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Proceedings Paper

Nondestructive evaluation of piers
Author(s): Ionica Negru; Gilbert-Rainer Gillich; Zeno-Iosif Praisach; Marius Tufoi; Edwald-Viktor Gillich
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Paper Abstract

This paper proposes a vibration-based damage detection method designed for structural elements subjected to important vertical loads, as columns or pillars. The method is based on the relation existing between the energy stored in the pillar in several vibration modes and the corresponding natural frequencies. For a certain mode, this energy results as the sum of the energies stored in all pillar slices, being dependent on the rigidity and the squared of the corresponding mode shape curvature. This means that the energy distribution along the pillar is different for each mode. Thus, reducing the rigidity of one slice due to damage, the frequencies will decrease in different ways, depending on the slice location. This fact permits to contrive patterns able to characterize the effect of damage at any location along the pillar. Since the mode shapes (and the natural frequencies) are influenced by inertial forces, but in the meantime by the compression and shear forces induced by the top mass, the patterns have to be derived for each load case. The paper presents a simple mathematical expression able to predict frequency changes if damage occurs at any location along the pillar and for any top mass value. Patterns that characterize the damage location are consequently derived by using the squared mode shape curvatures of the healthy beam. The damage location becomes an inverse problem, it being found by interpreting the results of frequency measurements for the healthy and damaged state. The process of damage location is exemplified by numerical simulations.

Paper Details

Date Published: 23 March 2015
PDF: 10 pages
Proc. SPIE 9438, Health Monitoring of Structural and Biological Systems 2015, 943817 (23 March 2015); doi: 10.1117/12.2081432
Show Author Affiliations
Ionica Negru, Univ. "Eftimie Murgu" of Resita (Romania)
Gilbert-Rainer Gillich, Univ. "Eftimie Murgu" of Resita (Romania)
Zeno-Iosif Praisach, Univ. "Eftimie Murgu" of Resita (Romania)
Marius Tufoi, Univ. "Eftimie Murgu" Resita (Romania)
Edwald-Viktor Gillich, Politehnica Univ. of Timisoara (Romania)

Published in SPIE Proceedings Vol. 9438:
Health Monitoring of Structural and Biological Systems 2015
Tribikram Kundu, Editor(s)

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