Flexural behavior of reinforced composite beams with crack‐controlling layer: Experimental analysis and analytical modeling

Abstract This study investigates the flexural behavior of reinforced composite beams with a crack‐controlling layer, such as engineered cementitious composite (ECC) or fiber‐reinforced concrete (FRC), using a combination of experimental analysis and theoretical modeling. To examine the flexural behavior of the beams, 28 composite beams and one reinforced concrete (RC) beam were fabricated, focusing on five key parameters: the thickness and type of the crack‐controlling layer, longitudinal reinforcement ratio, fiber type, and interface condition. Experimental results were analyzed to identify failure modes, mid‐span cross‐section strain distribution, load‐deflection behavior, crack load, ultimate load, crack propagation patterns, and crack width. The findings highlighted the effectiveness of polyvinyl alcohol‐ECC (PVA‐ECC) as an ideal material for the tensile zone of RC beams, significantly improving flexural performance and crack resistance. An analytical framework was developed to predict the flexural behavior of composite beams with an ECC layer, incorporating the strain‐hardening behavior of ECC within the conventional cross‐section analysis model for RC beams. This framework was validated against experimental data from concrete‐ECC composite beams. Additionally, the study proposed a model to determine the critical thickness of the ECC layer. The model's predictions showed strong agreement with experimental results, demonstrating its ability to accurately forecast failure modes and crack propagation patterns in composite beams with an ECC layer.