seismic retrofitting of corner rc beam-column joints with floor slab: numerical assessment of hybrid and composite systems

This paper presents a finite element investigation into the seismic performance and retrofitting of corner rc beam-column joints with an attached floor slab—a realistic detail often neglected in previous studies. seven models, including code-compliant, non-ductile, and five advanced retrofitting configurations (external steel cages, bolted steel boxes, externally bonded cfrp, and hybrid steel–frp systems), were analyzed under monotonic loading using a calibrated damage plasticity approach. explicit modeling of the slab–joint interaction enabled a realistic assessment of strength, ductility, and damage control. results indicate that hybrid retrofitting strategies, particularly cfrp-bsb and bsac, significantly enhance both ductility and damage mitigation, matching or surpassing the performance of code-compliant specimens. cfrp-only and cfrp-nsm systems also provided substantial gains in energy dissipation and control of inelastic damage, while the bsb method, despite increased strength, showed greater localization of plastic strains. analysis of the principal plastic strain index and force–displacement curves highlights the value of integrated composite and steel confinement in restoring seismic resilience to vulnerable joints. these findings provide practical recommendations for the seismic upgrade of existing rc beam-column  joint with floor slabs, emphasizing the importance of considering slab effects, advanced hybrid retrofitting, and robust damage indices in retrofit design and assessment.