A comparative study of frame structures with peripheral bracings and core shear walls subjected to blast load

Abstract The growing number of artificial and accidental explosions calls for the incorporation of special lateral load-resisting systems in contemporary tall building structures. This research presents a comparative study of the structural behaviour of reinforced concrete (RC) structures using different lateral force-resisting systems steel bracing systems in the form of X-braces, diagonal braces, inverted V-braces, and K-braces at periphery and core shear wall systems. Finite element modelling techniques using ETABS software have been used to analyse several G + 19 storey building models using blast loads based on IS 4991:2024. The method involves the computation of the peak reflected over pressures due to different TNT charges (125 kg and 250 kg) at standoff distances of 15 m to 20 m. An analysis of the results clearly revealed that compared with the base model (no braces), the peripheral X-brace model contributed 24.4% and 22.9% less to the structural resistance, respectively, for the critical blast condition (250 kg of TNT at a 15 m standoff distance). The second most efficient configuration was the inverted V-brace model, with a 19.7% decrease in storey displacement. An increase in explosive mass from 125 kg to 250 kg contributed to an anticipated rise in demand on the structure. However, a significant reduction in demand was achieved because of the increase in standoff distance from 15 m to 20 m, which resulted in a 25% decrease in storey displacement for all the models and the X-bracing structure exhibited excellent consistency, increasing the base shear demand by 32.5% to 34.8%, successfully shifting the dynamic energy loads and reducing the stress on the core wall. Thus, the combined core-wall/peripheral-bracing system, involving the core shear wall and X-braces, represents the feasible solution for protection against damage induced by short-duration blasts, whereas the V-bracing system stands out as the optimum solution when building requires façade openings.