Multi-scale damage diagnosis and failure process reconstruction of steel fibre reinforced concrete: An integrated AE-MS study

Accurately characterizing the multi-scale failure mechanisms and damage accumulation of steel fibre reinforced concrete (SFRC) is essential for safety assessment and failure prevention. This study investigates the fracture process and mechanical response of SFRC with varying steel fibre contents (0–2%) and curing ages (3–28 d) under uniaxial compression. An integrated monitoring approach combining acoustic emission (AE) and micro-seismic (MS) techniques was employed to capture fracture precursors across different frequency bands, bridging the gap between micro-cracking and macroscopic failure. The multi-band signal analysis successfully revealed four distinct damage stages: compaction, elastic deformation, yielding, and post-peak softening. Crucially, a transition from shear-dominant to tensile-dominant failure was quantified via RA-AF analysis. By leveraging two-tiered correlation analyses, a robust quantitative link was established between the AE-MS damage indicators and the mechanical properties. Based on these findings, a novel AE-MS data-driven damage constitutive model was proposed to reconstruct the mechanical state and failure process. Calibrated with nine experimental groups and validated against three independent datasets, the model achieved a prediction accuracy with R² exceeding 0.95. These results demonstrate the potential of using multiband non-destructive signals to monitor the real-time damage state and predict the impending failure SFRC, providing a theoretical basis for intelligent engineering monitoring.