Characterization of steel-concrete interface bonding conditions using attenuation characteristics of guided waves

This paper presents an air-coupled ultrasonic nondestructive evaluation approach based on the attenuation characteristics of guided waves to characterize interface bonding conditions of steel-clad concrete structures. Analytical guided wave modal solutions for various interface bonding conditions are obtained using the global matrix technique. The analytical results indicate that attenuation behavior of the fundamental symmetric (S0) guided wave mode is sensitive to interface bonding condition. A signal processing scheme is proposed to extract a dimensionless damage index, the normalized S0 mode magnitude, which reflects the attenuation behavior of the S0 mode. A series of numerical simulations are performed to verify the utility of the parameter to characterize interface bond condition. The feasibility of the testing approach is then established by experiments on steel-clad concrete specimens with different interface bonding conditions. The numerical simulation and experimental results demonstrate that interface bonding conditions of steel-clad concrete structures can be quantitatively evaluated using the proposed approach.