Flexural Behavior of Steel Fiber Reinforced Concrete Beams

Abstract

The main objective of this study was to inspect the effect of steel fiber ratio into the flexural behavior of large-scale doubly reinforced concrete beams using an experimental method. For this purpose, four RC beams were constructed at the Structural Mechanics Laboratory of İzmir Katip Çelebi University and three-point bending tests were carried out. Two out of four were selected to be control specimens and did not have any fiber additive. To investigate the behavior free from shear reinforcement effect, one of the control specimens did not have stirrups while the remaining one had a minimum amount of stirrup according to TS500 [1]. Last two beams had either 0.5 or 1% volume fractions (Vf) of hooked end fibers, respectively. All the beams were designed to have 150x200x2450 mm prismatic geometry with a 1.30% tensile reinforcement ratio. The used materials were commercially available S420B grade steel for reinforcement and in-house cast concrete having a mean cylindrical compressive strength of 25 MPa. Based on the test results it can be stated that having a minimum amount of stirrup according to TS500 or 0.5% steel fiber enabled the beams to fully use their flexural capacity instead of an enhancement in the capacity. In other words, steel fibers contributed to the shear strength similar to that of beam with minimum amount of stirrup. However, increasing the volumetric ratio of steel fibers to 1.0% did not only contributed on the behavior but also slightly enhanced the flexural capacity (10%) of beam specimen, basically depending on the increase in the moment capacity of the cross-section.