• Title, Summary, Keyword: compressive strain

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Eartqyake-Resistance of SlenderShear Wall With no Boundary Confinement (단부 횡보강이 없는 세장한 전단벽의 내진성능)

  • 박홍근;강수민;조봉호;홍성걸
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.375-380
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    • 2000
  • Experimental and numerical studies were done to investigate seismic performance of slender sheat wall with no boundary confinement. 1/3 scale-specimens that model the plastic region of long slender shear walls subjected to combined axial load and bending moment were rested to investigate strength, ductility, capacity of energy dissipation and strain distribution. The experimental results show that the slender walls fail due to early crushing in the compressive boundary, and then have very low ductility. The measured maximum compressive strain is 0.0021, which is much less then 0.004 being commonly used for estimation of ductility. The experimental results indicates that the maximum compressive strain is not a fixed value but is affected by moment gradient along the shear wall height and distance from neutral axis to the extreme compressive fiber.

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W/C Ratio Effects on Mechanical Properties of High Performance hybrid SC and PE Fibers Reinforced Cement Composites (물-시멘트비에 따른 하이브리드 섬유보강 고인성 시멘트 복합체의 역학적 특성)

  • Yun, Hyun-Do;Kim, Sun-Woo;Cheon, Esther;Lee, Sang-Soo
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.118-121
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    • 2006
  • The research reported here is concerned with the effects of the fiber combination condition and water/cement ratio on the mechanical properties of high performance fiber-reinforced cementitious composites(HPFRCC). An experimental investigation of the behavior of steel cords(SC) and SC and Polyethylene(PE) hybrid fiber reinforced cementitious material under compressive and tensile loading is presented. In this experimental research, the tensile and compressive strength and strain capacity of HPFRCC were selected using the cylindrical specimens. The results show that W/C ratio is a significant effect factor on the compressive and tensile performance of HPFRCC. The envelope curve concept applies to hybrid fiber-reinforced cementitious composites in tension just as it does to compressive stress-strain curve of fiber-reinforced cement composites. For practical purposes, the tensile envelope curve may be taken to be the same as the monotonic tensile stress-strain curve.

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Material Nonlinear Behavior and Microstructural Transition of Porous Polyurethane Foam under Uniaxial Compressive Loads (일축 압축하중 하 다공성 폴리우레탄폼의 재료비선형 거동 및 미세구조 변화)

  • Lee, Eun Sun;Goh, Tae Sik;Lee, Chi-Seung
    • Korean Journal of Materials Research
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    • v.27 no.12
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    • pp.688-694
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    • 2017
  • Porous materials such as polymeric foam are widely adopted in engineering and biomedical fields. Porous materials often exhibit complex nonlinear behaviors and are sensitive to material and environmental factors including cell size and shape, amount of porosity, and temperature, which are influenced by the type of base materials, reinforcements, method of fabrication, etc. Hence, the material characteristics of porous materials such as compressive stress-strain behavior and void volume fraction according to aforementioned factors should be precisely identified. In this study, unconfined uniaxial compressive test for two types of closed-cell structure polyurethane foam, namely, 0.16 and $0.32g/cm^3$ of densities were carried out. In addition, the void volume fraction of three different domains, namely, center, surface and buckling regions under various compressive strains (10 %, 30 %, 50 % and 70 %) were quantitatively observed using Micro 3D Computed Tomography(micro-CT) scanning system. Based on the experimental results, the relationship between compressive strain and void volume fraction with respect to cell size, density and boundary condition were investigated.

Unconfined Compression Strengh Characteristics and Degree of Disturbance of Busan Marine Clay (부산 해성 점토의 일축압축강도 특성 및 교란도에 관한 연구)

  • Kim, Byoung-Il;Lee, Seung-Won;Lee, Seung-Hyun;Cho, Sung-Min
    • Journal of Korean Society of Hazard Mitigation
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    • v.5 no.4
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    • pp.29-36
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    • 2005
  • In this study, relations among unconfined compressive strength, strain at maximum strength and depth were compared with each other. Test specimen is marine clay originated from the place near Ga-duck island in Busan city. In addition, influence of impure material contained in specimen and that of total core recovery(TCR) on unconfined compressive strength and degree of disturbance were investigated. As a result of tests, unconfined compressive strength decreases as strain corresponding to maximum strength increases. Also, the deeper the sampling depth and the bigger the TCR, the unconfined compressive strength increases. Especially, as the TCR increases, the unconfined compressive strength Increases and quality of specimen is enhanced.

The effect of active and passive confining pressure on compressive behavior of STCC and CFST

  • Nematzadeh, Mahdi;Fazli, Saeed
    • Advances in concrete construction
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    • v.9 no.2
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    • pp.161-171
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    • 2020
  • In this paper, an experimental study was conducted on the compressive behavior of steel tube confined concrete (STCC) and concrete-filled steel tube (CFST) columns with active and passive confinement. To create active confinement in the STCC and CFST specimens, an innovative method was used in this study, in which by applying pressure on the fresh concrete, the steel tube was laterally pretensioned and the concrete core was compressed simultaneously. Of the benefits of this technique are improving the composite column behavior, without the use of additives and without the need for vibration, and achieving high prestressing levels. To achieve lower and higher prestressing levels, short and long term pressures were applied to the specimens, respectively. Nineteen STCC and CFST specimens in three groups of passive, short-term active, and long-term active confinement were subjected to axial compression, and their mechanical properties including the compressive strength, modulus of elasticity and axial strain were evaluated. The results showed that the proposed method of prestressing the STCC columns led to a significant increase in the compressive strength (about 60%), initial modulus of elasticity (about 130%) as well as a significant reduction in the axial strain (about 45%). In the CFST columns, the prestressing led to a considerable increase in the compressive strength, a small effect on the initial and secant modulus of elasticity and an increase in the axial strain (about 55%). Moreover, increased prestressing levels negligibly affected the compressive strength of STCCs and CFSTs but slightly increased the elastic modulus of STCCs and significantly decreased that of CFSTs.

