Investigation of the behavior of steel fiber reinforced concrete beams

High strength concrete is increasingly used in the construction of reinforced concrete structures. It is known that high strength concrete is a more brittle material when compared to normal strength concrete. Therefore, steel fibers can be added to the concrete mixture to improve the ductility of high strength concrete. It is very important to determine the behaviour of steel fiber reinforced concrete members for accurate analysis and design of members. In the presented thesis study, the behaviour of steel fiber reinforced concrete beams has been investigated. In the study, a total of eight beam specimens were prepared. The reinforced concrete beam specimens were 150×200×1750 mm (b×h×L) in sizes. One beam specimen was prepared without steel fiber and the other seven specimens were manufactured with different hooked end steel fibers (3D, 4D, 5D) and with different amount of steel fiber dosages (20, 40, 60 kg/m3). The beam specimens were tested under four-point bending loading to determine the structural behaviour. In the tests, the crack propagations were observed, the load and corresponding strains and deflections were recorded. The experimental load-deflection curves of the beams have been obtained using the experimental load and deflection values. In addition, a numerical procedure has been presented to obtain the theoretical load and load-deflection curves of reinforced concrete beams in the study. In the analysis, the nonlinear behaviour of the concrete material has been considered. The tested beam specimens were analysed and compared with test results. A good degree of correlation has been obtained between experimental and theoretical results. Optimum amount of steel fiber dosage has been recommended for beams by taking into account the obtained results of the study. It is concluded in the presented study that steel fibers significantly effect on the load carrying capacity of reinforced concrete beams.