Mitigating Seismic Pounding in L-Shaped Adjacent Steel Buildings Using Bracing Systems

L-shaped buildings are particularly vulnerable to seismic actions due to their inherent geometric irregularity, which leads to uneven stiffness distribution and complex dynamic behaviour. When such buildings are located close together, the risk of seismic pounding increases significantly, potentially causing local damage, amplifying inter-storey drift, and leading to progressive structural deterioration. This study investigates the effectiveness of bracing systems in mitigating seismic pounding between adjacent L-shaped steel buildings. A nonlinear time-history analysis framework was developed to assess the structural response to three representative earthquake records (Ko-be, Chi-Chi, and Northridge). Three bracing configurations, namely X-, V-, and inverted V-bracing, were examined. The results indicate that bracing systems can significantly influence the distribution of seismic response rather than simply reducing it. While back-side bracing effectively suppresses pounding at the rear interface, it may shift the critical interaction to the front side. Among the configurations examined, X-bracing and inverted V-bracing provide more balanced performance in controlling both displacement and inter-storey drift, whereas V-bracing shows less consistent behaviour, despite reducing base shear in some cases. Overall, the findings demonstrate that seismic pounding mitigation in adjacent irregular buildings is governed by a complex interplay between stiffness modification and load redistribution. Therefore, the effectiveness of bracing systems cannot be assessed using a single performance indicator and requires a multi-criteria evaluation.