Funding:

• • National Science Foundation

  • California Department of Transportation

Collaborators:

• • Prof. Jose Restrepo, UCSD

Purpose:

To develop strategies for both real-time health monitoring and periodic NDE inspections of post-tensioned concrete bridges. 

Synopsis:

This work builds on numerical and experimental data from post-tensioned concrete specimens, both small-scale and large-scale. We propose to deploy an array of ultrasonic transducers for simultaneous (1) passive sensing of Acoustic Emissions, and (2) active sensing of ultrasonic waves around the prestressing tendons.

The instrumentation recommended for the real-time health monitoring of existing or new PT bridges would include: (a) an array of small piezoelectric ultrasonic transducers installed on critical PS strands which monitor prestress levels by linear and nonlinear ultrasonic features; (b) an array of Acoustic Emission sensors installed at the anchorage plates of critical PS strands and in the concrete soffit which detect and locate, in real-time, structural damage (concrete cracking, wire breaks, tendon corrosion, tendon-grout disbonds) caused by either a loss of prestress or other factors (e.g. overloads). We are further investigating the use a statistical discrimination metrics which use multiple ultrasonic features collected from the sensor array to detect a Loss of Capacity of the bridge in real-time.

In addition to the real-time health monitoring, regularly scheduled NDE periodic inspections of the bridge need to be performed. We are testing for bridges the same idea used in proof testing of pressure vessels based on the known Kaiser Effect of Acoustic Emissions. Using this approach, which involves subjecting the bridge to periodic known loads and recording the corresponding AE events, it should be possible to detect any new damage on the bridge between the testing intervals. This idea was has proven promising in the large-scale tests of the PT joints conducted in collaboration with Prof. Restrepo’s group at UCSD Powell Structural Laboratory.

Selected Publications:

Salamone, S., Veletzsos, M., Lanza di Scalea, F., and Restrepo, J., “Detection of Initial Yield and Onset of Failure in Bonded Post-tensioned Concrete Beams,” ASCE Journal of Bridge Engineering, Special Issue on NDE/NDT for Bridge Inspection and Evaluation, 17(6), pp. 966-974, 2012.

Salamone, S., Bartoli, I., Phillips, R., Nucera, C., and Lanza di Scalea, F., “Health Monitoring of Prestressing Tendons in Post-Tensioned Concrete Bridges,” Journal of the Transportation Research Board, Transportation Research Record no. 2220, pp. 21-27, 2011.

Bartoli, I., Salamone, S., Phillips, R., Lanza di Scalea, F. and Sikorsky, C., “Use of Interwire Ultrasonic Leakage to Quantify Loss of Prestress in Multiwire Tendons,” ASCE Journal of Engineering Mechanics, 137(5), pp. 324-333, 2011.

Nucera, C. and Lanza di Scalea, F., “Monitoring Load Levels in Multi-wire Strands by Nonlinear Ultrasonic Waves,” Structural Health Monitoring International Journal, 10(6), pp. 617-629, 2011.

Bartoli, I., Salamone, S., Phillips, R., Nucera, C., and Lanza di Scalea, F., “Health Monitoring to Detect Failure of Prestressing (PS) Cables in Segmental Box-girder Bridges,” Technical Report No. CA-090938 to the California Department of Transportation, University of California, San Diego, 2009 (131 pages).

Lanza di Scalea, F., Bartoli, I., Rizzo, P., Marzani, A., Sorrivi, E., and Viola, E., “Structural Health Monitoring of Multi-wire Strands,” Chapter 151 of Encyclopedia of Structural Health Monitoring, C. Boller, F-K. Chang and Y. Fujino, eds., Johns Wiley & Sons, Chichester, UK, pp. 2487-2503, 2009.

Bartoli, I., Salamone, S., Phillips, R., Lanza di Scalea, F., Coccia, S., and Sikorsky, C., “Monitoring Prestress Level in Seven-wire Prestressing Tendons by Inter-wire Ultrasonic Wave Propagation,” Journal of Advances in Science and Technology – Embodying Intelligence in Structures and Integrated Systems, Vol. 56, pp. 200-205, 2008.

Rizzo, P., Sorrivi, E., Lanza di Scalea, F., and Viola, E., “Wavelet-based Outlier Analysis for Guided Wave Structural Monitoring: Application to Multi-wire Strands,” Journal of Sound and Vibration, Vol. 307(1-2), pp. 52-68, 2007.

Rizzo, P. and Lanza di Scalea, F., “Feature Extraction for Defect Detection in Strands by Guided Ultrasonic Waves,” Journal of Structural Health Monitoring, Vol. 5(3), pp. 297-308, 2006.

Rizzo, P. and Lanza di Scalea, F., “Wavelet-based Feature Extraction for Automated Defect Classification in Strands by Ultrasonic Structural Monitoring,” Smart Structures and Systems, Vol. 2(3), pp. 253-274, 2006.

Rizzo, P. and Lanza di Scalea, F., “Wave Propagation in Multi-wire Strands by Wavelet-based Laser Ultrasound,” Experimental Mechanics, Vol. 44(4), pp. 407-415, 2004.

Lanza di Scalea, F., Rizzo, P. and Seible, F., “Stress Measurement and Defect Detection in Steel Strands by Guided Stress Waves,” ASCE Journal of Materials in Civil Engineering, Special Issue on NDE/Health Monitoring, Vol. 15(3), pp. 219-227, 2003.