Dynamic Analysis of Vertical Irregular Reinforced Concrete Buildings: Evaluating Blast Resistance and Soft Storey Vulnerabilities

The increasing occurrence of explosions from terrorism, industrial accidents, and military conflicts has highlighted the vulnerability of high-rise buildings to blast-induced forces. Traditional reinforced concrete (RCC) structures are primarily designed for static loads and often lack adequate resilience against dynamic, short-duration blast loads. This study focuses on the dynamic analysis of vertical irregular RCC buildings, specifically G+15, G+20, and G+25 structures, incorporating soft-storey configurations that are known to be highly susceptible to damage under impulsive loads. Blast loads are calculated following IS 4991:1968 and TM5-1300 standards, considering parameters such as peak overpressure, impulse duration, and standoff distance. The structural behavior under these loads is modeled and analyzed using ETABS through time-history simulations and finite element analysis (FEA). The study evaluates critical response parameters including displacement, inter-storey drift, shear forces, and base shear, comparing regular and irregular building configurations under varying blast scenarios. Results indicate that soft-storey irregularities significantly amplify deformations and drifts, particularly at lower floors and under closer blast proximity. The findings highlight the importance of strategic reinforcement, optimal shear wall placement, and material enhancements to improve blast resistance. This research provides valuable insights for designing safer and more resilient high-rise structures, contributing to enhanced structural performance in high-risk zones and informing guidelines for blast-resistant design in vertical irregular buildings.