A New Energetic-Based Ground Motion Selection and Modification Algorithm

Abstract eng:
This paper presents a new ground motion modification and selection procedure that will be used for performing the response history analysis of structures. Nowadays, the availability of large ground motion databases allows performing time history analysis using real ground motion records. Since the main goal of response history analyses is to predict the dynamic behavior of structures, the most critical issue is the selection of a set of ground motions that determines a low variability of structural response. The proposed selection and scaling procedure approach derives from an energetic comparison at different frequency ranges of the horizontal component of the ground motion. The Conditional Mean Spectrum is used as target spectrum and only the records providing a relevant and effective contribution to the hazard of the site are considered. A set of ground motion with the same hysteretic energy demand can be obtained by matching the acceleration of the target spectrum at the period of interest T ref and selecting only the scaled spectra having an equal Housner intensity in the period range 0.2T ref -2T ref . In detail, the selection procedure consists in searching the set of horizontal components for each frequency band using an index which depends on the shape of the energy-frequency trend and of its dispersion around the mean value. This procedure generates a set of records which are spectrum compatible, having a similar hysteretic energy demand and a very low dispersion around the mean value. Low variability of the damage index values can be observed. As a result, this new approach allows selecting a set of spectrum compatible ground motions according to the frequency content and the expected structural damage for a given hazard scenario.

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