Flexural performance evaluation of NSM basalt FRP-strengthened concrete beams using digital image correlation system

This study investigates the flexural behavior of reinforced concrete beams strengthened with near surface mounted (NSM) basalt fiber reinforced polymer (BFRP) bars. A total of five concrete beams with a length of 2100 mm were prepared with different internal longitudinal reinforcement and strengthening reinforcement ratios. Four-point bending tests were conducted under monotonic loading. A digital image correlation (DIC) technique was used to monitor full-field displacement and strain contours as well as mid-span deflections. The strains in the BFRP bars were recorded using strain gauges. The force-displacement curves, longitudinal strains in NSM reinforcement, and crack widths were computed and used to evaluate the performance of the strengthened beams. Results indicate that the NSM BFRP bars can successfully restore the original capacity of a concrete beam with a corroded internal reinforcement while providing a more ductile behavior. In addition, the ultimate load capacity of the reinforced concrete beams can be augmented using NSM BFRP bars but in an expense of smaller deflection capacity.