Reinforced Concrete Beams Analyzed with Rayleigh Fibre Optic Strain Sensing

A vast amount of North America’s reinforced concrete infrastructure is deteriorating and reaching the end if its design life. One potential way to extend the service life of these structures is to use structural health monitoring (SHM) technologies to better assess the effects of deterioration. Fibre optic sensors (FOS) using rayleigh optical backscatter reflectometry offer the unique capability to measure strain along the whole fibre over small gauge lengths potentially with microstrain resolution. These systems could be used to provide critical insight into deterioration mechanisms. However, before these systems can be used in SHM applications, installation techniques need to be developed and measurement accuracy confirmed. In this study, reinforced concrete beams instrumented with both conventional strain gauges and FOS were tested. A number of fibre optic installation methods were evaluated (e.g. internally tied and bonded fibres and externally epoxied fibres) to determine which provided the most accurate results. The accuracy of the FOS measurements was found to be a function of the type of bonding used although excellent correlation with strain gauge results was found in some cases. Further work is required to determine whether the FOS can be used to accurately locate and quantify localized steel deterioration in reinforced concrete structures.

1. Bentz, E.C. “Sectional analysis of reinforced concrete members,” Ph.D. thesis, Dept. of Civil Engineering, University of Toronto, Toronto. 2000. 2. Graybeal, B.A., B.M. Phares, D.D. Rolander, M. Moore and G. Washer. “Visual inspection of highway bridges,” Journal of Nondestructive Evaluation, Vol. 21, No. 3, p 67-83. 2003. 3. Gebremichael, Y.M., W. Li, B.T. Meggitt, W.J.O. Boyle, K.T.V. Grattan, B. McKinley, L.F. Boswell, K.A. Aarnes, S.E. Aasen, B. Tynes, Y. Fonjallaz and T. Triantafillou. “A Field Deployable, Multiplexed Bragg Grating Sensor System Used in an Extensive Highway Bridge Monitoring Evaluation Tests,” IEEE Sensors Journal, Vol. 5, No. 3, 510-519. 2005. 4. Guemes, A., A. Fernandez-Lopez and B. Soller. “Optical Fiber Distributed Sensing – Physical Principles and Applications,” Polytechnic University of Madrid and LUNA Technologies, Vol 9, No.3: 233-13. 2010. 5. Henault, J.M., J. Salin, G. Moreau, S. Delepine-Lesoille, J. Bertand, F. Taillade, M. Quiertant and K. Benzarti. “Qualification of a Truly Distributed Fibre Optic Technique for Strain and Temperature Measurements in Concrete Structures,” EPJ Web of Conferences, Vol. 12. 2011. 6. Indaudi, D., S. Vurpillot, N. Casanova, A. Osa-Wyser. “Development and field test of deformation sensors for concrete embedding,” SPIE Journal, Vol 2721, p 138-148. 1996. 7. Mohamad, H., K. Soga, A. Pellew and P.J. Bennett. “Performance monitoring of a secant-piled wall using distributed fiber optic strain sensing,” Journal of Geotechnical and Geoenvironmental Engineering, Vol. 137, No. 12, 1236-1243. 2011. 8. Soller, B.J., M. Wolfe and M.E. Froggatt. “Polarization resolved measurement of Rayleigh backscatter in fiberoptic components,” OFC Technical Digest, Los Angeles. 2005. 9. Lanticq, V., R. Gabet, F. Taillade and S. Delepine-Lesoille. Distributed Optical Fibre Sensors for Structural Health Monitoring: Upcoming Challenges, Optical Fiber New Developments, Christophe Lethien (ed.), ISBN: 978-953-7619-50-3. 2009.
Usage Shares
Total Views
17 Page Views
Total Shares
0 Tweets
0 PDF Downloads
0 Facebook Shares
Total Usage