THE INFLUENCE OF STEEL AND GLASS FIBER ADDITION ON SHEAR STRENGTH OF BEAM–COLUMN CONNECTIONS IN REINFORCED CONCRETE: AN EXPERIMENTAL INVESTIGATION

Abstract

Beam–column connections represent the most critical regions in reinforced concrete (RC) moment-resisting frames, particularly under seismic loading conditions. These joints are susceptible to brittle shear failure due to high stress concentrations and reinforcement congestion, which often compromises concrete consolidation. This experimental investigation evaluates the efficacy of discrete steel and glass fibers as supplementary reinforcement to enhance the shear strength and ductility of exterior beam–column connections. Nine full-scale specimens were cast and tested under monotonic loading, comprising one control specimen, four steel fiber-reinforced concrete (SFRC) specimens, and four glass fiber-reinforced concrete (GFRC) specimens. Fiber volume fractions ranged from 0.5% to 2.0%. The results indicate that the inclusion of fibers significantly alters the failure mode from brittle shear to a more ductile flexural mechanism. Steel fibers demonstrated superior performance in ultimate load capacity and energy dissipation, while glass fibers provided effective crack control and stiffness retention at lower costs. The study concludes that fiber reinforcement can partially replace traditional transverse steel in joint cores, offering a viable solution for seismic retrofitting and simplified construction in congested regions.