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.
References
Abrams, D. A. (1913). “Tests of bond between concrete and steel.” Bulletin No. 71, Engineering Experiment Station, Univ. of Illinois, Urbana, Ill.
Alvarez, M. (1998). “Einfluss des Verbundverhaltens auf das Verformungsvermögen von Stahlbeton [Influence of bond behavior on the deformation capacity of structural concrete].” IBK Rep. No. 236, Institute of Structural Engineering, ETH, Zurich (in German).
Bertholds, A., and Dändliker, R. (1988). “Determination of the individual strain-optic coefficients in single-mode optical fibers.” J. Lightwave Technol., 6(1), 17–20.
Comité Euro-International du Béton (CEB-FIP). (1993). Model code for concrete structures, Lausanne, Switzerland.
Chen, W. F. (1970). “Double punch test for tensile strength of concrete.” ACI J., 67(12), 993–995.
Fédération Internationale du Béton. (2000). “Bond of reinforcement in concrete.” Bulletin 10: State-of-the-Art Rep., Lausanne, Switzerland.
Froggatt, M., and Moore, J. (1998). “Distributed measurement of static strain in an optical fiber with multiple Bragg gratings at nominally equal wavelengths.” Appl. Opt., 37(10), 1741–1746.
Hill, K. O. , and Meltz, G. (1997). “Fiber Bragg grating technology fundamentals and overview.” J. Lightwave Technol., 15(8), 1265–1276.
Kenel, A. (2002). “Biegetragverhalten und Mindestbewehrung von Stahlbetonbauteilen [Flexural behavior and minimum reinforcement of structural concrete members].” IBK Rep. No. 277, Institute of Structural Engineering, ETH, Zurich (in German).
Kenel, A., and Marti, P. (2002). “Faseroptische Dehnungsmessungen an einbetonierten Bewehrungsstäben [Fiber-optic steel strain measurements on embedded reinforcing bars].” IBK Rep. No. 271, Institute of Structural Engineering, ETH, Zurich (in German).
Kuuskoski, V. (1950). “Über die Haftung zwischen Beton und Stahl [On the adhesion between concrete and steel].” PhD thesis, Technical Univ. of Finland, Helsinki, Finland (in German).
Lahnert, B. J. , Houde, J., and Gerstle, K. H. (1986). “Direct measurement of slip between steel and concrete.” ACI J., 83(6), 974–982.
Mains, R. M. (1951). “Measurement of the distribution of tensile and bond stresses along reinforcing bars.” ACI J., 48(3), 225–252.
Marti, P. (1989). “Size effect in double punch tests on concrete cylinders.” ACI Mater. J., 86(6), 597–601.
Marti, P. (2001). “Stahlbeton Grundzüge [Structural concrete fundamentals].” Lecture Notes, Institute of Structural Engineering, ETH, Zurich (in German).
Marti, P., Alvarez, M., Kaufmann, W., and Sigrist, V. (1998). “Tension chord model for structural concrete.” Struct. Eng. Int. (IABSE, Zurich, Switzerland) 8(4), 287–298.
Mohr, O. (1868). “Beiträge zur Theorie der Holz - und Eisenkonstruktionen. Behandlung der elastischen Linie als Seillinie; zeichnerische Untersuchung des elastischen Balkens [Contributions to the theory of timber and steel structures. Treating the deflection curve as a funicular polygon; graphical analysis of the elastic beam].” Zeitschrift des Architekten- und Ingenieur-Vereins zu Hannover, 14, 19–51 (in German).
Rehm, G. (1961). “Über die Grundlagen des Verbundes zwischen Stahl und Beton [On the bases of bond between steel and concrete].” Deutscher Ausschuss für Stahlbeton, 138 (in German).
Sennhauser, U., and Nellen, P. M. (2000). “Reliability of fiber optic sensors.” Trends in optical non-destructive testing and inspections, P. Rastogi and D. Inaudi, eds., Elsevier, New York, 473–485.
Shima, H., Chou, L.-L., and Okamura, H. (1987). “Micro and macro models for bond in reinforced concrete.” J. Fac. Eng., Univ. Tokyo, 39(2), 133–194.
Sigrist, V. (1995). “Zum Verformungsvermögen von Stahlbetonträgern [On the deformation capacity of structural concrete beams].” IBK Rep. No. 210, Institute of Structural Engineering, ETH, Zurich (in German).
Sirkis, J. S. (1993). “Unified approach to phase-strain-temperature models for smart structure interferometric optical fiber sensors. Part 1: Development; Part 2: Applications.” Opt. Eng. (Bellingham), 32(4), 752–772.
Watstein, D. (1947). “Distribution of bond stress in concrete in pull-out specimens.” ACI J., 44(5), 1041–1052.
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© 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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