Structural Unsymmetrical can be a major reason for the poor performance of buildings under severe seismic loading, Unsymmetrical contributes significantly for translational-torsional coupling in the seismic response which can lead to increased lateral deflections, increased member forces and ultimately collapse. In this paper the inelastic seismic behaviour of symmetric and asymmetric single & multi-storied buildings are studied. The effects of torsion on buildings are investigated. There is an increase in shear in columns and the rotation of columns need some special attention. Although seismic response of building asymmetric in the plan has been studied in the past in great detail, the contribution of the torsional resistance of the individual columns in total torsional response is not well understood. In order to study that, in the present work a multi storey structure (asymmetric plan) with three degrees of freedom is modelled in two ways, viz. Once with column replaced by springs and next with columns modelled is they are. In the latter case the torsional rotation of individual columns can be obtained while in the former case, it is not possible. Considerable difference between the two responses is observed.

Symmetric & Asymmetric buildings, spring model, base shear, time history, spectral acceleration, spectral displacement, spectral velocity.