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Proceedings Paper

Use of laser techniques for detecting modal shifts in damaged concrete intake tower models
Author(s): Richard C. Dove; Mostafiz R. Chowdhury
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Paper Abstract

In the event of an earthquake, it is vitally important that the catastrophic failure of a dam and subsequent sudden release of the reservoir be prevented. An important part of the prevention of such a failure is maintaining the ability to control the release of water after the earthquake. For the most earthen dams, and some concrete dams, the release of water is controlled through a reinforced concrete intake tower. Most intake towers in the US Army Corps of Engineers existing inventory are very lightly reinforced. The functional survival of such lightly reinforced towers was the main concern of a recent research effort conducted at the US Army Engineer Waterways Experiment Station. The ultimate objective of this research was the evaluation and/or development of approximate or simplified analysis procedures for the evaluation of the ductility of existing intake towers. As part of this research, a series of three experiments were conducted, each of which was composed of the static loading to failure of 1/8th scale models of a typical intake tower configuration. Experimental results for two models are reported in this paper. Cyclic bending loads were applied to the models.Material properties and the percentage of steel were varied to model extremes encountered in existing towers. Modal surveys of the experiment models before, during, and after experimentation were conducted using a Scanning Laser Doppler Vibrometer system. These surveys were used to quantify the changes in the mode shapes and frequencies due to the damage accumulated during experimentation. The application of laser vibrometry and modal analysis to this problem is the main focus of this paper.

Paper Details

Date Published: 1 June 1998
PDF: 9 pages
Proc. SPIE 3411, Third International Conference on Vibration Measurements by Laser Techniques: Advances and Applications, (1 June 1998); doi: 10.1117/12.307712
Show Author Affiliations
Richard C. Dove, U.S. Army Engineer Waterways Experiment Station (United States)
Mostafiz R. Chowdhury, U.S. Army Engineer Waterways Experiment Station (United States)

Published in SPIE Proceedings Vol. 3411:
Third International Conference on Vibration Measurements by Laser Techniques: Advances and Applications
Enrico Primo Tomasini, Editor(s)

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