239. HEALTH MONITORING OF PRESTRESSING TENDONS BY ULTRASONIC GUIDED WAVES AND EMBEDDED SENSORS

Department: Structural Engineering
Faculty Advisor(s): Francesco Lanza di Scalea

Primary Student
Name: Robert Ronald Phillips
Email: rrphilli@ucsd.edu
Phone: 858-534-5279
Grad Year: 2011

Student Collaborators
Ivan Bartoli, ibartoli@ucsd.edu

Abstract
As the main load-carrying components, prestressing tendons (PS) are critical structural elements in post-tensioned concrete structures. In order to provide real-time information on the level of prestress and the presence of structural defects in the PS tendon much research is needed. UCSD in collaboration with Caltrans is investigating the development of such techniques to be deployed in pre-existing and future structures that will provide the required information to evaluate the current health state of these PS tendons. Structural monitoring methods based on Guided Ultrasonic Waves (GUWs) have the potential for both defect detection and stress monitoring as an active approach. GUWs have been used for the detection of defects in multi-wire strands and reinforcing rods (Kwun and Teller, 1995; Beard et al. 2003; Reis et al. 2005) and for the evaluation of stress levels in post-tensioning rods and multi-wire strands (Kwun et al. 1998). As a passive approach, acoustic emission techniques have been shown to have potential in the detection of corrosion and the onset of strand cracking in PS tendons. This is a summarization of the representative results to date by the authors on the application of the active and passive monitoring for defects and prestress levels in PS tendons.

Kwun, H. & Teller, C.M. 1995. Nondestructive Evaluation of Steel Cables and Ropes Using Magnetostrictively Induced Ultrasonic Waves and Magnetostrictively Detected Acoustic Emissions. U.S. Patent No. 5,456,113, 1995. Kwun, H., Bartels, K.A. & Hanley, J.J. 1998. Effect of tensile loading on the properties of elastic-wave in a strand. Journal of the Acoustical Society of America, 103: 3370-3375. Beard, M.D.; Lowe, M.J.S. & Cawley, P. 2003. Ultrasonic guided waves for inspection of grouted tendons and bolts. ASCE Journal of Materials in Civil Engineering, 15: 212-218. Reis, H., Ervin, B.L., Kuchma, D.A. & Bernhard, J.T. 2005. Estimation of corrosion damage in steel reinforced mortar using guided waves. ASME Journal of Pressure Vessel Technology, 127: 255-261.

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