Assessment of Torsional Irregularity Ratio in Reinforced Concrete Buildings Incorporating Basement Shear Walls

This paper investigates the seismic performance of reinforced concrete (RC) buildings with shear walls placed at the basement, with emphasis on torsional irregularity ratio.The analytical models are developed and analyzed using FEMbased software such as SAP2000 v21 and ETABS 20, following the response spectrum method prescribed in the NBC code.The study evaluates torsional irregularity by examining modal mass participation ratios and torsional response parameters.Nonlinear static (pushover) analysis is also conducted with hinge assignments for beams, columns, and shear walls to capture the nonlinear behavior of the structure under increasing lateral loads.A parametric study is performed by varying the number of stories while keeping other parameters constant, allowing assessment of torsional irregularity trends with increasing building height.The findings highlight the influence of basement shear walls on controlling torsional irregularity and enhancing seismic performance of RC buildings.