Underwater inspection of concrete-filled steel pipes using guided waves

Concrete-filled steel pipes have been widely used as piles for supporting marine and civil structures. They provide good bending resistance and can be easily spliced for long depth installations. In addition, they have high strength and ductility and are an economical solution for bridges. However, these piles are usually exposed in water, particularly seawater, and thus the outside corrosion of the steel pipe can reduce the wall thickness and the corrosion-induced delamination of internal concrete can increase internal volume or pressure. To avoid this type of deterioration, appropriate inspection and repair techniques are required. The acoustic method is an attractive method for the interface delamination detection since it is relatively simple and versatile. Guided wave techniques have particularly strong potential for this type of inspection and the feasibility of the guided wave techniques for detecting the interface inspection is investigated in this paper. A special coupling mechanism for transmitting the guided waves is introduced for the experimental study. An analytical study is also carried out to identify the cylindrical guided wave modes that are sensitive to the interface separation. This study shows the feasibility of using guided waves for underwater inspection of concrete-filled steel pipes.