• Title, Summary, Keyword: modulus

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A Methodology to Determine Resilient Modulus for Crushed Rock-Soil Mixture (암버력-토사 성토의 회복탄성계수 산정방법)

  • Park, In-Beom;Kim, Seong-Su;Jung, Young-Hoon;Mok, Young-Jin
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.1190-1200
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    • 2010
  • A method was developed to determine resilient modulus for crushed rock-soil mixtures whose usage has been increased recently without engineering specifications. The method is based on the subtle different modulus called nonlinear dynamic modulus and was lately implemented in residual soils and engineered crushed-stones. Hereby. the same method was expanded to crushed rock-soil mixtures containing as large grain diameter as 300mm. The method utilize field direct-arival tests for the determination of maximum Young's modulus, and a large scale free-free resonant column test, which is recently developed to is capable to test as large grain diameter as 25mm, for modulus reduction curves. The prediction model of resilient modulus was evaluated for crushed rock-soil mixtures of a highway construction site at Gimcheon, Korea.

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Measuring Young's Modulus of Materials by using Accelerometer (가속도계를 이용한 재료의 영계수 측정방법)

  • Choi, Young-Chul;Park, Jin-Ho;Yoon, Doo-Byung;Sohn, Chang-Ho;Hwang, Il-Soon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1027-1032
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    • 2007
  • For the description of the elastic properties of linear objects a convenient parameter is the ratio of the stress to the strain, a parameter called the Young's modulus of the material. Young's modulus can be used to predict the elongation or compression of an object as long as the stress is less than the yield strength of the material. Conventional method for estimating Young's modulus measured the ratio of stress to corresponding strain below the proportional limit of a material using a tensile testing machine. But the method needs precision specimens and expensive equipment. In this paper, we proposed method for estimating Young's modulus using accelerometer. The basic idea comes from that the wave velocity is different as the Young's modulus. To obtain Young's modulus, a group velocity is obtained. It is difficult to measure group velocity. This is because plate medium has a dispersive characteristics which has different wave speed as frequency. In this paper, we used Wigner-Ville distribution to measure group velocity. To verify the proposed method, steel and acryl plate experiments have been performed. Experimental results show that the proposed method is powerful for estimating Young's modulus.

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Study on the subgrade reaction modulus$(K_{30})$ and strain modulus$(E_v)$ (지반반력계수$(K_{30})$와 변형률계수$(E_v)$에 대한 고찰)

  • Kim, Dae-Sang;Choi, Chan-Yong;Kim, Seong-Jung;Yu, Jin-Young;Yang, Sin-Chu
    • Journal of the Korean Society for Railway
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    • v.10 no.3
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    • pp.264-270
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    • 2007
  • Two modulus, strain modulus $(E_v)$ and subgrade reaction modulus $(K_{30})$ are being used as a standard for bearing stiffness in Korea Railroad design. The first is used in Europe and the other is used in Japan. The methodologies to obtain the two modulus are similar in using plate. But testing methods are different in loading to plate. Therefore, according to soil strain range, there should be large gap in not only computations of deformation modulus but also the necessary time to test. At first, this paper focuses on the two kinds of test methods to evaluate bearing stiffness. Secondly, based on elastic theory, the theory to obtain the two coefficients are studied thoroughly. Finally, the correlations between the two coefficients were analyzed and evaluated based on the field test results more than 38 places. The matching values for subgrade and ground between $K_{30}$ and $E_{v2}$ are proposed with the consideration of the proposed strain reduction factor (1.5 for subgrade and 3 for ground) and safety factor, respectively.

