Abstract The main objective of this work is to study the performance of prestressing steel (PS) bars as reinforcements in the reinforced concrete (RC) elements strengthened by the near-surface mounted method (NSM). The work includes two parts. In the first part, direct pull-out tests are performed in order to study the bond performance between PS reinforcement and concrete. The influences of groove sizes and PS surface conditions (smooth and sand coated) are evaluated. The results show that the sand coated PS (PS-Sc) reinforcement has the best adhesion behavior compared with the smooth bar, and its pull-out force is increased by 48%. For this reason, the PS-Sc bars are used in the second part of this work as NSM reinforcement to strengthen RC beams subjected to bending forces. Then, four-point bending tests are carried out to understand the flexural behavior of strengthened RC beams with PS-Sc reinforcements of different lengths and ratios. The obtained results demonstrate that the use of NSM-PS-Sc bars strengthening technique leads to important enhancement in the load carrying capacity of the RC beams. The first crack load and ultimate load of the strengthened RC beams attain 71.41 and 65.67%, respectively, which are higher than those of the control beam. Furthermore, the experimental values show a good agreement with the analytical values in both the ultimate deflection and the ultimate load. This proves that the NSM-PS-Sc bars studied in this work are promising reinforcement of the RC beams.

中文翻译：

---

近表面安装预应力钢 (PS) 钢筋加固钢筋混凝土构件的粘结和抗弯加固

摘要 这项工作的主要目的是研究预应力钢 (PS) 钢筋在通过近表面安装法 (NSM) 加固的钢筋混凝土 (RC) 元件中作为钢筋的性能。作品包括两部分。在第一部分中，进行了直接拉拔试验，以研究 PS 钢筋与混凝土之间的粘结性能。评估凹槽尺寸和 PS 表面条件（光滑和砂涂层）的影响。结果表明，砂包覆PS（PS-Sc）钢筋与光滑钢筋相比具有最佳的附着性能，其拉拔力提高了48%。因此，本工作的第二部分使用 PS-Sc 钢筋作为 NSM 钢筋，以加强受到弯曲力的 RC 梁。然后，进行四点弯曲试验以了解具有不同长度和比率的 PS-Sc 钢筋的加强 RC 梁的弯曲行为。所得结果表明，使用 NSM-PS-Sc 钢筋加固技术可以显着提高 RC 梁的承载能力。加固钢筋混凝土梁的首裂荷载和极限荷载分别达到71.41%和65.67%，高于控制梁。此外，实验值与极限挠度和极限载荷的分析值非常吻合。这证明在这项工作中研究的 NSM-PS-Sc 钢筋很有希望增强 RC 梁。所得结果表明，使用 NSM-PS-Sc 钢筋加固技术可以显着提高 RC 梁的承载能力。加固钢筋混凝土梁的首裂荷载和极限荷载分别达到71.41%和65.67%，高于控制梁。此外，实验值与极限挠度和极限载荷的分析值非常吻合。这证明在这项工作中研究的 NSM-PS-Sc 钢筋很有希望增强 RC 梁。所得结果表明，使用 NSM-PS-Sc 钢筋加固技术可以显着提高 RC 梁的承载能力。加固钢筋混凝土梁的首裂荷载和极限荷载分别达到71.41%和65.67%，高于控制梁。此外，实验值与极限挠度和极限载荷的分析值非常吻合。这证明在这项工作中研究的 NSM-PS-Sc 钢筋很有希望增强 RC 梁。实验值与极限挠度和极限载荷的分析值非常吻合。这证明在这项工作中研究的 NSM-PS-Sc 钢筋很有希望增强 RC 梁。实验值与极限挠度和极限载荷的分析值非常吻合。这证明在这项工作中研究的 NSM-PS-Sc 钢筋很有希望增强 RC 梁。