Flexural Strengthening of Continuous Reinforced Concrete Beams with Near-Surface-Mounted Reinforcement

Abstract

This experimental study attempts to investigate the flexural behavior of continuous reinforced concrete (RC) beams strengthened by near-surface-mounted steel bars. The tests were conducted on 11 3,000-mm specimens with cross-sectional dimensions of 150 × 225 mm. The longitudinal reinforcement of all beams consisted of two ϕ10 steel bars in the negative and positive moment regions. To ensure that the beams would fail under flexure rather than shear, ϕ10 stirrups were spaced at 100 mm c/c over the entire beam length. The first beam was not strengthened and was considered a control beam. The other specimens were strengthened by near-surface-mounted bars with different development lengths, diameters, and material types, with end-anchors of carbon-fiber-reinforced polymer (CFRP) fabrics. The test was conducted under two-point loads, applied at the center (1,400 mm) of the span. The main investigated characteristics were cracking and ultimate loads, crack width, displacement, and failure modes. From the experiments, all the strengthened beams achieved a significant enhancement in ultimate flexural strength by approximately 108% relative to the control beam. In addition, CFRP end-anchorage can eliminate the separation of the concrete cover and demonstrates a significant improvement in ductility.