Flexural Behavior of Over-Reinforced Concrete Beams Strengthened with Steel Fiber

Adding steel fibers for the reinforced concrete (SFRC) increase some properties of concrete such as the tensile strength, shear strength, toughness and the flexural strength. Most specifications limit the reinforcement ratios in the beams to avoid the brittle failure. However, sometimes a high reinforcement ratio is used in order to minimize beam depth and still provide adequate stiffness. The objective of this work is to investigate and evaluate the using of steel fiber in improving the behavior of over-reinforced beams and its effect on the enhancement of strength and ductility of such beams was presented. The present study aims to investigate the effect of steel fiber on the behavior of the over reinforced concrete beam in terms of crack formation, displacement, and deformation. Six over-reinforced concrete (RC) beams were tested in this study to use steel fibre at various depths to improve the flexure behaviour and ultimate strength capabilities. One is a control beam without steel fibers, three beams of steel fibre ratios 0.5%, 1%, and 2% by volume of concrete were applied to reinforce them to half depth. The final two beams were strengthened completely with the two steel fibre ratios of 1% and 2%. The beams were tested in flexure under one-point loading system. The ultimate load, First cracking load, mid span deflections and steel reinforcement strains were investigated and compared, using the outcomes for the control beam as a benchmark, the flexural behaviour of the SFRC beams was examined and contrasted. SFRC beams were discovered to display ductile behaviour, good fracture management, efficient flexure strengthening, and noticeably decreased mid-span deflection based on the examination of the data. However, they are inversely proportional to the steel strain, crack width, fracture spacing, ductility, and mid-span deflection. The steel to fibre ratio and distributed volume are directly related to the initial stiffness, cracking load, and failure load.