Flexural Behavior of RC Beams Externally Strengthened Using High-Performance Fiber Grid–Reinforced Concrete

Abstract The deterioration of reinforced concrete (RC) structures due to various factors significantly reduces their design life and can lead to catastrophic failure. Upgrading and strengthening are essential for deteriorated RC structures. Various strengthening techniques, such as RC jacketing, steel jacketing, and the fiber-reinforced polymers (FRP) technique, have been used to enhance flexural and shear strength. However, these methods have certain drawbacks, including durability issues with RC and steel jacketing, as well as delamination and debonding of FRP from the concrete substrate, particularly at elevated temperatures, which limits their application in many structures. This study primarily focuses on utilizing high-performance and high-strength grids, such as textile reinforcement with steel fiber-reinforced concrete (SFRC), to extend the service life of damaged and deteriorated RC beams. The experimental work investigates the effectiveness of flexural strengthening in deficient RC beams using two different type of textiles (glass fiber textile and geogrid) and the SFRC-based hybrid textile reinforcement concrete system (HTRC), offering an improved strengthening solution for RC beams. This study also addresses delamination and debonding issues associated with the externally bonded strengthening systems. The RC beams are strengthened using the proposed HTRC system and tested under static four-point loading. The test results include load-deflection behavior, cracking and failure mode analysis using digital image correlation, HTRC strain analysis, and various performance parameters such as the stiffness and strength degradation, energy absorbed, ductility, and damage index. The findings of this study demonstrate that HTRC as externally bonded strengthening system effectively restores design life capacity and enhances the overall structural performance.