In this study, the effects of fiber orientation within the carbon fiber reinforced (CFRP) sheets, on the fracture mode and crack growth of specimens were investigated by constructing five groups of initially notched self‐consolidating concrete beams, and strengthening them with CFRP sheets in the tensile area. Furthermore, the bearing capacity, strain variation along the sheet, crack mouth opening, and the midspan displacement were recorded by varying the height of the beams and the initial notch lengths. The results indicate that the load‐crack mouth opening curves have two peak load points. First, the applied load increases up to one peak value and then there is a drop in the load‐caring capacity. Afterwards, the applied load is improved to another peak value due to the relatively high cohesive effect of the CFRP sheet. The results show that as the height of the beam section increases, or the initial notch length decreases, the first and the second peak loads increase. By comparing the specimens with different fiber angles in each group, it was observed that the specimen with fiber angle 0° has a higher capacity relative to other angles, yet its failure occurs in a lower displacement. Furthermore, with the help of finite element software and nonlinear static analysis, the behavior of the aforementioned beams including the stress and strain distributions in the CFRP sheet, and the sheet‐to‐concrete bond zone have been examined and compared with the existing experimental results for validation.
The current study presents numerical and experimental approaches in the assessment of fracture behavior of self-consolidating concrete beams strengthened with carbon fiber-reinforced polymer (CFRP) lamina. The failure modes, mid-span displacement, and the load-bearing capacity of specimens with initial notches at mid-span are analyzed by varying the notch length and the beam height. Furthermore, the effects of variations in CFRP and concrete mechanical properties, bond strength, and notch location are examined by using the non-linear finite element analysis. Findings reveal that stress concentration in concrete and CFRP, in the vicinity of initial notch, as well as the failure of specimens occur as a result of CFRP debonding and crack extension. Moreover, it is observed that load-mid-span displacement curves are characterized by two peak load points strength. At the first stage, the applied load increases up to one peak value and then at the second stage there is a drop in the load-caring capacity. The applied load is then improved to another peak value due to the relatively high cohesive effect of the CFRP sheet at the third stage. Among different variables, the second peak load shows higher sensitivity to variations of the elastic modulus of CFRP, and bond strength at interface. As the notch approaches the beam support, and hence the relative distance from mid-span changes from 0 to 2/3, the two peak loads are respectively escalated by 116 and 58%, and thus the inclined crack propagates toward mid-span.
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