Flexural experimental assessment of ductility of SFRC beams using longitudinal reinforcing bars

Nowadays, products are available to improve the performance of reinforced concrete elements, such as short fibers, which are available in different geometries and aspect ratios. However, the regulations and standards for building construction do not allow its use in elements of the seismic resistance system. Therefore, a composite material called SFRC (steel fiber reinforced concrete) is being widely used in slabs, shells, or coatings as reinforcement to replace welded wire meshes or as a control system for shrinkage and pressure cracks in tunnels. For this research, SFRC specimens were manufactured using two different steel fiber aspect ratios. Compression and tensile tests were made to evaluate the capacity of the composite matrix to dissipate energy outside the elastic range, and the complete stress-strain curve was obtained for all tested specimens.

Also, 3-m-long beams were fabricated using the concrete mixture with longitudinal (flexural) reinforcement and tested as four-point bending beams. In this case, using the deflection in the middle spam were calculated the entire bending moment vs. slope curves. As a result, the SFRC characteristic curves for normal stress (tensile and compression) as well as for bending moment were obtained. The ductility was calculated and compared with theoretical models proposed in the literature to describe the behavior of SFRC concrete in bending. Results show that the use of steel fibers in concrete mixtures increases energy dissipation and a controlled ductile failure for beams with flexural reinforcing bars without shear stirrups, being viable the possibility of including this type of reinforcement with fibers in elements with a demand for energy dissipation due to earthquakes.