Effect of Steel Fiber Content on Behavior of Concrete Beams with and without Stirrups

An experimental study is conducted on a series of 12 reinforced concrete and steel fiber-reinforced concrete beam specimens, to study their shear and flexural strengths, failure mechanisms, and ductility response under monotonic loadings. The main parameters varied in this study are the concrete compressive strength, percentage of longitudinal reinforcement, fiber content, shear span-depth ratio, and amount of transverse stirrups. End-hooked steel fibers of volume fraction ranging from 0.5 to 1.5% are used in the specimens. Test results showed that, the addition of steel fibers enhanced the flexural and shear strengths and the ductility of the flexural members. The addition of a minimum of 0.5% fiber content in the beams with shear stirrups changed the mode of failure from brittle to ductile, whereas a minimum fiber content of 1.0% is required, to achieve the ductile response of the beams without shear stirrups. Using a curve-fitting method on the available test data, simple expressions are also derived to predict the shear strengths of medium- to large-scale flexural members with varying fiber contents.