Nondestructive In Situ Imaging of Preexisting Cracks in a Concrete Bridge Using Ultrasonic Coda Wave.

This paper presents an in-situ study of imaging cracks in the Berwick Bay Bridge nondestructively by the application of an inverse algorithm to ultrasonic coda wave measurements. Using only five sensors to collect coda signals, we have monitored a 100×70×33 cm3 volume of the bridge subjected to a sequence of static load tests, without prior knowledge of cracks. Whereas spatiotemporal waveform decorrelations can indicate global damage conditions, our inversion algorithm produced a three-dimensional map of change density that revealed the location and lengths of multiple 0.1-mm-scale cracks in reinforced concrete. [ABSTRACT FROM AUTHOR]