Cyclic behavior of corner beam-column connections retrofitted with HPFRCC under bidirectional loading

Many existing older reinforced concrete (RC) moment frames were originally designed only for gravity loads. These structures often exhibit poor performance under large seismic events. Among their components, corner beam-column connections are particularly vulnerable due to their unique configuration of restraint by only two adjoining beams, unlike interior or exterior connections. Additionally, these corner connections are more significantly affected by bidirectional ground motions and torsion due to plan irregularity. The objective of this study is to enhance the cyclic behavior of older corner beam-column connections using High-Performance Fiber Reinforced Cementitious Composites (HPFRCC). Experimental tests were conducted with four full scale connection specimens. The loading protocol reflecting a realistic loading condition was determined from nonlinear response history analyses. This study demonstrated that the use of HPFRCC significantly improved the cyclic behavior of corner beam-column connections.