An earthquake-source-based metric for seismic fragility analysis

Alin Radu*, Mircea Grigoriu

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

6 Citations (Scopus)
231 Downloads (Pure)


The seismic fragility of a system is the probability that the system enters a damage state under seismic ground motions with specified characteristics. Plots of the seismic fragilities with respect to scalar ground motion intensity measures are called fragility curves. Recent studies show that fragility curves may not be satisfactory measures for structural seismic performance, since scalar intensity measures cannot comprehensively characterize site seismicity. The limitations of traditional seismic intensity measures, e.g., peak ground acceleration or pseudo-spectral acceleration, are shown and discussed in detail. A bivariate vector with coordinates moment magnitude m and source-to-site distance r is proposed as an alternative seismic intensity measure. Implicitly, fragility surfaces in the (m, r)-space could be used as graphical representations of seismic fragility. Unlike fragility curves, which are functions of scalar intensity measures, fragility surfaces are characterized by two earthquake-hazard parameters, (m, r). The calculation of fragility surfaces may be computationally expensive for complex systems. Thus, as solutions to this issue, a bi-variate log-normal parametric model and an efficient calculation method, based on stochastic-reduced-order models, for fragility surfaces are proposed.

Original languageEnglish
Pages (from-to)3771-3789
Number of pages19
JournalBulletin of Earthquake Engineering
Issue number9
Early online date1 Mar 2018
Publication statusPublished - 1 Sep 2018


  • Seismic fragility
  • Seismic intensity measures
  • Monte Carlo simulations
  • Stochastic reduced-order models
  • Earthquake risk

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