[cat] Different shear-transfer actions on concrete beams have been well-studied in many research works to understand the mechanical behavior of RC beams failing in shear. In this research, a detailed investigation is conducted to evaluate six simple supported RC beams without stirrups by the detailed tracking of crack kinematics with photogrammetry techniques. Research focuses on a refined measurement of crack kinematics throughout the experimental test for different longitudinal reinforcement ratios. The result highlights marked redistribution of shear-transfer actions very close to failure, where aggregate interlock contribution changes from irrelevant to primary. The principal remarks aim to gain a better understanding of rational approaches for shear design through critical shear crack behavior to bridge the gap between shear strength design models with apparent contradictory initial hypotheses.