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The Resampling tool adjusts the number of data points and the time step (dt) of a ground motion record while preserving its total duration. The following relation is always satisfied:
newDt × newNumberOfPoints = originalDt × originalNumberOfPoints
This ensures that the record covers the same overall time span after resampling.
Also, this tool is typically used to reduce the number of data points (by increasing the time step) in order to reduce the analysis time in response history analysis.
Available options include:
•Time Step (dt) – Define the new time step to be applied to the record.
•Number of Points – Specify the desired number of points in the resampled record.
•dt Factor – Provide a scaling factor n, which sets newDt = n × originalDt for each record.
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Figure: Resample Dialog
The figures below present the resampling process for the A-STU record. The original (as-recorded) ground motion consists of 16,392 samples (the user can view the data series metadata from the record properties pane). The target number of samples desired is set to 10,000. After resampling, the resulting record contains exactly 10,000 points, as defined. .
The original and resampled acceleration time-histories are compared to highlight the effect of the operation. It should be noted that the "SamplesPerSecond" value is automatically updated since the total number of samples has changed, while the overall duration of the record remains unchanged.
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Figure: Resample operation
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Figure: A-STU record acceleration time-history before and after resampling
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