Experimental and numerical study on flexural enhancement of reinforced self-compacting concrete beams through various strengthening approaches

This investigation examines the efficiency of five distinct strengthening schemes employed to improve the flexural capacity of reinforced concrete (RC) beams. The adoption of strengthening schemes were near-surface mounted (NSM) using Glass fiber reinforced polymer (NSM-GFRP) and Basalt fiber reinforced polymer (NSM-BFRP) specimens, carbon fiber polymer (NSM-CFRP plate), welded wire mesh (NSM-WWM) and ultra-high performance fiber reinforced concrete (UHPFRC (layer. Seven RC beams with 1800 mm length, 150 mm wide, and 250 mm deep RC beam composed of self-compacting concrete (SCC) were tested under four-point bending. One RC beam with adequate flexural reinforcement functioned as the control, while the remaining six had insufficient reinforcement. One beam without strengthening represented the flexure-deficient control, while the other five were strengthened using NSM-GFRP rebars, NSM-BFRP, NSM-CFRP plate, NSM-WWM, and UHPFRC layer. The peak load, failure mode, load-deflection curve, cracking patterns, strain distribution, and ductility of each beam were thoroughly examined and compared. The findings of this investigation revealed that all adopted strengthening techniques led to an enhancement in the flexural capacity of the RC beams, ranging from approximately 18% to 118% in comparison to bare specimens. Beams reinforced with NSM CFRP plates exhibited a notable improvement in short-term deflection and crack width compared to the control beam, while beams strengthened with NSM FRP rebars demonstrated significant enhancements in load carrying capacity and ductility behavior. The enhancement in the flexural capacity of RC beams using small thickness of 20 mm UHPFRC layer and WWM layer was acceptable to the other strengthening schemes. The application of a UHPFRC layer also enhanced the beams’ capacity to control crack width. The UHPFRC layer stands out as a promising approach that can be employed for the restoration and recovery of flexure deficient RC beams. Analytical modeling was utilized to calculate the flexural capacity of the tested RC beams, producing outcomes closely consistent with experimental results.