Retrofitting of the reinforced concrete beams using external tightened steel bars

Several techniques were considered to retrofit the reinforced concrete members suffering damages or design mistakes. The present study investigates experimentally using a tightened bar system as an externally applied reinforcement installed straightly to provide additional strength to the partially or completely damaged concrete beams. The study involves testing 13 reinforced concrete beams classified into two groups based on the location of the externally applied reinforcement, either one bar installed beneath the lower face of the beam or two bars added to both sides of the beam. The study also investigates changing the loading ratio during the first stage of loading (40, 80, and 100) % of the ultimate load capacity of the control specimen. The third adopted parameter was the location of anchorage system devices for the beam edges, which was 10 cm or 25 cm. The results exhibited that the externally straight threaded tighten steel bar enhanced the ability of partially or completely damaged concrete beams to withstand additional loading in the range of (4–69) % above the original ultimate load capacity of the beam. Furthermore, the anchorage system on the bottom side of the beam was more efficient than the anchorage system on both sides. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.