Experimental and analytical study of RC beams strengthened with prestressed near-surface mounted 7075 aluminum alloy bars

Recently developed high-strength aluminum alloys (AA) have great potentials for strengthening and repairing RC structures because of their merits in high strength-to-weight ratio, high ductility, and inherently corrosionresistant behaviors. However, few studies have been conducted on taking advantage of AA bars for rehabilitation. This study was therefore carried out to reveal the feasibility of 7075 AA bars on near-surface mounted (NSM) applications for flexural strengthening of reinforced concrete (RC) beams. Experiments of four-point flexural tests were presented to assess the performance of NSM AA bar strengthened beams through eight concrete beams, including a control specimen without strengthening, a specimen strengthened by conventional basalt fiber reinforced polymer (BFRP) bars served as reference, and other six ones using NSM AA strengthening technique with various prestress level and bar arrangement. Results indicate that the application of the strengthening system was able to prevent premature debonding failure and increase the load-bearing capacity by up to 102.1%, but reduced the deformability. In addition, an analytical model for capturing the load-deflection behavior of various strengthening schemes was developed. Good agreements between the results from observations and predictions validated the proposed model, suggesting its potential for guiding the design of the AA strengthening schemes.