Shear failure in reinforced concrete beams is characterized by a sudden and brittle response posing significant risks to structural safety particularly in high-performance cementitious matrices. Although silica fume improves strength and durability it often reduces crack limit. This study addresses gap by establishing a direct equivalence between material-level interpretation and beam-scale shear behavior using concrete mixes containing 5% silica fume and steel fibers at volume fractions (Vf) of 0%, 0.75%, 1.0% and 1.25% were prepared among them 1.0% identified as optimum mix based on that an experimental program comprising cubes, cylinders and beam testing complemented by SEM-EDX microstructural analysis was conducted to investigate fiber-matrix interaction. Beam specimens were casted and tested under 4-point loading with a (a/d) ratio of 1.9 adapted limited transverse reinforcement to induce shear-critical behavior. Results indicate that RCSF0% fibers showed diagonal tension cracking leading to brittle shear failure within shear span. whereas, the RSCF1.0% mix demonstrated enhanced load capacity improved deformation resulting in a distinct shift from shear-dominated to flexure-controlled behavior. The findings further reveal that even with relatively larger stirrup spacing, steel fibers effectively bridged cracks at the microstructural level, enhancing shear resistance and improving the ductility and stability of the shear-critical structural members.
