Application of shear horizontal guided waves for nondestructive damage detection in thin-walled ultra-high performance concrete

While guided wave-based techniques have been extensively developed for various engineering materials, their application to ultra-high performance concrete (UHPC), particularly in thin-walled structures, remains underexplored. This paper presents a shear horizontal (SH) guided wave technique for the nondestructive assessment of thin-shaped UHPC, specifically mimicking pipeline components. The proposed technique leverages SH mode guided waves for two key purposes: (1) the quantitative evaluation of mechanical properties and (2) the precise estimation of defect geometry. An 8 mm-thick UHPC plate sample was used to investigate the detection of frontal defect shapes and acoustic properties by utilizing the dispersive traits of SH mode waves. The results confirm the nondispersive nature of SH wave propagation at frequencies between 120 and 150 kHz, ensuring accurate measurements of wave velocity and attenuation coefficients for UHPC. This study also compares the short-time Fourier transform (STFT) method employed for signal processing with the conventional Hilbert envelope (HE) method, identifying 140 kHz as the optimal frequency for effective defect localization and shape characterization in the UHPC sample. The findings from this preliminary study can contribute to establishing new maintenance guidelines for thin UHPC structures, with potential applications in hyperloop systems and complex architectural designs.