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Records may be rotated from their original as-recorded orientation to any desired orientation. Some records may also be rotated to their fault-normal (FN) and fault-parallel (FP) components. .
In general, it is assumed that the angle corresponding to the FN/FP directions will lead to the most critical structural response, or such a rotation may be prescribed by some code requirements. Some codes require that records be rotated to their FP/FN orientations before being applies to a building, if the building is within the near-fault zone of a significant seismic fault.
This is a complex issue, but it is worth noting that ground motion intensity and damage potential are significantly affected by:
•The faulting mechanism
•Direction of rupture propagation relative to the site
•Possible static deformation of the ground surface associated with fling-step effects
Near-fault records are also likely to exhibit a pulse (fling) effect. Near-source effects cause most of the seismic energy from the rupture to arrive in a short coherent long-period pulse of motion in the FN (and/or FP) direction(s).
QuakeManager provides Basic and Advanced options and parameters for defining very specifically how the rotation should be performed and also allows for simultaneously scaling the records. Users may select a record or multiple records in a suite, and choose the Rotate & Scale option in the Export part under the Record Ribbon. The records will be exported to a default location or a folder of the user's choosing.
Using the Basic Options, users can simply rotate, scale and save the new record. Users can also click the Advanced Options to adjust the saving directory, modify record name, and select the suitable H1/H2 and Fn/Fp component orientations.
NOTE that the user may also export the selected record files using the Rotate and Scale tool. The user can set the basic options, and under the advanced option, the user can specify the location of the files on the disk and export them.
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