Experimental and reinforcing index‐based modeling of tensile stress–strain behavior of graded glass fiber reinforced concrete

Abstract Advancements in the research of fiber‐reinforced concrete (FRC) have pressed the need to predict its tensile stress–strain behavior, which remains complex until now due to the limited experimental data available. This study presents both the experimental and theoretical analysis to predict the tensile stress–strain behavior of graded glass fiber reinforced concrete (GGFRC) using the graded fiber reinforcing index (RI GF ). The model incorporates fiber lengths of 3, 6, 12, and 20 mm at a 0.3% volume fraction for M50 grade concrete. Results indicate that shorter fibers (3 and 6 mm) improve tensile strength, while longer fibers (12 and 20 mm) enhance the deformation capacity. A combination of different fiber lengths produces a synergistic effect, with longer‐graded fibers (12 and 20 mm) offering better deformation and energy absorption compared to shorter fibers (3 and 6 mm). The grading of short (3 and 6 mm) and long (12 and 20 mm) glass fibers significantly altered the behavior compared to their corresponding mono‐fiber systems. Among all graded mixtures, SGF‐II (40% 3 mm + 60% 6 mm) and LGF‐II (40% 12 mm + 60% 20 mm) demonstrated the most significant improvements in mechanical strength and deformation capacity within their respective short‐ and long‐fiber categories. Finally, this study established a predictive RI GF model based on fiber characteristics that precisely represents the tensile stress–strain characteristics of GGFRC and forecasts its idealized performance, which closely corresponds with the experimental findings.