Seismic Performance of Reinforced-Concrete Beam-Column Joints With Conventional Steel and Hybrid Shape-Memory-Alloy/Fiber- Reinforced-Polymer Reinforcement: A Critical Review

Abstract Background Reinforced-concrete (RC) beam-column joints are critical regions in moment-resisting frames because they must transfer large cyclic moments, shear forces, and axial forces while maintaining anchorage integrity and structural continuity during earthquakes. Conventional steel-reinforced joints can provide substantial strength and hysteretic energy dissipation when properly detailed, but severe cyclic loading may produce reinforcement yielding, bond deterioration, joint shear damage, corrosion-related durability problems, and permanent residual deformation. Purpose —This review critically evaluates conventional reinforcement, shape-memory-alloy (SMA) reinforcement, fiber-reinforced-polymer (FRP) systems, and emerging SMA+FRP hybrid concepts for improving the seismic performance and resilience of RC beam-column joints. Coverage Particular emphasis is placed on literature published from 2023 to 16 August 2026, supplemented by landmark earlier studies required to establish joint mechanics, SMA constitutive behaviour, FRP strengthening principles, and the origin of hybrid SMA-FRP concepts. Findings —The literature indicates that SMA reinforcement is particularly effective for self-centering and residual-deformation control, whereas FRP systems are attractive for corrosion resistance, joint shear strengthening, confinement, and minimally invasive rehabilitation. However, SMA systems can provide narrower hysteresis than yielding steel, while FRP performance is strongly controlled by bond, anchorage, fiber orientation, substrate condition, and brittle failure. Hybridization offers a rational means of combining restoring capability with strength, confinement, durability, and energy-dissipation mechanisms. Research gap —Direct, recent, full-scale experimental validation of true SMA+FRP RC beam-column joints remains sparse, particularly under bidirectional loading, variable axial force, slab participation, temperature effects, aftershocks, and multi-hazard exposure. Conclusion —SMA+FRP hybrid joints represent a promising resilience-oriented structural concept, but standardized detailing, validated nonlinear models, probabilistic performance assessment, life-cycle evaluation, and code-ready design procedures are required before routine engineering implementation.