A Study on Dynamic Material Properties of Functional High Explosive Formulation Simulant Subjected to Dynamic Loading (동적하중을 받는 기능성 고폭화약조성 시뮬런트 재료물성 연구)

  • Park, Jungsu;Yeom, Kee Sun;Park, Chunghee;Jeong, Sehwan;Lee, Keundeuck;Huh, Hoon
    • Journal of the Korea Institute of Military Science and Technology
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    • v.16 no.6
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    • pp.857-866
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    • 2013
  • This paper is concerned with the material properties of functional high explosive(FHX) simulant at various strain rates ranging from $10^{-4}/sec$ to $10^1/sec$. Material properties of FHX at high strain rates are important in prediction of deformation modes of FHX in a warhead which undergoes dynamic loading. Inert FHX stimulant which has analogous mechanical properties with FHX was utilized for material tests due to safety issues. Uniaxial tensile tests at quasi-static strain rates ranging from $10^{-4}/sec$ to $10^{-2}/sec$ and intermediate strain rates ranging from $10^{-1}/sec$ to $10^1/sec$ were conducted with JANNAF specimen using a tensile testing machine, INTRON 5583, and developed high speed material testing machine, respectively. Uniaxial compressive tests at quasi-static strain rates and intermediate strain rates were conducted with cylindrical specimen using a dynamic materials testing machine, INSTRON 8801. And cyclic compressive loading tests were performed with various strain rates and strains. Deformation behaviors were investigated using captured images obtained from a high-speed camera.

Creep Behavior of Reinforced Clayey Soil (보강 점성토의 크리이프 특성(지반공학))

  • 이상호;최재원;차현주
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • pp.484-489
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    • 2000
  • This study was performed to examine the characteristic of creep behavior by reinforced clayey soil. So, it was carried out measurement of compressive strain and poisson's ratio by the reinforced soil mixtures. At each specimen was made by added calcium carbonate and 19mm length monofilaments into soil at designated ratio, and it was measured during the age of 30 days right after manufacturing the specimens. Because monofilaments controled increase of friction and dry shrinkage of soil into soil, compressive strain of monfilments reinforced soil with mixing rate of 0.3% is low value. And Because void was formed by compressive, vertical strain and horizontal strain of calcium carbonate reinforced soil with rate of 9% is high value.

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The Mechanical Properties of High-Strength Concrete-The Effect of Strain Rate and the Tensile Strength- (고강도콘크리트의 재료역학적 특성 연구-변형도율과 인장강도를 중심으로-)

  • 김진근;박찬규;박연동
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.111-118
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    • 1992
  • The mechanical behaviors related to the strain rate effect and the tensile strength of high-strength concrete were investigated in this study. For this purpose, concrete cylinder specimens with 4 different compressive strengths from 232kg/$\textrm{cm}^2$ to 1113kgf/$\textrm{cm}^2$ were tested and analysed on the mechanical properties(stress-strain relationship, compressive, modulus of elasticity, strain at peak compressive stress). From this experimental and analytical study, it seems that the current prediction model(ACI) for modulus of rupture need to be refined. Therefore, more refined equations for evaluation tensile strength of concrete are proposed.

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Dynamic deformation behavior of Ethylene Copolymer under high strain rate compressive loading (SHPB 기법을 사용한 고변형률 속도 하중하에서의 합성수지의 동적 변형 거동)

  • Lee, Jong-Won;Lee, Ouk-Sub;Hwang, Si-Won;Kim, S-Hyun
    • Proceedings of the KSME Conference
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    • pp.371-376
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    • 2004
  • It is well known that a specific experimental method such as the Split Hopkinson Pressure Bar (SHPB) technique is the simplest experimental technique to determine the dynamic material properties under the impact compressive loading conditions with strain-rate of the order of $10^3/s{\sim}10^4/s$. This type of experimental procedure has been widely used with proper modification on the test setups to determine the varying dynamic response of materials for the dynamic boundary conditions such as tensile and fracture as well. In this paper, dynamic compressive deformation behaviors of an Ethylene Copolymer materials widely used for the isolation of vibration from varying structures under dynamic loading are estimated using the SHPB technique.

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Dynamic Deformation Behavior of Rubber and Ethylene Copolymer Under High Strain Rate Compressive Loading (SHPB기법을 사용한 고무와 합성수지의 고변형률 속도 하중 하에서의 동적 변형 거동)

  • 이억섭;이종원;김경준
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.6
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    • pp.122-130
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    • 2004
  • It is well known that a specific experimental method, the Split Hopkinson Pressure Bar (SHPB) technique is a best experimental technique to determine the dynamic material properties under the impact compressive loading conditions with strain-rate of the order of 10$^3$/s∼10$^4$/s. This type of experimental procedure has been widely used with proper modification on the test setups to determine the varying dynamic response of materials for the dynamic boundary conditions such as tensile and fracture as well. In this paper, dynamic compressive deformation behaviors of a rubber and an Ethylene Copolymer materials widely used for the isolation of vibration from varying structures under dynamic loading are estimated using a Split Hopkinson Pressure Bar technique.