2026 Volume 5 Issue 1 Pages 191-198
A number of bridges constructed over tidal rivers are managed by Ota Ward, necessitating more reliable and proactive maintenance. For this purpose, a new testing method is devised—the measurement of Rayleigh wave velocity using the impact-elastic wave method—aimed at detecting rebar corrosion at an earlier stage.
This method was applied to an actual bridge structure where salt damage is a concern, comparing the results with the corrosion status of internal rebars confirmed by core boring. Furthermore, the numerical analysis using a two-dimensional elastic wave equation was used to verify the mechanism behind the fluctuation of the measured values.
The results confirmed that when a void exists within the concrete, vibrations different from those in a sound area get mixed into the receiver. This causes a change in the phase spectrum, ultimately leading to the calculated Rayleigh wave velocity deviating from the sound area's measured value.
