Experimental and analytical investigation of RC beams strengthened by ultra-high performance shotcrete

Currently, there is an increasing need for the repair of damaged structures, particularly those situated in confined and challenging locations. Historically, addressing such structures has been hampered by a lack of effective repair and rehabilitation methods. This study aims to investigate, both experimentally and analytically, the application of Ultra-High-Performance Shotcrete (UHPS) for strengthening and repairing reinforced concrete (RC) beams at the bottom. Five RC beams were cast, with one serving as a reference. The remaining four reinforced concrete beams were fabricated with grooved surfaces at the bottom. Subsequently, they underwent strengthening with UHPS at the soffit in two scenarios: one with reinforcements and one without reinforcements. The results indicate a significant enhancement in the load-carrying capacity of the composite beam, up to 126 %, when UHPS is combined with reinforcements. Additionally, the analytical method demonstrates good accuracy, with a maximum error of 16.62 % compared to the experimental results. These findings suggest that the utilization of UHPS effectively improves the structural behavior of RC beams, particularly in challenging locations. Furthermore, the proposed analytical method holds promise for practical application in the design field, offering a systematic approach for implementing UHPS and reinforcements in the repair and rehabilitation of reinforced concrete beams. •Mix design for UHPS is proposed.•UHPS-strengthened beams have higher ultimate load, energy absorption, and stiffness•Strengthening RC beams by UHPS combined with rebars are effectively.•An analytical method accurately predicts the loading capacity of UHPS-RC beams.