Analysing the critical orientation of seismic loading in 3D buildings: preliminary results for constant lateral forces

The angle of seismic excitation has been proven to be an important factor when analysing the 3D behaviour of buildings. However, modern earthquake-related standards only cover partially the effects of this factor and relevant studies are still limited. The proposed paper focuses on the determination of the critical angle of incidence based on the building's structural characteristics. An analytical expression is developed to define the critical angle for the case of single storey buildings and a special category of multi storey buildings under constant lateral forces assuming linear elastic behaviour of the structures.