• Title/Summary/Keyword: 충격공진법

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Detection of Inclusions in Concrete Slab by Impact-Resonance Method (충격공진법을 이용한 콘크리트 슬래브 내의 개재물 검출)

  • Kim, Hak-Hyun;Yim, Hyun-June;Lee, Kwang-Myong;Cho, Nam-Jun
    • Journal of the Korean Society for Nondestructive Testing
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    • v.20 no.3
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    • pp.221-230
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    • 2000
  • The usefulness and limitations of the impact-resonance method, which is a nondestructive evaluation (NDE) method for concrete, are studied by both experimental and theoretical methods. For the experimental study, several concrete slab specimens with various inclusions embedded were fabricated, and tested by the impact-resonance method. Some of the inclusions have been detected and accurately located, but some have not. The reasons for the failure in the latter cases have been investigated theoretically by using finite element analyses, from which the primary factors determining the success of the method have also been identified. This study will serve to enhance the understanding of the underlying physics and to improve the usefulness of the impact-resonance method as applied to concrete NDE.

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Impact-Resonance Testing of Concrete Structures (콘크리트 구조물의 충격공진 시험)

  • Kim, Young-H.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.23 no.5
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    • pp.526-531
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    • 2003
  • Condition assessment of concrete structures is essential since their performance affects public safety. Impact resonance testing has been widely used for the nondestructive testing of the concrete structures. In this article, the background, basic principles of the impact resonance testing were described. Not only laboratory studies but also the field applications such as basement concrete of large structure and large slurry wall are described.

Effect of Size Factor on Estimating Elastic Modulus of Disk-Shaped Concrete Specimen Using Impact Resonance Test (충격공진법을 이용한 콘크리트 원판 시편의 탄성계수 추정에 크기 인자가 미치는 영향)

  • Kim, Min-Suk;Son, Joeng Jin;Lee, Chang Joon;Chung, Chul-Woo
    • Journal of the Korea Institute of Building Construction
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    • v.23 no.1
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    • pp.11-22
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    • 2023
  • In this work, a depth-by-depth evaluation on the deterioration of concrete is suggested by utilizing disk shaped concrete specimens. Dynamic elastic modulus of cylindrical concrete was measured using a free-free resonance column method and compared with dynamic elastic modulus of disk-shaped concrete measured by impulse excitation technique(IET) and impact resonance(IR). According to the results of the experiment, both IET and IR methods showed a smaller difference in dynamic elastic modulus with smaller deviation in data when thickness of the disk specimen was increased. This trend was more evident from dynamic elastic modulus measured by IR method compared to that measured by IET. Variation in data was also smaller with the IR result. To increase the accuracy of the data, it is recommended to use the IR method for disk specimen with a diameter of 100mm and a thickness of 25mm.

Analysis of Dynamic and Static Elastic Modulus of In-situ Marine Concrete (현장 해양 콘크리트의 동탄성계수와 정탄성계수 분석)

  • Han, Sang-Hun;Park, Woo-Sun
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.21 no.6
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    • pp.437-443
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    • 2009
  • Impact echo method estimating the soundness of concrete measures the dynamic elastic modulus of specimens which are different with static elastic modulus tested by uni-axial compression test. Thus, this paper investigates the relationships between dynamic and static elastic modulus based on in-situ concrete cores. Also, dynamic elastic modulus was compared with compressive strength. Concrete cores were obtained from about 20 to 70 years concrete structures at three different harbors which were Incheon, Wando, and Masan in Korea. In order to investigate the influence of exposure condition on the relationship, air zone, splash zone, and tidal zone were selected. Different harbors showed the different relationships between dynamic and static elastic modulus, but exposure conditions have no influence on the relationship between dynamic and static elastic modulus. Also, the relationship between dynamic elastic modulus and compressive strength has the same tendency as the relationship between dynamic and static elastic modulus. The relationship equations were proposed to estimate the relationships properly.

Evaluation of Effects on Impact Resonance Test for Determining Modulus of Asphalt Concrete (아스팔트 콘크리트 탄성계수 결정을 위한 충격공진시험 영향요소 평가)

  • Kweon, Gi-Chul;Lee, Jae-Hoan
    • International Journal of Highway Engineering
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    • v.9 no.2 s.32
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    • pp.89-99
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    • 2007
  • The stiffness of the asphalt concrete is represented by the complex modulus $E^*$, which is very important properties in the mechanistic design of flexible pavement system. The moduli of asphalt concrete were generally determined by dynamic modulus test. However, the dynamic modulus testing method is too complex, expensive, and time consuming to be applicable on a production basis. The IR(Impact Resonance) method has been shown to be a truly simple nondestructive testing method which produces very repetitive, consistent results. The major object of this study was to estimate of the effects on IR tests for determining modulus of asphalt concrete including impact position, specimen support condition, impact steel ball size and sampling rate. The variations of IR test results with various testing conditions are within ${\pm}2.7%$.

