A nondestructive evaluation (NDE) technique for monitoring damage due to crack growth in concrete beams is presented in this paper. The technique is based on monitoring the resonant frequencies of vibration. An introduction to the concepts of vibrational modes in beams is detailed first followed by a description of the experimental procedure for resonance frequency measurement. The results of a finite element (FE) analysis that is performed to identify the different modes of vibration of the beam specimen, are then presented. The resonance frequencies determined by the FE analysis are shown to match closely with the experimental values. A notch is introduced in the specimen and the effect of notch length on the resonant frequencies is studied by varying the notch depth. Experimental results are compared with the results of FE simulation of the beam with different notch lengths. The influence of a real crack on the frequencies of the vibrational modes is also studied by loading a specimen in a three-point bending configuration and propagating a crack in a controlled manner using a closed-loop testing machine. Analysis of the obtained data is performed to evaluate the response of the different vibrational modes of the concrete beam specimen to varying crack and notch lengths. Frequencies of the vibrational modes decrease consistently with increasing crack and notch lengths. There is a larger decrease associated with increasing notch length. Resonance frequencies are shown to be sensitive to crack and notch growth in concrete beams and can be used to effectively monitor the decrease in structural stiffness due to crack progress progression.
|Original language||English (US)|
|Number of pages||8|
|Journal||Proceedings of SPIE - The International Society for Optical Engineering|
|State||Published - Jan 1 1999|
ASJC Scopus subject areas
- Electrical and Electronic Engineering
- Condensed Matter Physics