Performance-Based Seismic Retrofitting of Existing Reinforced Concrete Buildings Using ETABS: A Review of Structural Deficiencies, Assessment Methods and Strengthening Techniques

A considerable proportion of existing reinforced concrete buildings were designed according to outdated standards or primarily for gravity loads, without adequate consideration of seismic forces and ductile detailing. Such structures commonly exhibit insufficient lateral stiffness, excessive storey displacement, weak beam–column joints, soft-storey behaviour and poor energy-dissipation capacity. This review examines seismic deficiencies in existing reinforced concrete buildings, available assessment procedures and commonly adopted retrofitting techniques. Particular attention is given to column jacketing, reinforced concrete shear walls, steel bracing, fibre-reinforced polymer strengthening, base isolation and energy-dissipation systems. Previous analytical and experimental investigations indicate that column jacketing improves confinement, strength and ductility, whereas shear walls provide substantial lateral stiffness and deformation control. Steel bracing offers an efficient alternative by reducing storey displacement and drift with comparatively low additional mass and limited interruption to building occupancy. The review also discusses the application of ETABS for three-dimensional modelling, equivalent static analysis, response spectrum analysis and comparative performance assessment of original and retrofitted structures. Storey displacement, inter-storey drift, base shear, natural time period and member forces are identified as critical response parameters. The reviewed literature establishes that retrofit selection should consider structural performance, architectural compatibility, foundation demand, construction feasibility, cost and expected performance level. Greater emphasis on nonlinear assessment, experimental validation and cost–benefit evaluation is recommended.