Displacement controlled behaviour of asymmetrical buildings

Seismic assessment has traditionally been based on trading off strength with displacement (ductility) to provide sufficient energy dissipation capacity to structures. However, the energy demand on a structure from small to medium magnitude earthquakes will generally subside when the structure has been displaced to a certain limit. The significance of the concept of displacement-controlled behaviour in the seismic evaluation of a structure is that the peak drift demand of the structure can be constrained by a peak displacement demand which is solely a function of the properties of the ground shaking. In this paper, this concept has been extended for the seismic evaluation of asymmetrical structures. It is shown that a torsional amplification factor of 1.6 and 2.0 can be applied for estimating the peak drift demands of one-way and two-way asymmetric system respectively. By applying the new approach, the drift demand at the edges of the building can be estimated without applying the conventional force-based analysis.