A new indicator of elastic spectral shape for the reliable selection of ground motion records

Mehdi Mousavi, Mohsen Ghafory-Ashtiany, Alireza Azarbakht

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)


How to select a limited number of ground motion records (GMRs) is an important challenge for the non-linear analysis of structures. Since epsilon (εSa) is an indicator of spectral shape, which has a significant correlation with the non-linear response of a structure, the selection of GMRs based on the hazard-related target εSa is a reasonable approach. In this paper, an alternative indicator of spectral shape is proposed, which results in a more reliable prediction of the non-linear response for the structures with the natural period of 0.25 to 3.0s. This new parameter, named eta (η), is a linear combination of εSa and the peak ground velocity epsilon (εPGV). It is shown that η, as a non-linear response predictor, is remarkably more efficient than the well-known and convenient parameter εSa. The influence of η-filtration in the collapse analysis of an eight-story reinforced concrete structure with special moment-resisting frames was studied. Statistical analysis of the results confirmed that the difference between ε-filtration and η-filtration can be very significant at some hazard levels. In the case of this structure, the resulting annual frequency of collapse was found to be lower in the case of η-based record selection, in comparison with the ε-based record-selection approach.

Original languageEnglish
Pages (from-to)1403-1416
Number of pages14
JournalEarthquake Engineering and Structural Dynamics
Issue number12
Publication statusPublished - 18 Jan 2011
Externally publishedYes


  • collapse capacity assessment
  • epsilon
  • eta
  • ground motion record
  • hazard level
  • spectral shape


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