Shear behavior of large and shallow fiber reinforced concrete beams

Steel fibers are very important in beams under shear loading, as evidenced from several scientific papers reported into the last decade journals. This paper reports some recent results of an experi-mental campaign on FRC beams under shear loading tested at the University of Brescia, focusing on the size effect issue and the shear behavior of shallow beams. With the first regard, nine full scale beams, having a height varying from 500 to 1500 mm, were tested to analyze steel fibers influence on size effect. Concerning the shallow beams, eight beams (all having depth of 250 mm) with two different widths, fiber content were tested for evaluating the shear response of typical structural members utilized in Southern Europe in residential buildings. Results show that a relatively low volume fraction of fibers can significantly increase shear bearing capacity and ductility. The size effect issue is substantially limited and it is observed that, with a fairly tough FRC composite, it is possible to completely eliminate this detrimental effect. Shallow beams do not show the typical brittle failure also without any shear reinforcement and the effect of fibers is even more prominent than in deep beams.