Acoustic Emission monitoring of shear strengthened reinforced concrete beams with HPFRC

Shear failures in ageing reinforced concrete (RC) structural elements present a critical challenge in structural engineering, as they are inherently brittle and often catastrophic. Effective retrofitting strategies are urgently needed, particularly for structures designed to outdated codification or subjected to increased service loads and climate-induced actions. High-Performance Fibre Reinforced Concrete (HPFRC) jackets have shown significant potential to enhance the shear strength of RC members and control cracking. There has been limited work on the mechanisms governing damage initiation and evolution in shear strengthened RC beams. This study presents an experimental investigation on the performance of HPFRC-strengthened shear deficient RC beams using different strengthening configurations and synthetic fibre contents (1.1%-1.75%). The RC beams have been tested under four-point bending and monitored using Acoustic Emission (AE) testing and Digital Image Correlation (DIC) to investigate damage initiation and evolution. The HPFRC jackets enhanced the shear capacity relative to the unstrengthened control beam, yielding improvements of 12.9-48.8% for the single and double-sided jacket configurations. AE feature-based analysis has detected damage initiation and evolution before the cracks were visible in the DIC. The presented findings demonstrate the potential of AE for assessing strengthened RC members. Keywords: Acoustic emission, Shear strengthening, Damage detection, High-performance fibre reinforced