plan. In order to analyze the lateral behavior of each system, buildings with typical domestic high-rise apartment plans were selected and nonlinear static analysis was performed to investigate the their collapse mechanism. From the force-displacement relation derived from nonlinear static analysis, response modification factor was evaluated by calculating the overstrengh and ductility factor, which are important in the seismic response. The ductility of core wall system is small, but as it is governed by wind load, its overstrength is greatly estimated, and its response modification factor is calculated by the overstrengh factor. Due to a large number of walls, shear wall system has a large ductility, making the response modification factor considerably large.

Performance Sensitivity of Flexible Barriers to Input Parameters (연성 방호구조물의 입력변수에 대한 동적 퍼포먼스 민감도 분석)

  • Yi, Gyu-Sei
    • Journal of the Korean Society of Hazard Mitigation
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    • v.10 no.3
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    • pp.13-20
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    • 2010
  • To evaluate the performance of safety apparatus without the full scale crash test, the computer simulation is inevitable. But, to improve the accuracy of computer simulation, it is important to reasonably determine the input parameters in which the interaction of vehicle-guardrail-soil should be accounted for. This study is focused on how to enhance the reliance of the dynamic performance of guardrail obtained by computer simulation. Analyses were done on the sensitivity of output variables to the change of input parameters by using BARRIER VII of which the usefulness was proved on the barrier-vehicle impact analysis. Through the analyses important input parameters, which give sensitive effects to output of computer simulation, are found out, and methods to determine such parameters are suggested to improve the accuracy of simulation.

A Study on the Ductility of Concrete-Filled Composite Columns under Cyclic Loading (반복하중을 받는 콘크리트충전 강합성 기둥의 연성에 관한 연구)

  • 송준엽;권영봉;김성곤
    • Journal of the Earthquake Engineering Society of Korea
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    • v.5 no.6
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    • pp.11-19
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    • 2001
  • A series of test on concrete-filled composite columns was preformed to evaluate structural performance under axial compression and cyclic lateral loading. It was presented that concrete-filled composite columns had high strength, high stiffness and large energy-absorption capacity on account of mutual confinement between the steel plate and filled-in concrete. A cross section analysis procedure developed to predict the moment-curvature relation of composite columns was proven to be on accurate and effective method. The ductility factor and the response modification factor were evaluated for the seismic design of concrete-filled composite columns. It was shown that concrete-filled composite columns could be used as a very efficient earthquake-resistant structural member.

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Seismic Control of Stiffness-degrading Inelastic SDOF Structures with Fully Elasto-Plastic Dampers (강성저감형 비탄성 단자유도 구조물에 설치된 완전탄소성 감쇠기의 제진성능)

  • Park, Ji-Hun;Kim, Hun-Hee;Kim, Ki-Myon
    • Journal of the Earthquake Engineering Society of Korea
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    • v.14 no.4
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    • pp.37-48
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    • 2010
  • The seismic control effect of reinforced concrete structures with low energy dissipating capacity due to stiffness degradation is investigated through nonlinear time history analysis. The primary structure is idealized as a SDOF system of modified Takeda hysteresis rule and an elasto-perfectly-plastic nonlinear spring is added to represent a hysteretic damping device. Based on statistics of the numerical analysis, equivalent linearization techniques are evaluated, and empirical equations for response prediction are proposed. As a result, estimation of the ductility demand with proposed empirical equations is more desirable than the equivalent linearization techniques. The optimal yield strengths based on empirical equations are significantly different from the optimal yield strength of elasto-perfectly-plastic systems. Also, the results indicate that the reduction effect of the ductility demand is more remarkable for smaller natural periods.

Design of Fiber Reinforced Cement Matrix Composite Produced with Limestone Powder and Flexural Performance of Structural Members (석회석 미분말을 혼입한 시멘트계 매트릭스 섬유복합재료의 설계 및 구조부재의 휨성능)

  • Hyun, Jung-Hwan;Kim, Yun-Yong
    • Composites Research
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    • v.29 no.6
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    • pp.328-335
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    • 2016
  • The purpose of this study is to develop fiber reinforced cement matrix composite (ECC) produced with limestone powder in order to achieve high ductility of the composite, and to evaluate flexural performance of structural members made with ECC. Four kinds of mixture proportions were determined on the basis of the micromechanics and a steady state cracking theory considering the matrix fracture toughness and fiber-matrix interfacial characteristics. The mechanical properties of ECC, represented by strain-hardening behavior in uniaxial tension, were investigated. Also, strength property of the composite was experimentally evaluated. Two structural members made with ECC were produced and tested. Test results were compared with those of conventional concrete structural members. Increased limestone powder contents of ECC provides higher ductility of the composites while generally resulting in a lower strength property. ECC structural members exhibited higher flexural ductility, higher flexural load-carrying capacity and tighter crack width compared to conventional structural members.

