Cracking behavior of reinforced concrete beams strengthened with CFRP anchorage system under cyclic and monotonic loading

•This study presents an experimental study of RC beams strengthened with CFRP fabrics and anchors subjected to monotonic and cyclic loading.•The crack patterns are studied by analyzing the fractal dimension and supersonic non-destructive detective detection.•The test results show that CFRP anchors could remarkably prevent the premature debonding of CFRP sheets.•A combination of fractal analysis and supersonic detection is applicable for the assessment of damage of RC specimens. This paper presents the details of an experimental and analytical study that addresses the influence of carbon fiber-reinforced polymer (CFRP) anchors on the bearing capacity and fatigue behavior of reinforced concrete beams strengthened by CFRP strips. The experimental set comprised seven beams from which four beams strengthened by CFRP strips and anchors of four different lengths were first subjected to cyclic loading, and subsequently loaded until failure under monotonic loading. The remaining three beams were designed to establish the baseline response. The residual bearing capacity, damage degree, cracking behavior and ultrasonic inspection were analyzed. The results showed that the length of CFRP anchors significantly influenced the residual bearing capacity and failure modes of the specimens. A deep anchoring depth may result in a brittle failure of the specimen at the mid-stage of cyclic loading. In addition, based on the good correlation between residual bearing capacity and the fractal dimension of surface cracks of the beams, a novel damage index was proposed. The results also demonstrated that fractal dimension analysis together with ultrasonic inspection could be exploited to assess damage levels when mechanical testing is not available.