A COMPARISON OF PULL-OUT AND TENSILE BEHAVIORS OF FRP REINFORCEMENT FOR CONCRETE

Commercially available FRP reinforcement rods with well-controlled variations in depth and pitch of indented helical wrappings were investigated experimentally and analytically to determine the effect of rod geometry on (1) concrete bond strength and (2) stand-alone tensile strength and modulus. Maximum bond stress increased with increasing indent depth, but did not display any particular dependence on indent pitch. Loaded-end slip at the onset of free-end slip increased with increasing embedment length and decreasing rod diameter and was relatively constant for rods with similar embedment length to diameter ratios. In tension tests, deeper indents weakened the rods while smaller indent pitches strengthened the rods. Parameters for a general analytical model of local slip within the embedment length were determined.