Flexural performance of partially prestressed concrete beams incorporating steel fibers in the tension zone

Steel Fiber Reinforced Concrete (SFRC) is a composite material known for its excellent flexural strength and enhanced structural integrity, particularly in prestressed concrete (PSC) beams. This study investigates the combined effects of prestressing, silica fume, and steel fiber incorporation on the flexural behavior of reinforced concrete beams. The primary objective was to evaluate the effectiveness of steel fibers placed specifically in the tension zone of partially prestressed concrete beams. A total of seven post-tensioned reinforced concrete beams were tested under a four-point bending setup to assess their flexural response. Corrugated steel fibers were incorporated into the concrete mix at volume fractions of 0.5%, 1.0%, and 1.5%. Along with the control specimen, additional beams were cast with steel fibers distributed throughout the full depth of the section and confined to the tension zone. Experimental findings exhibit that the combination of steel fibers and prestressing tendons significantly improved key flexural parameters, including load-carrying capacity, crack resistance, ductility index, and energy absorption capacity. Furthermore, the results indicated that the partially fiber-reinforced beams (FRC-P) exhibited comparable flexural performance to the fully fiber-reinforced beams (FRC-F). This approach of selectively reinforcing the tension zone with fibers enhances the ductility and strength of RC beams while achieving structural performance comparable to that of full-depth fiber reinforcement, making it an efficient and economical use of fibers. Finally, regression analysis was carried out for all flexural parameters using MATLAB, and the analytical results were correlated with experimental observations.