A Experimental Study on Application of KS F 2456 using Shear Wave (급속 동결 융해에 대한 콘크리트의 저항 시험방법(KS F 2456)에 전단파 적용을 위한 실험적 연구)

  • An, Ji-Hwan;Jeon, Sung-Il;Kwon, Soo-Ahn
    • International Journal of Highway Engineering
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    • v.14 no.5
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    • pp.57-65
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    • 2012
  • PURPOSES: It is important to consider the long-term performance of concrete pavement, because concrete pavement is more exposed to the various environmental conditions than any other concrete structures. One of the several methods to evaluate the long-term performance of concrete during winter is KS F 2456. Relative dynamic modulus of elasticity shows the resistance to freezing and thawing. METHODS: To measure relative dynamic modulus of elasticity, ultra sonic is generally used. But in this study, to measure the relative dynamic modulus of elasticity, both ultra sonic and shear wave were used and then compared each other. RESULTS: The results from the measurement by ultrasonic wave and shear wave were divided into three types. Type 1 : Specimens are good and relative dynamic modulus of elasticity did not decrease until 300 cycle. Type 2 : The relative dynamic modulus of elasticity decreased from the late cycle.(about 150 cycle later) Type 3 : The relative dynamic modulus of elasticity consistently decreased from the beginning. As a result of ANOVA, there is no difference according to measuring method, in type 2 and 3. But there is a difference according to measuring method, in type 1's relative dynamic modulus of elasticity. CONCLUSIONS: It is proved that shear wave can be used to understand the damage tendency of relative freezing and thawing and to measure the relative dynamic modulus of elasticity.

Laboratory Performance Evaluation of High Modulus Asphalt Mixes for Long-Life Asphalt Pavements (장수명 아스팔트 포장용 고강성 혼합물의 실내 공용성 평가)

  • Kang, Min Gyun;Lee, Jung Hun;Lee, Hyun Jong;Choi, Ji Young
    • Journal of The Korean Society of Civil Engineers
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    • v.26 no.1D
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    • pp.73-79
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    • 2006
  • A major purpose of this study is to develop high modulus asphalt mixtures for perpetual asphalt pavements which can save maintenance cost by increasing the design and performance periods of the pavements. Various physical and mechanical laboratory tests are performed for the high modulus asphalt binder developed in this study. The test results show that the properties of the high modulus binder are similar to those of the French high modulus binders. In addition to the binder tests, various performance tests are conducted for the high modulus and conventional mixtures. The dynamic modulus test results indicate that the dynamic modulus values of the high modulus mixtures are higher than those of the conventional mixtures by 10~15% at $5^{\circ}C$, 20~25% at $15^{\circ}C$ and 100% at $30^{\circ}C$. It is observed from the performance tests that the high modulus mixtures yield better fatigue, rutting and moisture damage performance than the conventional mixtures.

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Estimation of Pile Shaft Resistances with Elastic Modulus Depending on Strain (변형률에 따른 탄성계수 변화를 고려한 말뚝의 주면지지력 산정)

  • Kim, Seok-Jung;Kim, Sung-Heon;Jung, Sung-Jun;Kwon, Oh-Sung;Kim, Myoung-Mo
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.933-943
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    • 2009
  • Axial loads and shaft resistances can be calculated by load transfer analysis using strain data with load level. In load transfer analysis, the elastic modulus of concrete is a one of the most important parameters to consider. The elastic modulus, $E_{50}$, suggested by ACI (American Concrete Institute), has been commonly used. However, elastic modulus of concrete shows nonlinear stress-strain characteristic, so nonlinearity should be considered in load transfer analysis. In this paper, a load transfer analysis was performed by using data obtained from bi-directional pile load tests for four cases of drilled shafts. For consideration of nonlinearity, elastic modulus was calculated by both the Fellenius method and the nonlinear method, assuming the stress-strain relation of concrete to be a quadratic function, and then, the calculated elastic modulus was applied to the estimation of shaft resistance. The calculated shaft resistances were compared with the result obtained using the constant elastic modulus of ACI code. It was found that the f-w curves are similar to each method, and elastic modulus and shaft resistances decreased as strain increased. Moreover, shaft resistances estimated from elastic modulus considering nonlinearity were 5~15% different than those obtained using the constant elastic modulus.

