Corrosion monitoring of post-tensioned concrete structures using fractal analysis of guided ultrasonic waves

This work presents a new approach based on fractal analysis of guided ultrasonic waves (GUWs) for monitoring the corrosion evolutionary path in post-tensioned systems. Fractal analysis is a new scientific paradigm that has been used successfully in many fields including biological and physical sciences. However, its application in the SHM community has been modest. The proposed approach utilizes piezoelectric transducers, permanently attached to the steel tendon, to transmit and receive GUWs. The corrosion monitoring is performed through the examination of the fractal dimension of GUW measurements over time. Accelerated corrosion tests were carried out on two 7 wire steel strands embedded in two concrete blocks to validate the proposed system. Finally, an outlier detection algorithm is proposed to enhance the sensitivity of the technique to the corrosion-induced damage. Copyright (c) 2013 John Wiley & Sons, Ltd.