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Sharma FINAL 7 30 2020 with cert.pdf (1.84 MB)

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Damage Detection in a Steel Beam using Vibration Response

Sharma, Utshree
http://rave.ohiolink.edu/etdc/view?acc_num=ysu1596222984454508

Abstract Details

2020, Master of Science in Engineering, Youngstown State University, Department of Civil/Environmental and Chemical Engineering.
In any civil engineering structure, damage resulted from the construction phase or developed over time affects the structural performance and may result in its failure. Early-stage damage detection is necessary for maintaining structural safety, serviceability, and minimizing the cost throughout the structural operation. Various destructive and conventional non-destructive damage detection techniques employed over the years are either laborious or, uneconomical, and require access to the entire structure. These limitations were addressed by developing the vibration-based methods for regular structural health monitoring. This holistic approach includes analyses of vibration signals and the related modal parameters. The change in these parameters may be used for detection of damage. In this research, modal frequency was used as a parameter to detect damage. The objective is to identify damage using natural frequency. To achieve this objective, several tests were conducted on simply supported steel beams having an open transverse crack with varying depths and locations. The analytical, numerical, and experimental approaches generate frequencies for the first three vibrating modes. The analytical approach considered the beam as the Euler-Bernoulli beam. Analytical frequencies were found from the solution of a partial differential equation by applying the boundary conditions. Vibration signals collected from the portable digital vibrometer (PDV 100) were analyzed using the Fast Fourier Transform (FFT) technique to achieve modal frequencies of the steel beam. In ANSYS (ANSYS, 2017), the finite element models of the beams were calibrated using the experimental results. The frequency from the analytical approach depends on the crack depth. Therefore, this method cannot produce the actual frequency of a beam with varying damage locations and depths. The graphical plots of the normalized frequency with varying damage depth and damage location was used to study the impact of damage location and depth of damage on the frequency. These plots from the experimental study and ANSYS showed similar pattern for the first mode of vibration. With an increase in the size of a crack, the natural frequency of a beam decreases. It also decreases as the location of the crack moves away from the support. At the location of maximum bending moment, the lowest natural frequency was recorded. The nodal points were identified as the locations where the damaged frequency equals the frequency of an intact beam. These points were detected for the second and the third modes of vibration. The existence of damage in the beam specimen was confirmed by comparing the natural frequency of a beam at its intact and damaged stage. Equations relating normalized frequency with varying crack depth and location were established from the experimental natural frequency. These equations can be used for crack detection in a beam using its natural frequency. Thus, a damage detection technique using natural frequency has been demonstrated and proposed in this research. The frequency of a beam is related to depth of crack, location of crack, and its modal properties. In future, this study can be extended to the beams with various damage configurations, boundary conditions, material properties, and multiple cracks with varying depth and location. The effectiveness of this method on a bridge vibrating under vehicular loads will be an interesting investigation indeed.
AKM Anwarul Islam, PhD (Advisor)
Shakir Husain, PhD (Committee Member)
Richard Deschenes, PhD (Committee Member)
69 p.
Civil Engineering; Engineering
Damage Detection; Steel Beam; Natural Frequency; Euler-Bernoulli Beam; PDV 100; FFT; ANSYS

Recommended Citations

Citations

  • Sharma, U. (2020). Damage Detection in a Steel Beam using Vibration Response [Master's thesis, Youngstown State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1596222984454508

    APA Style (7th edition)

  • Sharma, Utshree. Damage Detection in a Steel Beam using Vibration Response. 2020. Youngstown State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ysu1596222984454508.

    MLA Style (8th edition)

  • Sharma, Utshree. "Damage Detection in a Steel Beam using Vibration Response." Master's thesis, Youngstown State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1596222984454508

    Chicago Manual of Style (17th edition)

ysu1596222984454508
886
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This open access ETD is published by Youngstown State University and OhioLINK.