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Effects of the Spinning Conditions on the Tangent Modulus-Strain Culves of Polypropylene Monofilaments (방사 조건이 폴리프로필렌 모노필라멘트의 탄젠트 탄성률-변형률 곡선에 미치는 영향)

  • Im, Jeong-Ryeol;Sim, Hyeon-Ju;Kim, Sang-Yong
    • Textile Science and Engineering
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    • v.31 no.2
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    • pp.129-142
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    • 1994
  • The effects of spinning conditions on the tangent modulus-strain curves have been studied using isotactic polypropylene(iPP) mononlaments. The tangent modulus-strain curve, which is derived from the first derivative of the true stress-strain curve, showed three distinct peaks. The tangent modulus of the first and the second peak in the tangent modulus-strain curve were increased as the draw ratio and the spinning speed were increased. The tensile strain of the first peak had little dependence on the process conditions, however, that of the second peak decreased above the natural draw ratio. The spinning conditions had little effect on the tangent modulus of the third peak, while the tensile strain of the third peak decreased as the draw ratio was increased. The variation of the isotactic helix content in iPP monofilament, determined from the FIIR spectra, was in agreement with that of the tangent modulus-strain curve with the tensile strain.

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A Proposal of an Elastic Modulus Equation for High-Strength and Ultra High-Strength Concrete

  • Jang, II-Young;Park, Hoon-Kyu;Yoon, Young-Soo
    • International Journal of Concrete Structures and Materials
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    • v.18 no.1E
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    • pp.43-48
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    • 2006
  • This paper presents an elastic modulus equation more appropriate for predicting the elastic modulus of structural materials designed for and made of high- and ultra high-strength concrete under current domestic situation in Korea. In order to validate and assess the proposed elastic modulus equation, more than 400 laboratory test data available in the domestic literature on compressive strength of concrete in the range between 400 to 1,000 $kgf/cm^2$ were used and analyzed statistically. Comparison analyses of the proposed elastic modulus equation with previously suggested equations of ACI363R, CEB-FIP, NS3473 and New-RC are also presented to demonstrate its applicability in domestic practice.

Prediction of tensile modulus in polymer nanocomposites containing carbon nanotubes (CNT) above percolation threshold by modification of conventional model

  • Zare, Yasser;Rhee, Kyong Yop
    • Current Applied Physics
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    • v.17 no.6
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    • pp.873-879
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    • 2017
  • In this paper, a simple model is developed to predict the tensile modulus of polymer/carbon nanotubes (CNT) nanocomposites (PCNT) above percolation threshold. Since the conventional models such as Ouali and Lyngaae-Jorgensen (L-J) cannot predict the accurate results, a developed model is presented which calculates proper modulus as a function of aspect ratio (${\alpha}$) and volume fraction of CNT at percolation threshold (${\phi}_p$). The developed model can present accurate data, which agree with the experimental results at all filler concentrations. The high ranges of "${\alpha}$" and low values of "${\phi}_p$" achieve a desirable modulus. However, a high "${\phi}_p$" causes the poor modulus at different "${\alpha}$" demonstrating that the role of "${\alpha}$" is highlighted at slight "${\phi}_p$". It is also possible to calculate the "${\alpha}$" and "${\phi}_p$" parameters by applying the developed model to the experimental data of modulus.

Estimation of compressibility for Busan clay by CPT (CPT를 이용한 부산점토의 압축특성에 관한 연구)

  • Hong, Sung-Jin;Lee, Moon-Joo;Shim, Seong-Hyeon;Lee, Woo-Jin
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.320-325
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    • 2009
  • The constrained modulus, representative property to evaluate compressibility of soil, is needed to estimate the settlement of ground structure. A series of lab and field cone penetration tests for clayey soil of Busan new-port and Noksan industrial area were conducted to evaluate the estimation method of constrained modulus. Since CPT generates large deformation of ground, it is difficult to correlate the cone resistance with the constrained modulus. Therefore, appropriate correlation between them is essential to estimate the constrained modulus based on CPT results. The test results show that the ratio of the constrained modulus to the cone resistance is inversely proportional with plasticity index. Based on this result, the estimation method of constrained modulus for Busan clay is suggested.

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