UHPC Reinforcement of Damaged RC Beams under Load Conditions Cracking and Bending Performance

In order to study the mechanical properties of damaged reinforced concrete (RC) beams reinforced with ultra-high-performance concrete (UHPC), a four-point bending test was conducted to systematically investigate the influence of factors such as the number of reinforcement surfaces and the degree of damage. The results indicate that single-sided repaired beams have certain advantages in crack resistance performance, but are more disadvantageous in ultimate bearing capacity, with obvious debonding phenomenon before the end of loading. Compared with single-sided reinforcement, the cracking load of the three-sided reinforced beam increased by an average of 1.85 times, the ultimate bearing capacity increased by an average of 177.5%, and a good UHPC-RC combination effect could be formed, which could work synergistically until the end of loading. The degree of pre damage has a significant impact on the crack resistance performance of reinforced beams, while its impact on the ultimate bearing capacity is relatively limited. When the pre splitting width of the RC beam increases from 0.2 mm to 0.4 mm, the ultimate bearing capacity decreases by 28.33%. Finally, a calculation formula for the ultimate flexural bearing capacity of damaged RC beams reinforced with UHPC was proposed, taking into account the degree of pre damage to the RC beams and the three-sided repair. The calculated results showed a high degree of agreement with the experimental data.