Flexural behavior of reinforced concrete beams strengthened with near-surface mounted 7075 aluminum alloy bars

Newly developed aluminum alloy (AA) bars with high strength, good ductility, and excellent corrosion resistance are gradually utilized for retrofitting or strengthening reinforced concrete (RC) structures. This paper investigates the potential application of 7075 aluminum alloy bars as the near-surface mounted (NSM) reinforcement in flexural strengthening of RC members. A total of five reinforced concrete beam specimens including one reference beam and four specimens strengthened with NSM 7075 AA bars were designed and loaded monotonically up to failure. The NSM reinforcement ratio and anchorage of U-jacket were selected as the test variables to investigate the flexural behavior of strengthened beam specimens. It is observed from the test results that the flexural capacity of the strengthened beams increased by more than 35% in comparison with reference specimen owing to the application of the NSM AA system. Increasing NSM AA reinforcement ratio brought about a linear increase in the load bearing capacity of the strengthened beams. The anchorage of CFRP U-jacket can enhance the load-bearing capacity and displacement ductility for the strengthened beam specimens by preventing or delaying the premature failure which included interfacial debonding and concrete cover separation. Furthermore, analytical models were used to calculate the load versus mid-span deflection relationship and predict the debonding failure load of the strengthened beams. Good agreements were achieved between the predicted results and experimental results.