Effect of anchor’s inclination angle on the flexural enhancement of CFRP-strengthened RC beams

Carbon fiber-reinforced polymers (CFRP) spike anchorage systems demonstrated positive outcomes in mitigating debonding of CFRP sheets in externally strengthened reinforced concrete (RC) beams. This study aims to investigate the effect of inclination angle of the CFRP spike anchors dowel on the flexural behavior of strengthened and end-anchored RC beams. Three concrete beams having a length, depth, and width of 2000, 250, 200 mm, respectively, were tested under a four-point bending test. The first beam was strengthened and unanchored, and the other two beams were strengthened and anchored with vertical (θ=90°) and inclined CFRP anchors at an angle of 135° on each side, respectively. The dowel’s diameter of the anchors used in this study is 14 and 20 mm, respectively. Results showed that the failure observed in the beam having inclined anchors was unfavorable. An abrupt separation in the concrete cover occurred that was even more brittle than the unanchored beam. Moreover, the percentage increase in flexural strength of the beam with inclined anchors was 23% with respect to the unanchored beam, compared to an increase of 40% demonstrated by the beam with vertical anchors. Therefore, it can be concluded that using inclined anchors is not recommended in strengthened RC beams for flexure.