층상화 단면해석을 통한 CFRP 보강 열화 RC 보의 휨 성능 평가

초록

This study analytically evaluates the flexural behavior of reinforced concrete (RC) beams strengthened with carbon-fiber-reinforced polymer (CFRP) after deterioration caused by combined freeze–thaw cycles and rebar corrosion. A layered section analysis model considering material nonlinearity was proposed and validated against experimental results. The model was designed to predict flexural behavior by simultaneously accounting for degradation of material properties due to deterioration and the strengthening effects of CFRP. The analysis results showed that the predicted yield and ultimate flexural moments for both deteriorated and CFRP-strengthened RC beams correlated well with experimental values, with an average ratio of predicted-to-experimental values ranging from 1.01 to 1.16. This confirms the model’s high reliability in predicting flexural capacity. However, discrepancies were observed in the moment–displacement relationship. In the pre-yield region, the model overestimated flexural stiffness compared with experimental results, which is attributed to its inability to fully capture nonlinear behaviors such as initial microcracking in concrete. Conversely, in the post-yield region of CFRP-strengthened beams, the model predicted lower stiffness than observed experimentally. This deviation is likely due to displacement calculations based on conventional RC theory, which do not adequately account for the high elastic modulus of CFRP reinforcement, resulting in an overestimation of displacement at ultimate capacity.

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