This article describes proof-of-concept testing of a sensor based on magnetic field detection to estimate the remaining effective cross-sectional area in corroded prestressing strands inside prestressed concrete beams. The primary corrosion mode is rusting of the strand. The magnetic properties of rust are vastly different from those of steel, thus making a magnetic sensor theoretically feasible. An electromagnet system with Hall sensors has been designed. The electromagnet induces a magnetic field in the specimen by magnetizing it from one side, and at a particular distance from the electromagnet’s pole face. At near magnetic saturation, for various diameters and distances of up to 2 in from the magnet face, the induced magnetic field is reliably related to the effective cross-section of the steel bar. Experiments with steel rods and prestressing strands of different diameters conducted in a laboratory are presented. Initial results confirm that by using an appropriate electromagnet based on the magnetic-field technique, in-situ detection of remaining effective cross-sectional area is possible. Challenges in making this technique practical are discussed. If the follow-up research confirms the practicality of the proposed magnetic sensor, there is a potential to substantially improve the state-of-the-art in bridge inspection in terms of accuracy and convenience.
1. NACE International. White Papers: Bridge Corrosion. Available at: http://www.nace.org/content.cfm?parentid=1046¤tID=1421. Last accessed 11 November, 2010.
2. C. M. Scott. Non-Composite Adjacent Box Beam Bridges. A presentation adapted from AASHTO T-18 Bridge Inspection Technical Committee Meeting. Orlando, FL, pp. 3–9, June 2006.
3. E. Steinberg. Structural Evaluation of LIC-310-0396 Box Beams with Advanced Strand Deterioration, Ohio Department of Transportation. Research in progress, Contract=Grant Number: 134381 (since May 2008).
4. K. A. Harries. Full-Scale Testing Program on De-commissioned Girders from the Lake View Drive Bridge. PITT Report CE=ST-33 or FHWA-PA-2006-008-EMG001, Pennsylvania Department of Transportation, August 2006.
5. L. Jones, S. Pessiki, C. Naito, and I. Hodgson. Inspection methods and techniques to determine nonvisible corrosion of prestressing strands in concrete bridge components. Task 2–-Assessment of candidate NDT methods. Lehigh University, ATLSS Report No. 09-09, June 2010.
6. C. Abi Shdid and M. H. Ansley. Transportation Research Record: Journal of the Transportation Research Board 1975:3–9 (2006).
7. Ohio Department of Transportation (ODOT). Structural Evaluation of LIC-310-0396 Box Beams with Advanced Strand Deterioration. Request for Proposals PS-08-11. (2008).
8. Federal Highway Administration (FHWA). Structure Type by State as of Dec. 2009. http://www.fhwa. dot.gov/bridge/nbi/strtyp09.cfm (last accessed 11 November, 2011).
9. American Association of State Highway and Transportation Officials. The Manual for Bridge Evaluation. Second edition. Washington, D.C. (2011).
10. H. Scheel and B. Hillemeier. NDT&E International 30(4):211–216 (1997).
11. C. Naito and L. Jones. Nondestructive Inspection of Strand Corrosion in Prestressed Concrete Box Beam Members. NDE=NDT for Highways and Bridges: Structural Materials Technology Conference, New York City (2010).
12. A.T. Ciolko and H. Tabatabai. Nondestructive Methods for Condition Evaluation of Prestressing Steel Strands in Concrete Bridges Final Report: Phase I–Technology Review. NCHRP Web Document 23 (Project 10–53). Transportation Research Board (1999).
13. D. K. Nims and N. Grace. Evaluation of Stay-in-Place Metal Forms. Final Report FHWA/OH–2006/Ohio Department of Transportation, Office of Research and Development, Columbus, OH (2006).
14. L. Chen, P.W. Que, and T. Jin. Russian Journal of Nondestructive Testing, 41(7):462–465 (2005).
15. O. Mihalache, G. Preda, N. Yusa, and K. Miya. Experimental Measurements and Numerical Simulation of OD and ID in Plate Ferromagnetic Materials Using Magnetic Flux Leakage. Energy and Information in Non-Linear Systems, Proceedings of the 4th Japan–Europe Joint Workshop, Brno, Czech Republic, pp. 106–109 (November 2000).
16. F. N. Kusenberger and J. R. Barton. Detection of Flaws in Reinforcement Steels in Prestressed Concrete Bridges. Final Report FH-WA=RD-81=087, Federal Highway Administration (FHWA), Washington, D.C. (1981).
17. C. U. Grosse (Ed.). In Advances in Construction Materials 2007, pp. 639–649 (2007). Springer, Berlin, Germany.
18. A. Ghorbanpoor, R. Borchelt, M. Edwards, and E. Abdel Salam. Magnetic-Based NDE of Prestressed and Post-Tensioned Concrete Members-–The MFL System. Final Report FHWA-RD-00–026, Federal Highway Administration, U.S. Department of Transportation, McLean, VA (2000).
19. M. DaSilva, S. Javidi, A. Yakel, and A. Azizinamini. Nondestructive Method to Detect Corrosion of Steel Elements in Concrete. Final Report NDOR Research Project No. P597. National Bridge Research Organization (NBRO) (2009).
20. B. Hillemeier and H. Scheel. Materials and Corrosion 49(11):799–804 (1998).
21. H. Scheel, and B. Hillemeier. Journal of Materials in Civil Engineering ASCE 15(3) 228–234 (2003).
22. J. W. Wilson, G. Y. Tian, and S. Barrans. Sensors and Actuators A: Physical 135(2):381–387 (2007).
23. H. R. Weischedel. Method and apparatus for magnetically inspecting elongated objects for structural defects. U.S. Patent 4,659,991, filed March 31, 1983, and issued April 21, 1987.
24. F. Kitzinger and G. A. Windt. Magnetic testing device for detecting loss of metallic area and internal and external defects in elongated objects. U.S. Patent 4,096,437, filed September 30, 1976 and issued June 20, 1978.
25. W. Trautmann. Apparatus for the nondestructive testing of elongated test specimens by magnetic techniques. U.S. Patent 4,519,243, filed March 10, 1983 and issued May 28, 1985.
26. F. Rumiche, J. E. Indacochea, and M. L. Wang. Journal of Engineering Materials and Technology, 130(3):031008 (2008).
27. J. Makar and R. Desnoyers. NDT&E International 34(7):445–456 (2001).
28. Ohio Department of Transportation (ODOT). Design Data: Prestressed Concrete Non-Composite Adjacent Box Beams (48’’ Wide) with Straight Strands. Drawing PSBDD-2–07, pp. 1 (2002).
29. Ohio Department of Transportation (ODOT). Design Data for Prestressed Concrete Bridge 24 ft. Roadway Width Non-Composite 4800 Adjacent Box Beams with Straight Strands, pp. 1 (1981).
14 Page Views
0 PDF Downloads
0 Facebook Shares