Seismic resilience of RC structures with shape memory alloys: Past and new perspectives

This review comprehensively investigates the role of shape memory alloys (SMAs) in enhancing the seismic resilience of reinforced concrete (RC) structures. Emphasizing the unique properties of SMAs, superelasticity (SE) and the shape memory effect (SME), the study classifies their applications across various RC elements, including beams, columns, shear walls, and beam-column joints. The review synthesizes findings from more than 100 experimental studies, detailing both internal and external SMA deployments, and highlights the performance metrics most relevant to seismic design: residual drift, energy dissipation, stiffness degradation, and load-carrying capacity. Distinct comparisons are drawn between Ni-Ti, Cu-based, and Fe-based SMAs, offering clarity on their context-specific advantages. A significant contribution of the study is the structured evaluation of hybrid systems that integrate SMAs with supplementary materials such as ECC, UHPC, and FRP, which demonstrate enhanced composite action and address SMA limitations such as low damping. The review identifies critical gaps in long-term performance data, implementation feasibility, and design standardization, and offers forward-looking recommendations for multi-material hybrid configurations, coupler development, and codification pathways. This work offers a consolidated reference point for researchers and practitioners seeking to advance the practical development of SMA-based solutions toward broader structural applications in seismic regions. By addressing key research gaps, the study advances the understanding of SMA applications in seismic engineering and outlines future directions for achieving resilient and sustainable RC structures.