Displacement controlled behaviour of structures subject to moderate ground shaking

Seismic assessment and design procedures are typically founded on the concept of trading off strength with ductility (displacement) to provide sufficient capability for the structure to absorb and dissipate seismically induced energy in an earthquake. However, in the regions of low to moderate seismicity, the kinetic energy demand of an earthquake will generally subside when the structure has been displaced to a certain limit. Consequently, the seismic performance of a structure can be controlled by its displacement capacity as opposed to its energy dissipation capability. This paper presents a seismic performance assessment method which accounts for the displacement-controlled phenomenon associated with moderate ground shaking. Parametric studies based on non-linear time-history analyses have been undertaken to identify the behavioural trends. Hysteretic models used in the studies were based on the observations of results from recent cyclic testings carried out at the University of Melbourne and the University of Adelaide. The effects of asymmetry in building systems on its seismic response behaviour have been investigated forming one of the main thrusts of the research. Results from parametric studies have been integrated to develop a simple and yet reliable alternative procedure for the seismic assessment of structures in regions of low and moderate seismicity like Australia.