Experimental Investigation of Flexural Cracks in Light Reinforced Concrete Beam

This study investigates the flexural crack behavior of lightly reinforced concrete (RC) beams through experimental analysis. Six beams with varying reinforcement ratios and dimensions were subjected to three-point bending tests to understand the crack initiation, propagation, and branching phenomena. Materials were characterized through standard tests, and the beams were cast with M30 grade concrete, reinforced using high-yield strength deformed bars. A notch was introduced at mid-span to ensure controlled crack initiation. The experimental observations showed that reinforcement influenced crack branching and ductility behavior significantly. Beams with higher reinforcement ratios exhibited delayed crack propagation, greater energy absorption, and enhanced ductility, while unreinforced beams failed through a single dominant crack. Crack width development and crack mouth opening displacement (CMOD) were monitored using high-resolution imaging and microscopic tools. The study concludes that crack branching contributes to increased ductility by redistributing stresses during failure and that beam depth and reinforcement ratio critically affect the crack propagation mechanism. The results emphasize the importance of crack control and ductility enhancement in the design of lightly reinforced concrete structures, providing a foundation for improved fracture modeling and structural resilience.