Time History Analysis of Irregular Shape Building

Irregular-shaped buildings have become increasingly common in modern construction due to architectural innovation, yet they pose significant challenges in seismic design because of their complex dynamic behavior. This study investigates the seismic performance of various irregular building configurations L-shaped, C-shaped, T-shaped, rectangular, and square—using Time History Analysis (THA). Structural models of G+20 reinforced concrete buildings are developed in ETABS following IS 456:2000 and IS 1893 (Part 1):2016 standards. The 1940 El-Centro earthquake record is used as seismic input and scaled to multiple intensities to assess building response under varying levels of ground motion. Key parameters such as storey displacement, inter-storey drift, torsional irregularity, base shear, and floor accelerations are analyzed to understand the influence of geometric and stiffness irregularities. Results indicate that irregular buildings experience higher torsional effects and amplified lateral displacement compared to regular structures, making them more vulnerable during strong seismic events. The study highlights the limitations of conventional linear analysis methods, such as Response Spectrum Analysis (RSA), in capturing nonlinear dynamic interactions. Findings provide important insights for structural engineers and contribute to developing improved design strategies for enhancing the seismic resilience of irregular-shaped buildings.