A COMPREHENSIVE REVIEW OF STEEL FIBER REINFORCEMENT EFFECTS ON POST-CRACKING BEHAVIORS AND ENERGY ABSORPTION CAPACITY OF HIGH-STRENGTH CONCRETE BEAMS UNDER FLEXURAL AND IMPACT LOADING CONDITIONS

Abstract

Steel fiber reinforced concrete (SFRC) has emerged as an advanced composite material that significantly enhances the structural performance of high-strength concrete (HSC), particularly under flexural and impact loading conditions. This comprehensive review synthesizes current research on the effects of steel fiber reinforcement on post-cracking behavior and energy absorption capacity of HSC beams. Conventional high-strength concrete, while offering superior compressive strength and durability, suffers from inherent brittleness and limited post-peak load-carrying capacity. The incorporation of discrete steel fibers addresses these limitations by enabling crack bridging, delaying crack propagation, and maintaining residual strength after cracking.

The review highlights that steel fiber volume fraction, geometry, and distribution critically influence mechanical performance. Optimal fiber contents ranging between 0.5% and 1.5% provide substantial improvements in flexural toughness, ductility, and residual load capacity without significantly compromising workability. Experimental findings demonstrate that SFRC beams exhibit enhanced load-deflection behavior, with toughness indices increasing up to tenfold compared to plain concrete. Under impact loading, SFRC shows remarkable improvements in energy absorption, with increases of 200–400% relative to conventional concrete, primarily due to fiber pullout mechanisms, frictional resistance, and distributed microcracking.

The study further evaluates strain-rate effects, revealing that steel fibers enhance dynamic response and sustain load capacity under high loading rates. Analytical and numerical models, including cohesive crack models and finite element approaches, have shown reasonable accuracy in predicting SFRC behavior, though challenges remain in standardization and parameter calibration. Additionally, emerging research on hybrid fiber systems and recycled steel fibers indicates promising directions for improving both performance and sustainability.