Flexural Behavior of Reinforced Concrete Beams with Various Layers of Conventional and Steel Fiber Reinforced Concrete

Flexural behavior of reinforced concrete (RC) beams having various layers of conventional concrete (CC) and steel fiber reinforced concrete (SFRC) were investigated in this study. Two groups of five beams (180x250x3500 mm) were tested under four-point loading to evaluate the flexural behavior. Both of these groups of beams were reinforced with 4 phi 16 reinforcing bars. The main variable in this research was the concrete type of the layers throughout the height of the specimen. The height of the cross-section of the beams was divided into 5 layers, each having 50 mm thicknesses. In group "F" specimens, SFRC layers were added to the layers of a CC beam, starting from the bottom, as replacements of CC layers, i.e. F15P10 represented that the bottom 150 mm was cast using SFRC whereas the top 100 mm was cast using CC. In group "P" specimens, CC layers were added to the layers of a SFRC beam, starting from the bottom, as replacements of SFRC layers, i.e. P10F15 represented that the bottom 100 mm was cast using CC whereas the top 150 mm was cast using SFRC. Experimental load-deflection curves were evaluated based on ultimate load, service/post-peak stiffnesses, and flexural toughness. It can be concluded that reasonable ductility may be achieved by adding SFRC at the tension side no matter how thick the layer is and where it is located.