Structural Engineering and Mechanics

Techno-Press (테크노프레스)
권호 표지
DOI QR코드

DOI QR Code

Detection of tension force reduction in a post-tensioning tendon using pulsed-eddy-current measurement

  • Kim, Ji-Min (Department of Civil Engineering, Korean Advanced Institute for Science and Technology) ;
  • Lee, Jun (Department of Civil Engineering, Korean Advanced Institute for Science and Technology) ;
  • Sohn, Hoon (Department of Civil Engineering, Korean Advanced Institute for Science and Technology)
  • Received : 2017.12.15
  • Accepted : 2017.12.18
  • Published : 2018.01.25
⟨ Previous Next ⟩

Abstract

Post-tensioning (PT) tendons are commonly used for the assembly of modularized concrete members, and tension is applied to the tendons during construction to facilitate the integrated behavior of the members. However, the tension in a PT tendon decreases over time due to steel corrosion and concrete creep, and consequently, the stress on the anchor head that secures the PT tendon also diminishes. This study proposes an automatic detection system to identify tension reduction in a PT tendon using pulsed-eddy-current (PEC) measurement. An eddy-current sensor is installed on the surface of the steel anchor head. The sensor creates a pulsed excitation to the driving coil and measures the resulting PEC response using the pick-up coil. The basic premise is that the tension reduction of a PT tendon results in stress reduction on the anchor head surface and a change in the PEC intensity measured by the pick-up coil. Thus, PEC measurement is used to detect the reduction of the anchor head stress and consequently the reduction of the PT tendon force below a certain threshold value. The advantages of the proposed PEC-based tension-reduction-detection (PTRD) system are (1) a low-cost (< $ 30), low-power (< 2 Watts) sensor, (2) a short inspection time (< 10 seconds), (3) high reliability and (4) the potential for embedded sensing. A 3.3 m long full-scale monostrand PT tendon was used to evaluate the performance of the proposed PTRD system. The PT tendon was tensioned to 180 kN using a custom universal tensile machine, and the tension was decreased to 0 kN at 20 kN intervals. At each tension, the PEC responses were measured, and tension reduction was successfully detected.

Keywords

Acknowledgement

Supported by : Ministry of Land, Infrastructure and Transport (MOLIT)

References

  1. Abdullah, A.B.M., Rice, J.A. and Hamilton, H.R. (2015), "Wire breakage detection using relative strain variation in unbonded posttensioning anchors", J. Bridg. Eng., 20, 04014056. https://doi.org/10.1061/(ASCE)BE.1943-5592.0000639
  2. Bartoli, I., Salamone, S., Phillips, R., Lanza Di Scalea, F. and Sikorsky, C.S. (2011), "Use of interwire ultrasonic leakage to quantify loss of prestress in multiwire tendons", J. Eng. Mech., 137, 324-333. https://doi.org/10.1061/(ASCE)EM.1943-7889.0000227
  3. Brown Jr, W.F. (1965), "Theory of magnetoelastic effects in ferromagnetism", J. Appl. Phys., 36(3), 994-1000. https://doi.org/10.1063/1.1714293
  4. Goins, D. (2000), "Motor speedway bridge collapse caused by corrosion", Mater. Perform., 37, 18-19.
  5. Hanna, K.E., Morcous, G. and Tadros, M.K. (2009), "Transverse post-tensioning design and detailing of precast, prestressed concrete adjacentbox-girder bridges", PCI J., 54(4), 160-174.
  6. Hieber, D.G., Wacker, J.M., Eberhard, M.O. and Stanton, J.F. (2005), State-of-the-Art Report on Precast Concrete Systems for Rapid Construction of Bridges, Report No. WA-RD 594.1, Washington State Transportation Center (TRAC), University of Washington, U.S.A.
  7. Jiles, D.C. and Atherton, D. L. (1986), "Theory of ferromagnetic hysteresis", J. Magn. Magn. Mater., 61(1-2), 48-60. https://doi.org/10.1016/0304-8853(86)90066-1
  8. Lee, J., Kim, J.M. and Sohn, H. (2017), "Magnetostriction analysis of a post tensioning tendon system under varying tension forces", Proceedings of the Advances in Structural Engineering and Mechanics (ASEM17), Ilsan, Korea, August.
  9. Lee, D.H. and Kim, K.S. (2011), "Flexural strength of prestressed concrete members with unbonded tendons", Struct. Eng. Mech., 38(5), 675-696. https://doi.org/10.12989/sem.2011.38.5.675
  10. Ma, Z., Tadros, M.K. and Sun, C. (2004), "Prestressed concrete box girders made from precast concrete unsymmetrical sections", PCI J., 49(1), 80-90.
  11. Mohammed, A.H. and Taysi, N. (2017), "Modelling of bonded & unbonded post-tensioned concrete flat slabs under flexural & thermal loading", Struct. Eng. Mech., 62(5), 595-606. https://doi.org/10.12989/SEM.2017.62.5.595
  12. Kim, J.M., Lee, J. and Sohn, H. (2017), "Automatic measurement and warning of tension force reduction in a PT tendon using eddy current sensing", NDT & E Int., 87, 93-99. https://doi.org/10.1016/j.ndteint.2017.02.002
  13. Kim, J.M., Kim, H.W., Park, Y.H., Yang, I.H. and Kim, Y.S. (2012), "FBG sensors encapsulated into 7-wire steel strand for tension monitoring of a prestressing tendon", Adv. Struct. Eng., 15, 907-917. https://doi.org/10.1260/1369-4332.15.6.907
  14. Proverbioi, E., and Ricciardi, G. (2000), "Failure of a 40 years old post tensioned bridge near seaside", Proceedings of the International Conference of Eurocorr, London, U.K.
  15. Sofia, M.J. and Homsi, E.H. (1994), "Fabrication and erection of precast concrete segmental boxes for baldwin bridge", PCI J., 39(6).
  16. Tadros, M.K., Al-Omaishi, N., Seguirant, S.J. and Gallt, J.G. (2003), Prestress Losses in Pretensioned High-Strength Concrete Bridge Girders, Report No. HCHRP 496, Transportation Research Board.
  17. Woodward, R. and Willians, F. (1988), "Collapse of Ynys-y-Gwas bridge West Glamorgan", Proceedings of the Institution of Civil Engineers, 84, 635-669. https://doi.org/10.1680/iicep.1988.179
  18. Wang, G., Wang, M.L., Zhao, Y., Chen, Y. and Sun, B. (2005), "Application of EM stress sensors in large steel cables", Smart Struct. Mater., 5765, 395-406.
  19. Zhao, X. and Lord, D.G. (2006), "Application of the villari effect to electric power harvesting", J. Appl. Phys., 99, 2014-2017.

Cited by

  1. Numerical assessment of the damage-tolerance properties of polyester ropes and metallic strands vol.79, pp.1, 2018, https://doi.org/10.12989/sem.2021.79.1.083