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

How to select a limited number of ground motion records (GMRs) is an important challenge for the non-linear analysis of structures. Since epsilon (ε_Sa) 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 ε_Sa 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 ε_Sa and the peak ground velocity epsilon (ε_PGV). It is shown that η, as a non-linear response predictor, is remarkably more efficient than the well-known and convenient parameter ε_Sa. 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.