Role of fiber reinforcement on lap splices behavior

Bond behavior involves the formation of radial transversal pressure as a result of the wedge action of the crushed concrete between the bar ribs. The latter may cause the onset of longitudinally split- ting cracks when the tensile strength is reached in the concrete cover. The propagation of splitting cracks, and thus the brittle failure of the anchorage or a splice, can be efficiently counteracted by the confinement action provided by stirrups and/or by the post-cracking residual strength of fiber reinforced concrete (FRC), which allows a more uniform distribution of bond stress along a splice. Several full-scale beams reinforced with rebars of different diameters were tested with different percentages of longitudinal reinforcement lapped at mid-span. A traditional volume fraction of hooked steel fibers (equal to 0.5%) was adopted for FRC. Experimental results show that the toughness of FRC can enhance the behavior of the weak joint with only lapped bars. The capability of FRC to control the flexural and splitting crack opening and propagation can increase the strength of staggered lapped splices, thus allowing a reduction of lap length.