Analysis of the effect of aged concrete layer on RC beams, and a strengthening method employing carbon-fiber-reinforced polymer (CFRP) sheets

The numerical study focuses on the analysis of the structural behavior of concrete beams containing outdated concrete and offers an innovative method of strengthening them using carbon-fiber-reinforced polymer sheets (CFRP). The focus is on modeling and analyzing the performance of aged concrete beams strengthened by CFRP in the flexural direction. This study presents an ultimate load model for CFRP-strengthened RC beams featuring outdated concrete layers. Validation through four-point bending tests and finite element modeling demonstrated the efficacy of the model. Findings indicate that CFRP sheets significantly enhance beam strength, particularly in structures with outdated concrete layers, resulting in increased ultimate load capacity. Moreover, an inverse relationship between ultimate load and concrete layer height was observed, with the CFS-21-15-30 sample exhibiting the most substantial reduction. Validation of the model was achieved using finite element analysis con-ducted in Abaqus software.