Experimental quantification of the cracking localization phenomenon in tensile r/frc bars

This paper describes an experimental study that aimed to verify and quantify the cracking localization phenomenon in a structural member that includes both conventional reinforcement and fibers (R/FRC). Cracking localization, which is not typical to reinforced plain concrete, is characterized by non-uniform widening of relatively few cracks under increased deformations and it has been observed in R/FRC members with low amounts of conventional reinforcement. The experiments comprised R/FRC bar specimens of constant cross-section and fiber contents with several rebar diameters (i.e., with various conventional reinforcement ratios) that were tested under axial tension up to post-yielding of the rebar. Initial results show that as the rebar diameter increased, more cracks widened evenly. These results conform to the previously observed localization phenomenon and provides a quantitative relation between the reinforcement ratio and the number of cracks that exhibited localization. Quantification of this relation may lead the way to a rational setting of a minimum reinforcement ratio, which is required to prevent cracking localization in R/FRC structural members.