Reinforcing Steel Strains Measured by Bragg Grating Sensors
Publication: Journal of Materials in Civil Engineering
Volume 17, Issue 4
Abstract
Steel strain measurements along reinforcing bars allow an indirect determination of bond shear stresses acting between concrete and reinforcement. Traditional measuring techniques such as the application of electrical resistance strain gauges are not entirely satisfactory because they affect the bond properties. This paper describes experiments using wavelength multiplexed optical fiber Bragg grating sensors for strain measurements along 10-mm-diameter reinforcing bars embedded in reinforced concrete beams subjected to bending. The sensors were found to be capable of measuring large strains and strain gradients with high precision, without significantly affecting the bond properties. The experimental results are discussed and compared with calculations according to three bond shear stress-slip models. Recommendations for the application of optical fiber Bragg grating sensors on reinforcing bars are made and a simple method for the deflection calculation of partially cracked beams is presented, providing lower und upper bounds corresponding to maximum and minimum theoretical crack spacings, respectively.
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Acknowledgments
Financial support from the Swiss National Science Foundation, the Swiss Federal Highway Administration, and the Association of Swiss Cement Producers is gratefully acknowledged. The writers are indebted to M. Froggatt, NASA Langley Research, for providing the high quality Bragg gratings.
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Information & Authors
Information
Published In
Journal of Materials in Civil Engineering
Volume 17 • Issue 4 • August 2005
Pages: 423 - 431
Copyright
© 2005 ASCE.
History
Received: Dec 3, 2003
Accepted: May 20, 2004
Published online: Aug 1, 2005
Published in print: Aug 2005
Notes
Note. Associate Editor: John S. Popovics
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