Corrosion damage estimation in multi-wire steel strands using guided ultrasonic waves

Abstract

This study presents a nondestructive evaluation method based on guided ultrasonic waves (GUW) to estimate corrosion in steel strands. Steel strands are one of the main components in constructing prestressed structures. Hidden corrosion in these structures has become a concern for designers, owners and regulators as it can eventuate in disastrous failure. In this study, a reference-free algorithm is proposed to quantify the extent of corrosion through estimating the cross section loss using dispersion curves and the velocity of certain frequency components in the waveform. Experimental test setups were designed to accelerate corrosion on two similarly loaded steel strands. One strand was embedded in concrete (to simulate a prestressed concrete beam) and the other was free (to resemble a prestressed cable). Visual inspection, halfcell potential, and mass loss measurements were employed as supporting evidences for the state of corrosion. An uncertainty analysis was also carried out to investigate how close this method can estimate the diameter of wires in a strand. The method could reasonably estimate the diameter of the wires without a reference baseline.