Sources of uncertainty and future research requirements in seismic analysis of structures

This Paper reviews the sources of uncertainty encountered in the analysis of structures subjected to earthquake loading and the research priorities required to reduce the identified uncertainty. Within a framework of loading and resistance, the sources of uncertainty are identified in the earthquake strong-motion input as well as in aspects of structural response. On the loading side, two examples are given to highlight the importance of earthquake duration and the effect of high vertical component of ground motion. A more comprehensive treatment of the resistance side is undertaken, as loading issues are covered by other Papers in this volume. Example analyses are given to emphasize the effect of decisions taken in modelling on the material, member, sub-assemblage and structure levels. This includes material stress-strain relationships, strain-rate effect, random variability, local buckling, confinement, large displacement, plasticity detection and overall buckling.