Probabilistic Assessment of Torsional Buildings

Abstract

Abstract Asymmetry/irregularity is an undesired building characteristic that nevertheless exists commonly due to modern-day structural definitions. Asymmetry in plan, due to the uneven distribution of mass or stiffness can cause torsional coupling under seismic loads. A well-defined parameter that can sufficiently represent the damage of torsional buildings is non-existent, which may be why probabilistic seismic assessment methods such as fragility analyses have not been done for such buildings. The present study proposes ‘Resultant Drift’ as a parameter that can define the failure behaviour of asymmetric buildings and utilises the 2000 SAC FEMA method to analyse the seismic risk and develop fragility curves. The study observes the dependency of the extent of asymmetry and storey height on the failure probability. Investigations on the maximum storey rotation for the selected parameters show the necessity of international standard definitions in the performance levels of rotation behaviour.