A generalized conditional intensity measure approach and holistic ground motion selection
The rigorous selection of ground motions is an important consideration in a seismic risk assessment as it provides the link between seismic hazard (seismology) and seismic response (earthquake engineering). Despite the fact that many studies have highlighted the differences between the uniform hazard spectrum (UHS) and individual earthquake scenarios, the UHS is still the primary method by which ground motion records are selected and scaled. The conditional mean spectrum (CMS) is one alternative to the UHS for ground motion selection which provides the mean response spectral ordinates conditioned on the occurrence of a specific value of a single spectral period, and is directly linked to probabilistic seismic hazard analysis (PSHA). There are however several limitations in the use of the CMS for ground motion selection, which primarily stem from the fact that spectral accelerations provide only a partial picture of the true character of a ground motion. Based on the identified limitations of the CMS the objective of this work was to develop what is referred to as a generalised conditional intensity measure (GCIM) approach, which allows for the construction of the conditional distribution of any ground motion intensity measure. A holistic method of ground motion selection was also developed based on the comparison of the empirical distribution of a ground motion suite and the GCIM distributions.