• Title, Summary, Keyword: dynamic properties

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Dynamic Analysis of Existing Rockfill Dam Using Dynamic Properties by Field Test and Geophysical Exploration (실측 동적물성을 이용한 기존 사력댐의 동적거동분석)

  • Lee, Jong-Wook;Oh, Byung-Hyun
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.306-313
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    • 2005
  • For seismic response analysis of rockfill dam, dynamic material properties, by field test, are needed. Density and elastic wave profiles have to be known to get an information of the material properties of structure. In this study, various field tests are applied to the example of rockfill dam to get an information of dynamic material properties and seismic safety is evaluated by seismic response analysis with the result of field tests.

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Dynamic behavior investigation of scale building renovated by repair mortar

  • Basaran, Hakan
    • Computers and Concrete
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    • v.16 no.4
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    • pp.531-544
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    • 2015
  • The objective of this study was to examine the effect of repair mortar on the dynamic properties such as natural frequencies, mode shape and damping ratios of two story single span scale reinforced concrete building. To this end, two story single span scale reinforced concrete building having dimensions of 150 cm (width), 150 cm (length) and 135 cm (height) was constructed. Workmanship defects such as separation of material, faulty vibration application and bad gradation of the structure were properly evaluated. Dynamic properties of damaged structure were experimentally determined using Operational Modal Analysis (OMA). Detected defects in the structure were fixed by plastering with repair mortar. Dynamic properties of repaired structure were reevaluated by using the OMA method. Finite element software called Abaqus was used to numerically determine dynamic properties of the structure. Structure modeled as solid was subjected to Linear Perturbation Frequency Method. The changes in dynamic properties of structure after the repair process were comparatively studied by evaluating experimental and numerical results.

Effects of stiffening rings on the dynamic properties of hyperboloidal cooling towers

  • Zhang, Jun-Feng;Chen, Huai;Ge, Yao-Jun;Zhao, Lin;Ke, Shi-Tang
    • Structural Engineering and Mechanics
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    • v.49 no.5
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    • pp.619-629
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    • 2014
  • As hyperboloidal cooling towers (HCTs) growing larger and slender, they become more sensitive to gust wind. To improve the dynamic properties of HCTs and to improve the wind resistance capability, stiffening rings have been studied and applied. Although there have been some findings, the influence mechanism of stiffening rings on the dynamic properties is still not fully understood. Based on some fundamental perceptions on the dynamic properties of HCTs and free ring structures, a concept named "participation degree" of stiffening rings was proposed and the influence mechanism on the dynamic properties was illustrated. The "participation degree" is determined by the modal deform amplitude and latitude wave number of stiffening rings. Larger modal deform amplitude and more latitude waves can both result in higher participation degree and more improvement to eigenfrequencies. Also, this concept can explain and associate the pre-existing independent findings.

Glass powder admixture effect on the dynamic properties of concrete, multi-excitation method

  • Kadik, Abdenour;Boutchicha, Djilali;Bali, Abderrahim;Cherrak, Messaouda
    • Structural Engineering and Mechanics
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    • v.74 no.5
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    • pp.671-678
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    • 2020
  • In this work, the dynamic properties of a high performance concrete containing glass powder (GP) was studied. The GP is a new cementitious material obtained by recycling waste glass presenting pozzolanic activity. This eco-friendly material was incorporated in concrete mixes by replacing 20 and 30% of cement. The mechanical properties of building materials highly affect the response of the structure under dynamic actions. First, the resonant vibration frequencies were measured on concrete plate with free boundary conditions after 14, 28 and 90 curing days by using an alternative vibration monitoring technique. This technique measures the average frequencies of several excitations done at different points of the plate. This approach takes into account the heterogeneity of a material like concrete. So, the results should be more precise and reliable. For measuring the bending and torsion resonant frequencies, as well as the damping ratio. The dynamic properties of material such as dynamic elastic modulus and dynamic shear modulus were determined by modelling the plate on the finite element software ANSYS. Also, the instantaneous aroused frequency method and ultrasound method were used to determine the dynamic elastic modulus for comparison purpose, with the results obtained from vibration monitoring technique.

Dynamic Magneto-mechanical Behavior of Magnetization-graded Ferromagnetic Materials

  • Chen, Lei;Wang, Yao
    • Journal of Magnetics
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    • v.19 no.3
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    • pp.215-220
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    • 2014
  • This study investigates the dynamic magneto-mechanical behavior of magnetization-graded ferromagnetic materials Terfenol-D/FeCuNbSiB (MF). We measure the dynamic magneto-mechanical properties as a function of the DC bias magnetic field ($H_{dc}$). Our experimental results show that these dynamic magneto-mechanical properties are strongly dependent on the DC bias magnetic field. Furthermore, the dynamic strain coefficient, electromechanical resonance frequency, Young's moduli, and mechanical quality factor of Terfenol-D/FeCuNbSiB are greater than those of Terfenol-D under a lower DC bias magnetic field. The dynamic strain coefficient increases by a factor of between one and three, under the same DC bias magnetic field. In particular, the dynamic strain coefficient of Terfenol-D/FeCuNbSiB at zero bias achieves 48.6 nm/A, which is about 3.05 times larger than that of Terfenol-D. These good performances indicate that magnetization-graded ferromagnetic materials show promise for application in magnetic sensors.

