Rotation Procedure

In cases when the records need to be rotated to Fault Normal/Fault Parallel orientation before being applied to the structure, the user may follow one of several methods.

Since the structure primary axes will generally not be aligned with the controlling fault, an additional rotation (beyond rotating to FN/FP) will usually be required, representing the angle between the FN or FP direction and the structure's axes.

As an example, when the analysis is performed in the software Perform-3D, there are different ways to specify the record rotation as follows:

1.Directly specify and define the final angle of rotation in QuakeManager. No additional angle will be defined in Perform-3D.

2.Rotate the records for Fn/Fp in QuakeManager and apply an additional angle of rotation in Perform 3D (angle between building principal axis and Fault orientation). In this case, the same angle will be applied to all records.

3.Do not rotate the records in QuakeManager, and apply rotation angle in Perform-3D. In this case, a different angle will need to be calculated for each record.

It is recommended that users use method 2 or 3 above, as they can help in simplifying the process of defining ground motions in Perform-3D and avoiding potential errors when calculating rotation angles for different records.

The chart below summarizes the record rotation process as follows:

Figure: Different Methods of Rotating Records for Use in Perform-3D

The figure below presents the steps of records rotation in QuakeManager as follows:

1.Select and Scale records

2.Select one or more record(s) from the generated suite

3.Select the Rotate and Scale Tool from the Records Ribbon

Figure: Rotation steps in QuakeManager

Under Basic Options, the user may choose the suitable option for rotating the selected records:

•Option 1: Rotate the selected record(s) to Fault Normal or Fault Parallel, export the records and apply an additional angle in Perform 3D

•Option 2: Rotate the record(s) to Fault Normal and define an angle measured from clockwise direction

Note: Users may export the records from QuakeManager unscaled, and apply the generated scale factors in Perform 3D, ETABS, SAP2000, etc.