Seismic Analysis of Multistorey Structure by N2 Method

Earthquakes induce significant lateral forces that influence the stability and performance of reinforced concrete buildings, particularly those with structural irregularities.This study evaluates the seismic performance of four reinforced concrete building models using the N2 method: a regular G+4 building, an L-shaped G+4 building, an L-shaped G+4 building with setback irregularity, and an irregular G+10 building.Modal analysis was carried out to determine the dynamic characteristics of each model.Key seismic parameters, including fundamental period, modal mass participation, eccentricity, storey displacement, storey drift, storey shear, and hinge formation, were analysed.The N2 method was used to identify the performance point and evaluate the nonlinear seismic response of the structures.The results indicate that geometric irregularities increase torsional effects and displacement demands, while greater building height leads to higher storey displacements and shear.Despite these variations, all models satisfied the codal drift limits and achieved acceptable seismic performance, demonstrating the effectiveness of the N2 method for performance-based seismic assessment.