Compression damage analysis of GFRP-steel fiber reinforced concrete composite structures based on AE and DIC techniques

This study employed an integrated approach using acoustic emission (AE) and digital image correlation (DIC) techniques to investigate the mechanical properties and compression damage characteristics of GFRP-steel fibre reinforced concrete (GSFRC) short columns. Results showed that increasing steel fibre content enhances peak load and displacement ductility by 31.55% and 15.60%, respectively. AE energy evolution categorises the failure process into three stages, with Kaiser effects observed during crack development. RA (rise time/amplitude)-AF (average frequency) distribution characteristics correlate with concrete failure modes, where shear cracks increase with higher fibre content, while reduced b-values in the elastic-stage signal impending fracture in SFRC. The probability density distribution of AE energy exhibits distinct avalanche characteristics, with avalanche indices quantifying the influence of steel fibre content on SFRC failure mechanisms. DIC technology captures the surface deformation evolution of GFRP tubes, enabling precise localisation of micro-damage through surface-line-point analysis. In addition, a Markov model based on AE parameters effectively predicted damage stages. The integrated AE-DIC approach provided multi-scale insights into GSFRC damage behaviour, combining macro-mechanical responses with micro-crack dynamics. This work offers a basis for optimising GFRP-steel fibre reinforced concrete composite structures and supports engineering safety evaluations.