A Study on the 1-Way FSI Analysis for Shutter of Side Jet Thruster (측추력기 Shutter의 단방향 유체-구조 연성해석에 관한 연구)

  • Ko, Jun Bok;Seo, Min Kyo;Lee, Kyeong Ho;Baek, Ki Bong;Cho, Seung Hwan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.12
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    • pp.1359-1365
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    • 2014
  • In this study, 1-way fluid structure interaction analysis(FSI) for the shutter, component of side jet thruster was performed to evaluate the safety. Driving torque to open nozzle, thermal and high pressure load of hot gas was applied to shutter. Thus, the shutter must be designed to endure this load during combustion. We carried out computational fluid dynamics analysis to obtain the pressure, temperature, and heat transfer coefficient of hot gas of side jet thruster. We then used the data as the load condition for a thermal structural analysis using a mapping method. The locations with the maximum stress and temperature distributions were found. We compared the maximum stress with the tensile stress of shutter material according to temperature to evaluate the safety. We also analyzed the radial deformation of the shutter to set the proper interface gap with the side jet thruster parts.

Parametric Study on Seismic Performance of Internally Confined Hollow CFT Column (내부 구속 중공 CFT 교각의 내진성능에 대한 매개변수 연구)

  • Yeom, Eung-Jun;Kim, Hyun-Jong;Han, Taek-Hee;Kang, Young-Jong
    • Journal of the Korean Society of Hazard Mitigation
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    • v.8 no.1
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    • pp.15-21
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    • 2008
  • The internally confined hollow-concrete filled tube (ICH-CFT) column has two tubes on the both sides (hollow part and outer part) of the concrete. The inner tube and the outer tube perform great seismic abilities, ductility and absorption of energy due to the steel tubes and the hollow part. So, the study of this column type for the practical use is needed. In this study, the qualitative analysis about seismic capacities depending on parameters is performed for the practical design of the ICH-CFT column. The parameters are diameter of column, hollow ratio and thickness of tubes with the same resistance of the moment. Also, the economical evaluation of ductility and comparison with CFT column make this study to be of practical use. Especially, a change of seismic performance depends on the hollow ratio and the thickness of the outer tube, and the economical hollow ratios according to the thickness of the outer tube in the ICH-CFT column are suggested.

Evaluation of Performance of CFRP Sheet Reinforcement on RC Members Subjected to Axial Load and Flexural Moment (축력과 휨 모멘트를 받는 RC 부재의 CFRP 시트 보강에 따른 성능 평가)

  • Bae, Chan Young;Lee, Ji Hyeong;Kim, Sang Woo;Kim, Jin Sup
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.43 no.5
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    • pp.567-576
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    • 2023
  • In general, RC beam members are designed as flexural members, considering only the bending load. However, in actual buildings, axial and bending load are simultaneously applied due to the continuity between members. As a result, the bending strength of the RC beam member increases, but the displacement decreases, and cracks are mainly concentrated in the center of the beam. Therefore, in this study, the bending performance of both normal and strengthened RC beam using carbon fiber sheets subjected to combined axial and bending load was experimentally evaluated. The carbon fiber sheets were wrapped around the middle of the specimens, and axial and bending load were applied simultaneously to the beams. The magnitude of the axial force and the effects of carbon fiber sheet reinforcement on the deformed shape, bending strength, deflection, and ductility of the RC beams were analyzed. The results show that as the applied axial force increased, the maximum bending strength increased, but the ductility decreased 64%. The bending strength of the strengthened beams increased up to 27%, the maximum deflection decreased around 8% and the ductility increased by up to 43%.

A Study on the Ring Deflection According to Compaction of Buried Polyethylene Pipes (지중매설 폴리에틸렌관의 다짐도에 따른 관변형 연구)

  • Seungcheol Baek;Seungwook Kim;Byounghan Choi;Sunhee Kim
    • Journal of the Korean GEO-environmental Society
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    • v.25 no.10
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    • pp.5-10
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    • 2024
  • Flexible pipes have the property of resisting external loads by utilizing the rigidity of the pipe and the surrounding ground, and have recently been in the spotlight because they are lighter in weight and have excellent durability compared to concrete pipes. In this study, the behavior characteristics of buried polyethylene pipe, a representative flexible pipe, were examined. Double-walled and multi-walled polyethylene pipes were used, and the structural behavior of the polyethylene pipe was evaluated based on a 5% deflection of the pipe diameter suggested in the design standards for flexible pipes. For the polyethylene pipe, the material properties of the pipe were identified through a ring stiffness test, and the behavior characteristics in the ground were reviewed through the simulation experiment of the buried polyethylene pipes. In addition, a finite element analysis model was developed based on the results of underground burial simulation experiments, and the behavior characteristics of polyethylene pipes according to backfill conditions were evaluated using the developed finite element analysis model and design equation. As a result of the study, it was confirmed that the capacity of the pipes and the compaction of the backfill are the main factors that determine the structural performance of the buried polyethylene pipe.