The main objective of the study was to develop a set of strong motion time histories suitable for seismic qualification testing of electrical substation equipment in accordance with the IEEE 693- 1997 standard. Although the objective deals with sh ake table testing of a particular class of equipment, many of the issues investigated are equally relevant to the dynamic testing of other types of equipment and components. This study was motivated by a desire to introduce a standard set of input motions in three orthogonal directions and thus achieve more consistency in earthquake simulator testing. The report focuse s on developing with a time domain spectral matching procedure an input strong motion based on a record of an actual earthquake, so that the spectrum-compatible strong motion time history preserves the non-stationary behavior of the actual record.
A selection of 35 three-component historic records from 18 earthquakes was analyzed and the records were compared by using several parameters. From the analysis, the best candidate for the input strong motion was selected and modified by adding non-stationary wavelets to the signal. The resulting strong motion time history preserves the non-stationary behavior of the actual earthquake record, while its response spectra envelop the IEEE target response spectra for a broad range of natural frequencies as required by the standard. The resulting strong motion time history is intended for use by testing facilities and will be considered for a future revision to IEEE 693.
Additional requirements for the input motion specification in the IEEE693-1997 are recommended.
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