Influence of steel reinforced grout configuration, and reinforcement ratio on the flexural performance of strengthened continuous <scp>RC</scp> beams

Abstract The field of reinforced concrete (RC) strengthening continues to evolve as the construction industry seeks cost‐effective and sustainable alternatives to structural replacement. This study, therefore, aimed to comprehensively investigate the pioneering application of steel‐reinforced grout (SRG) for strengthening large‐scale, 3.5‐meter‐long continuous RC beams. The main purpose was to explore the complex interplay among SRG density, the number of SRG layers, and the steel reinforcement ratio, and to assess their collective impact on the structural performance of the strengthened beams. Extensive experimental testing was carried out on 10 large‐scale RC continuous beams, including two pristine beams serving as references. The experimental findings demonstrated significant enhancements in the load‐carrying capacity of the strengthened beams, achieving increases ranging from 24% to 104% compared to the corresponding reference beams. Although a reduction in ductility was observed, this emphasized the need to optimize the balance between strength and deformation in the strengthened members. The use of low‐density SRG proved remarkably effective, providing superior bonding and higher efficiency, while high‐density SRG exhibited slightly lower performance due to reduced matrix penetration. Additionally, the number of SRG layers was found to play a crucial role in boosting the load capacity, with more pronounced effects in beams with lower steel reinforcement ratios. To complement the experimental investigation, two theoretical models based on the SRG effective strain were developed and validated against the experimental results. The close agreement between the models and the experimental data underscores their potential as practical tools for the design and optimization of SRG‐strengthened beams, thereby contributing critical insights for engineering applications.