Bond behaviour between additional aluminium alloy ribs anchored CFRP bar and ultra-high ductile concrete

This study investigated the impact of incorporating additional aluminium ribs (ARs) on the bond behaviour of carbon fiber reinforced polymer (CFRP) bars in ultra-high ductile concrete (UHDC). The research conducted pull-out tests on 48 specimens with various parametric variables, including the number and location of ARs, the type of concrete material, and the depth of CFRP ribs. The outcomes revealed that the use of ARs significantly enhanced the bond performance of the CFRP bars in UHDC. The ultimate and residual bond strengths of both CFRP bars and AR anchored CFRP bars in UHDC surpassed those in ordinary concrete. The ARs also improved the rigidity of the bond-slip curve. Additionally, the bond performance of shallow-rib CFRP bars was substantially improved and comparable to that of deep-rib bars. The wave propagation method and wavelet packet analysis were employed to monitor the bond-slip process and to quantitatively analyze the degree of interface damage. The results suggested that increasing the extrusion length and number of ARs can improve the bond performance of the interface. Therefore, incorporating ARs can be considered as an effective approach to enhance the anchorage performance of FRP-reinforced concrete structures.