COMPREHENSIVE STUDY ON STATIC AND DYNAMIC PROPERTIES OF HYBRID STEEL FIBER-REINFORCED CONCRETE (H_ySFRC) WITH STATISTICAL ANALYSIS USING RESPONSE SURFACE METHODOLOGY

This study explores the mechanical properties of hybrid steel fiber-reinforced concrete (H y SFRC) specimens, which highlights the impact of varying volumes of hybrid steel fibers on concrete performance. The specimens were prepared by a combination of 30[Formula: see text]mm short steel fibers (SSF) and 60[Formula: see text]mm long steel fibers (LSF), each with 1[Formula: see text]mm diameter. The investigation incorporates the compressive strength test, flexural strength test, splitting tensile strength test, and an impact resistance test with subsequent data analysis through response surface methodology (RSM). Key findings reveal that a mix with 0 vol.% LSF and 2 vol.% SSF ([Formula: see text]) at 2% [Formula: see text] achieves the highest compressive strength ([Formula: see text] of 44.11[Formula: see text]N/mm 2 at 28 days, which shows superior crack resistance and structural integrity. Additionally, a mix containing 0.5 vol.% LSF and 1.5 vol.% SSF at 2% [Formula: see text] demonstrates the optimal synergy between short and long fibers, resulting in improved flexural strength ([Formula: see text]) of 5.91[Formula: see text]N/mm 2 , splitting tensile strength ([Formula: see text] of 8.11 N/mm 2 after 28 days. Impact resistance is improved with a 3D network structure formed by steel fibers at 0.5% volume of LSF and 1.5% volume of SSF at 2% [Formula: see text]. High [Formula: see text] values (0.8850–0.9818) confirm precise response variable prediction, which validates the study’s reliability. The influence of hybrid steel fibers on [Formula: see text] is shown by the greatest F-value (140.53). Lambda values, Cook’s distance, and contour plots further confirm the stability of the RSM model and ideal mix conditions. These results offer a strong foundation for maximizing H y SFRC, improving its durability and structural performance.