Authors: Harish Mishra, Dr. Hariram Sahu
Abstract: Reinforced concrete (RC) moment-resisting frames are widely used in multi-storey construction but are inherently flexible under lateral seismic loading, which can lead to excessive storey drift, non-structural damage and, in severe cases, structural collapse. Supplementing an RC frame with steel bracing is one of the most widely researched and applied means of improving its seismic performance, and a large and growing body of literature has examined the many forms this strategy can take. This paper presents a review of published research on steel-braced RC frames, covering the classification of bracing systems (concentric diagonal, X, V, inverted-V/chevron and K arrangements; eccentric and off-diagonal bracing; buckling-restrained and self-centering braces), their reported effects on lateral stiffness, storey displacement, inter-storey drift, ductility and energy dissipation, the influence of building height and structural irregularity on bracing effectiveness, retrofit and brace-to-frame connection strategies, and the analytical, numerical and experimental methods used to evaluate them. The review finds broad agreement that steel bracing substantially improves lateral stiffness and reduces storey drift relative to a bare RC frame, that X-type and inverted-V (chevron) configurations are the most frequently reported as most effective for stiffness and drift control though the relative ranking varies between studies, and that eccentric and buckling-restrained systems offer superior ductility and energy dissipation at some cost in stiffness. The review also identifies persistent gaps in the literature, including a shortage of controlled, zone-wise or intensity-wise comparisons of a single bracing configuration across the full range of seismic demand, limited experimental validation of brace-to-RC-frame connection detailing at full scale, and a continuing reliance on linear or pushover-level analysis rather than nonlinear time-history assessment for tall buildings. These gaps are identified as priorities for future research.
