Identification of Stiffness Reductions Using Natural Frequencies

Hassiotis, Sophia; Jeong, Garrett D.

doi:10.1061/(asce)0733-9399(1995)121:10(1106)

Cited by 133 publications

(49 citation statements)

References 20 publications

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“…However, the former issue was addressed here only partially (a deeper investigation would have required performing more sophisticated nonlinear analyses), whereas the latter was not addressed at all, it being beyond the scope of the present study. On the other hand, much literature on the evaluation of crack location and depth based on measured natural frequencies (and modes) exists (e.g., see [43][44][45][46][47][48][49][50][51][52]). This work represents a first attempt to correlate AE signals produced by material damage with variations in the natural vibration frequencies of a cracking element.…”

Section: Discussionmentioning

confidence: 99%

Acoustic Emission and Modal Frequency Variation in Concrete Specimens under Four-Point Bending

2017

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Abstract:The Acoustic Emission (AE) and Dynamic Identification (DI) techniques were applied simultaneously, in an original way, to examine the stress dependent damage progress in pre-notched concrete beams tested in four-point bending. The damage mechanisms were characterized by analyzing the AE signals registered during the tests, conducted by increasing the specimen's vertical deflection. In particular, the dominant fracture mode was identified, and correlations between dissipated and emitted energies were investigated. Moreover, variations in the natural bending frequencies, produced by the crack advancement under loading, were detected and put in relation with the cumulated AE energy. Two different types of piezoelectric (PZT) sensors, operating in well distinct frequency ranges, were used to measure AE and modal signals. This study may be of interest with an outlook on possible correlations between a multi-parameter structural monitoring and the solution of inverse problems by numerical models.

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Section: Discussionmentioning

confidence: 99%

Acoustic Emission and Modal Frequency Variation in Concrete Specimens under Four-Point Bending

2017

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“…For illustration, the aluminium cantilever beam studied in [16] is taken under consideration herein based on the developed above theory. Initial model parameters and measurement data of the beam are as follow: the length L = 495.3 mm, wide W = 25.4 mm, thick H = 6.35 mm, Young's.modulus E = 7.l · 10 7 kPa, mass density p = 2210 kg/ m 3 .…”

Section: Numerical Case Studymentioning

confidence: 99%

“…In the our paper [15] the frequency equation of damaged beam has been established in general form for all of the classical boundary conditions, that is likely the equation given by Liang. In this paper the general frequency equation of damaged beams obtained in [15] will be developed for elastic end supports since, as shown in reference [16], the idealisation of the boundary conditions can lead to significant shift of natural frequencies .…”

Section: Introductionmentioning

confidence: 99%

Damage detection of beam by natural frequencies: General theory and procedure

Khiem¹

2006

Vietnam J. Mech.

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Abstract. The frequency equation of single damaged beam has been established for arbitrary boundary conditions that is the main tool for analysis as well as identification of damaged beam by using measured natural frequencies. A procedure for damage detection problem presented in this paper consists of three steps. First, the modelling error is reduced by a model updating procedure, in which the material, geometrical parameters and boundary conditions are updated. Then , measurement data are corrected based on t he updated model. Finally, the damage parameters are identified using updated model and corrected measurement data. Theoretical investigation is illustrated by an example.

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“…Hence, the deterioration can be estimated using sensors mounted at any position on a structure. In particular, the changes in the natural frequency have been thoroughly investigated as identifiers of stiffness reduction [2]. In addition, the changes in the uncertain frequency, mode shape data [3], incomplete mode shape [4], mode shape curvatures [5], and flexibility matrix [6] were used to localize the damage.…”

Section: Introductionmentioning

confidence: 99%

“…Over the years, many studies have been performed on the application of dynamic responses and damage detection [1][2][3][4][5][6][7] in terms of the natural frequencies, mode shapes, modal curvature, and high-order mode shape derivative. A recent study demonstrated that natural frequencies, mode shapes, and damping ratios are invariant in structures [1].…”

Section: Introductionmentioning

confidence: 99%

Long-Term Vibration Monitoring of the Effects of Temperature and Humidity on PC Girders with and without Fly Ash considering ASR Deterioration

Fukada

Torii

2017

Shock and Vibration

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Structural responses have been used as inputs in the evaluation procedures of civil structures for years. Apart from the degradation of a structure itself, changes in the environmental conditions affect its characteristics. For adequate maintenance, it is necessary to quantify the environment-induced changes and discriminate them from the effects due to damage. This study investigates the variation in the vibration responses of prestressed concrete (PC) girders, which were deteriorated because of the alkali-silica reaction (ASR), concerning ambient temperature and humidity. Three PC girders were exposed to outdoor weather conditions outside the laboratory, one of which had a selected amount of fly ash in its mixture to mitigate the ASR. The girders were periodically vibration tested for one and a half years. It was found that when the temperature and humidity increased, the frequencies and damping ratios decreased in proportion. No apparent variation in the mode shapes could be identified. A finite element model was proposed for numerical verification, the results of which were in good agreement with the measured changes in the natural frequencies. Moreover, the different dynamic performances of the three specimens indicated that the fly ash significantly affected the vibrations of the PC girders under ASR deterioration.

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Identification of Stiffness Reductions Using Natural Frequencies

Cited by 133 publications

References 20 publications

Acoustic Emission and Modal Frequency Variation in Concrete Specimens under Four-Point Bending

Acoustic Emission and Modal Frequency Variation in Concrete Specimens under Four-Point Bending

Damage detection of beam by natural frequencies: General theory and procedure

Long-Term Vibration Monitoring of the Effects of Temperature and Humidity on PC Girders with and without Fly Ash considering ASR Deterioration

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