Seismic Analysis of Torsional Irregularity in Multi-Storey Symmetric and Asymmetric Buildings

Abstract

In buildings with multiple stories, one of the significant problems that continue to be documented involves torsion-induced failures. Particularly, structural torsion responses cause stress concentration and also alter the otherwise uniform translational seismic floor. In so doing, structural members require higher ductility and strength. Indeed, weaknesses in structures arise from factors such as stiffness and discontinuous geometry, a common source of failure especially when earthquakes are experienced. In this study, the central purpose is to examine building structural systems in relation to the impact of torsional behavior, especially in asymmetric and symmetric buildings constituting irregular plans. In situations where symmetric structures are present, the rigidity and mass center tends to coincide with one another. The eventuality is that for these structures, the torsion impact is attributed to accidental eccentricity. On the other hand, when asymmetric structures are present, stiffness and mass are distributed irregularly, with the resultant torsion causing structural seismic damage significantly. In this investigation, the objective is to evaluate the performance of each form of structure relative to various codes’ procedures regarding building practice. Some of the variables to be investigated include modal mass and frequency participating ratio, natural time-period, maximum lateral displacement, base shear, and storey drift. The motivation is to ensure that a comprehensive review is achieved regarding the targeted torsional irregularities’ structural response.