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A Study on the Detection of Defects from Parallel Cylindrical Objects Using Spectral Analysis of Acoustic Impact Signal (타격음 주파수 분석법에 의한 원통 병렬 구조물의 파손 여부 식별에 관한 연구)

  • Bang, Ho-Gyun;Jo, Cheol-U
    • The Journal of the Acoustical Society of Korea
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    • v.14 no.4
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    • pp.12-20
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    • 1995
  • This paper describes principles and experimental results in conjunction with examining the possibility of the detection of effects from a cylindrical objects. Cylindrical objects have its own resonance frequency. The frequency varies according to the diameter, length etc. And acoustic sound, whose frequency and the harmonic components corresponding to resonance frequency, is radiated from the object. When an object have defect in itself, the radiated acoustic sound is different from normal one. So we can detect its defect by analysing frequency components of acoustic sound. We proved that detection of defective objects by acoustic signal analysis is possible automatically. Also the result can be applied to other kinds of objects.

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Analysis of Vibration Modes of Small and Large Concrete Blocks Containing Flaws by Impact Resonance Method (충격 공진법에 의한 대소 경계조건하 콘크리트 블록 내부결함 신호의 해석)

  • Park, Seok-Kyun;Yoon, Seok-Soo
    • Magazine of the Korea Concrete Institute
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    • v.11 no.1
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    • pp.161-171
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    • 1999
  • Impact resonance testing was carried out on small and large concrete blocks containing several types of artificial flaws respectively. Quantitative analysis of the observed peak frequencies in the impact resonance tests identifies the possible normal modes of concrete blocks containing flaws. and enables to determine the depth and size of the flaws in concrete blocks. In this study, concrete can be treated as a homogeneous and isotropic material. The flaw size and location at each section of artificial flaw series in small and large concrete blocks, determined through two-dimensional scanning of impact point and real-time fast Fourier transform, are in good agreement with real size location, respectively. Consequently, quantitative analysis method of vibration modes in the impact resonance tests, which can be applied for homogeneous and isotropic material, can be useful for the detection of flaws in any case of small and large concrete blocks in this study.

Application of Impact Echo Method to Civil Engineering Fields (토목공학 분야에서의 충격반향법의 응용)

  • Jung, Yun-Moon;Ha, Hee-Sang
    • Geophysics and Geophysical Exploration
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    • v.3 no.3
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    • pp.94-100
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    • 2000
  • Many nondestructive test methods used for metallic materials have some limit in application to concrete materials due to their heterogeneity. Impact echo method utilizes the resonance frequency of reflected seismic waves from defects or the boundary between two materials and can be applied to investigate the interior of concrete structures. In this study, a field data acquisition system for the impact echo method was assembled and field tests under various conditions were performed. The impact echo method was applied for investigating thickness/defects/backfilling of concrete structures/tunnel lining/airport pavement. The applicability of the impact echo method to the civil engineering field was substantiated by providing results within $10\%$ errors.

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Investigation on Impact-echo Testing Method for Rock Specimens (암석 시편의 충격반향(공진주) 시험에 관한 고찰)

  • Cho, Jung-Woo;Lim, Bo-Sung;Cho, Ho-Bum;Jeon, Seok-Won;Ha, Hee-Sang
    • Tunnel and Underground Space
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    • v.17 no.2 s.67
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    • pp.83-89
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    • 2007
  • Impact-echo test is a non-destructive testing method to determine dynamic properties of a material. This presentation introduces the experimental set-up and procedure of the test for rock specimens. In addition, the test results of domestic rocks collected in 5 different areas, a cement mortar and aluminium alloy are presented. The test results include resonance frequencies of P- and S-wave as well as damping ratios of the described 7 different materials. The differences between dynamic and static values of elastic moduli are about 10%, while the dynamic Poisson's ratios are greater than the static Poisson's ratios by at least 0.07. The damping ratio is dependent on the joint density and degree of weathering of a rock specimen.

Reliability Evaluation for Prediction of Concrete Compressive Strength through Impact Resonance Method and Ultra Pulse Velocity Method (충격공진법과 초음파속도법을 통한 콘크리트 압축강도 예측의 신뢰성 평가)

  • Lee, Han-Kyul;Lee, Byung-Jae;Oh, Kwang-Chin;Kim, Yun-Yong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.19 no.4
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    • pp.18-24
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    • 2015
  • Non-destructive testing (NDT) methods are widely used in the construction industry to diagnose the defects/strength of the concrete structure. However, it has been reported that the results obtained from NDT are having low reliability. In order to resolve this issue, four kinds of NDT test (ultrasonic velocity measurements by P-wave and S-wave and the impact resonance methods by longitudinal vibration and deformation vibration) were carried out on 180 concrete cylinders made with two kinds of mix proportions. The reliability of the NDT results was analyzed and compared through the measurement of the actual compressive strength of the concrete cylinders. The statistical analysis of the results was revealed that the ultrasonic velocity method by S-wave is having lowest coefficient of variation and also most capable of stable observation. Analytical equations were established to estimate the compressive strength of the concrete from the obtained NDT results by relating the actual compressive strength. Moreover the equation established by the ultrasonic velocity method by S-wave had the highest coefficient of determination. Further studies on the stability of non-destructive testing depending on various mixing conditions will be necessary in the future.