Application and Analysis of Field Test and Geophysical Exploration for Dynamic Material Properties of Rockfill Dam (사력댐 동적물성 추정을 위한 현장조사기법 적용 및 분석)

  • Lee, Jong-Wook;Kim, Ki-Young;Jeon, Je-Sung;Cho, Sung-Eun
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.352-359
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    • 2005
  • In this study, seismic refraction survey and MASW at dam crest and down-hole test and cross hole test in the boring holes located in dam crest through the core are performed to fin out dynamic material properties, are needed to evaluate dynamic safety of rockfill dam using dynamic analysis method. From the field test and geophysical exploration, applied such as above, p-wave and s-wave velocity profile of each layer of dam body. Dynamic material properties, such as elastic modulus, shear modulus, poissong's ration, are obtained from p-wave and s-wave velocity profile and density profile from formation density logging test.

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Influence of water content on dynamic mechanical properties of coal

  • Gu, Helong;Tao, Ming;Wang, Jingxiao;Jiang, Haibo;Li, Qiyue;Wang, Wen
    • Geomechanics and Engineering
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    • v.16 no.1
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    • pp.85-95
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    • 2018
  • Water affects the mechanical properties of coal and stress wave propagation. To comprehensively investigate the effect of water content on the properties of coal, laboratory tests including X-Ray Diffraction (XRD) analysis, P-wave test, S-wave test, static and dynamic compression test with different water contents were conducted. The compressive strength, elastic modulus and failure strain and their mechanism of coal specimen under coupled static-dynamic load with the increased water content were observed. Meanwhile, energy transmission and dissipation characteristics of a stress wave in coal specimens with different water contents under dynamic load and its relation with the failure features, such as fragmentation and fractal dimension, of coal was analyzed. Furthermore, the dynamic interpretation of water infusion to prevent coal burst based on water infusion model of coal seam roadway was provided.

Characteristics of Dynamic Properties of Granite Specimen from Chungnam Yeongi Area (충남 연기군 지역 화강암 시험편의 동적물성 특성에 관한 연구)

  • Min, June-Hyun;Lee, Seung-Joong;Choi, Sung-O.
    • Tunnel and Underground Space
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    • v.21 no.6
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    • pp.480-493
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    • 2011
  • Dynamic rock property is one of most important parameters in design of earthquake-resistant structures. In this study, free-free resonant column test has been conducted to obtain dynamic Young's modulus, dynamic shear modulus, and damping ratio among dynamic properties with granite specimen of Chungnam Yeongi area. The dynamic properties obtained from this test were compared with the physical properties from static rock tests, and their relationship has been analyzed. From our study, it has been concluded that the dynamic Young's modulus and the dynamic shear modulus are linearly proportional to the elastic wave velocity. And also the damping ratio has been identified to be in non-linear inverse proportion to the elastic wave velocity.

Resonance Test for Dynamic Physical Properties of Concrete with Recycling Materials (공명진동시험을 통한 재활용재 혼입 콘크리트의 동적 물성치 측정)

  • 박용구;정영수
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.111-116
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    • 1998
  • Most previous wave tests for concrete have been done to evaluate static material properties, and thus there are less works to investigate dynamic material characteristics of concrete, which should be few in Korea. The objective of this experimental work is to investigate dynamic material characteristics of concrete, such as dynamic elastic modulus, dynamic shear modulus, first resonant frequency, dynamic poisson's ratio and etc. A dynamic Signal Analyzer has been used to perform the wave analysis for various dynamic material properties of test specimen. First Fourier transform technique has been carried out on various wave data acquired by the Resonant Column method, which is a kind of nondestructive tests. Wave analysis has been performed based on KS F2437, which is similar to ASTM C607-71 and is identical to JIS A 1127-1976.

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Identification Method of the Dynamic Characteristics of Pre-deformed Elastomers (초기 변형이 있는 방진고무의 동특성 규명 방법)

  • Ahn, Tae-Kil;Kim, Kug-Weon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.12
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    • pp.918-922
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    • 2003
  • Elastomers are extensively used in various machine design application, mainly for vibration/shock/noise control devices. However. there are still a lot of difficulties in designing the elastomeric components applied in complex shapes and under pre-deformed states. One of the most Influential factors related to mechanical properties of elastomers are pre- and dynamic strains. Consequently, a large number of experiments have to be conducted to identify dynamic properties of elastomers considering their combined effects. In this paper, we present an efficient experimental method to identify mechanical properties of elastomers considering effects of pre- and dynamic strains. This method is capable of predicting the dynamic characteristics of elastomers under arbitrary strain states from reduced experimental data.