To develop a simple method for detecting and monitoring FRP-concrete debonding with the use of distributed Brillouinbased fiber optic strain sensor, this study proposes a model that takes into consideration both the steady and the transient Brillouin interaction states. Assuming that the transient term has an analogous effect on the steady state term, two parameters, the effective transient length and the intensity reduction ratio, are introduced. The proposed model shows that the stimulated Brillouin signal intensity distribution at the specific frequency, which corresponds to the maximum strain at the debonded region, is sensitive to the occurrence of debonding. For evaluation of the model, experiments are carried out on a reinforced concrete beam retrofitted with glass FRP sheets on which sensing fibers are mounted, and the results agree with the observation. This numerical and experimental study demonstrates the effectiveness of the proposed model that incorporates not only the steady Brillouin interaction state. The model enables debonding detection without baseline measurement, leveraging the stimulated Brillouin scattering principle with high spatial resolution and high accuracy.

Date Published: 8 April 2009
PDF: 10 pages
Proc. SPIE 7294, Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2009, 72940N (8 April 2009); doi: 10.1117/12.816603

Published in SPIE Proceedings Vol. 7294:
Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2009
H. Felix Wu; Aaron A. Diaz; Peter J. Shull; Dietmar W. Vogel, Editor(s)