Seismic Retrofitting of Existing RC Buildings: A Comprehensive Review of Methods, Analysis Techniques, and Future Directions

India is one of the most seismically active countries of the world with about 50-60% of its land area being seismically prone. The majority of RC buildings built prior to the seismic code of practice are highly vulnerable to seismic events due to lacking lateral load resistance. Over the last ten years, seismic retrofitting has become an effective and feasible approach to improve building performance without demolition. This review paper summarizes the most recent approaches, computational analysis frameworks, non-destructive evaluation (NDE) techniques, and performance-based engineering design aspects employed in seismic rehabilitation of existing reinforced concrete (RC) structures. It combines the results of the best international studies conducted between 1999 and 2024 with a focus on comparing retrofit technologies from the past with the new ones. The literature always shows that a retrofit implementing a combination of shear wall additions, steel bracing, fibre-reinforced polymer (FRP) jacketing and optimisation of infill walls performs better than any single retrofit technique in terms of reducing storey drifts, bending moments, shear, and axial load. It is possible to reliably characterize in-situ concrete strength by non-destructive testing (NDT) including the rebound hammer method for pre-retrofit. Advanced software platforms such as STAAD. Accurate linear and non-linear seismic simulations are achieved using Pro, SAP2000 and ETABS. This provides opportunities to incorporate damage prediction using machine-learning, real-time structural health monitoring (SHM) sensors, and to continue the analyses with shape-memory alloy (SMA) dampers in tall structures subjected to combined wind and dynamic loading scenarios.