Truncation of the distribution of ground-motion residuals
By F. Strasser, J. Bommer, N. Abrahamson. 2008
72 citations recorded by the source corpus.
Recent studies to assess very long-term seismic hazard in the USA and in Europe have highlighted the importance of the upper tail of the ground-motion distribution at the very low annual frequencies of exceedance required by these projects. In particular, the use of an unbounded lognormal distribution to represent the aleatory variability of ground motions leads to very high and potentially unphysical estimates of the expected level of shaking. Current practice in seismic hazard analysis consists of truncating the ground-motion distribution at a fixed number (εmax) of standard deviations (σ). However, there is a general lack of consensus regarding the truncation level to adopt. This paper investigates whether a physical basis for choosing εmax can be found, by examining records with large positive residuals from the dataset used to derive one of the ground-motion models of the Next Generation Attenuation (NGA) project. In particular, interpretations of the selected records in terms of causative physical mechanisms are reviewed. This leads to the conclusion that even in well-documented cases, it is not possible to establish a robust correlation between specific physical mechanisms and large values of the residuals, and thus obtain direct physical constraints on εmax. Alternative approaches based on absolute levels of ground motion and numerical simulations are discussed. However, the choice of εmax is likely to remain a matter of judgment for the foreseeable future, in view of the large epistemic uncertainties associated with these alternatives. Additional issues arise from the coupling between εmax and σ, which causes the truncation level in terms of absolute ground motion to be dependent on the predictive equation used. Furthermore, the absolute truncation level implied by εmax will also be affected if σ is reduced significantly. These factors contribute to rendering a truncation scheme based on a single εmax value impractical.
Subfields: Civil and Structural Engineering
View Paper: https://www.semanticscholar.org/paper/9430a290dfba8a0e2fad3f8dda5791040427a778
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In Civil and Structural Engineering
Citations in the corpus
- Statistical Tests of the Joint Distribution of Spectral Acceleration Values (2008, result): “This is consistent with the findings of other researchers examining large data sets (Bommer et al., 2004; Abrahamson, 2006; Strasser et al., 2008).”