Akademik Veri Yönetim Sistemi
JOURNAL OF REINFORCED PLASTICS AND COMPOSITES, 2026 (SCI-Expanded, Scopus)
This study investigates the high-temperature tensile performance of glass fiber-reinforced polymer (GFRP) bars embedded in concrete. To address limitations in the existing literature, where residual properties are often measured after cooling, the specimens in this study were directly tested at target temperatures of 100, 200, 300, 500, and 700 degrees C without any cooling phase, providing a more realistic assessment of the behavior of GFRP reinforcements under in situ fire conditions. The experimental program systematically investigated the stress-strain response, tensile strength, elastic modulus, ultimate strain, and toughness of GFRP bars to identify key degradation mechanisms under thermal loading. The results indicate that elevated temperature significantly affects the tensile performance of concrete-covered GFRP bars. Compared to room temperature (20 degrees C), the tensile strength decreased by approximately 43% at 300 degrees C and up to 95% at 700 degrees C, while the modulus of elasticity showed a reduction of about 34% at 300 degrees C and 69% at 700 degrees C. A critical transition was observed beyond 300 degrees C, where rapid degradation in mechanical performance occurred. The ultimate strain exhibited a slight increase from 2.35% to 2.52% at 200 degrees C, followed by a significant decrease to 0.39% at 700 degrees C, indicating progressive deterioration of the fiber-matrix interaction. Similarly, toughness decreased drastically from 110.94 J/mm3 at 20 degrees C to 0.85 J/mm3 at 700 degrees C, reflecting severe loss of energy absorption capacity. These findings demonstrate that maintaining the reinforcement temperature below approximately 300-400 degrees C is essential to preserve the load-carrying capacity of GFRP-reinforced systems under fire exposure conditions.