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A building located in San Francisco, California, is classified as a near-fault site as the following criteria are satisfied:
•Distance between the building and the San Andreas fault equals 5.4 km (<15 km)
•Historically, this fault generated events with Mw > 7
The figure below presents the site characteristics showing that the building satisfies the near-fault conditions of ASCE 7-16. The building x-axis has a 33° (clockwise) angle from the San Andreas Fault Normal.
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Figure: Site characteristics
A record (H-E04140) was generated using QuakeManager having the following characteristics:
•Mw = 6.53
•drup = 7.05
•PGA = 0.57
•Tpulse = 4.79
•Site Class: D
The user have two options to rotate the generated record as follows:
•Option 1: Rotated to Fault Normal
•Option 2: Rotated to Fault Normal + Angle (33° in this case)
The figure below shows that the as-record Ground Motion Record (red record) was rotated to Fn/Fp only in QuakeManager. An angle (-33°) was applied to the rotated record (green record) in Perform 3D to account for the building orientation. In this case, an angle of 33 degrees is applied in Perform-3D as shown.
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Figure: Rotation option 1
QuakeManager supports an alternative option in which users may rotate the records to Fn/Fp plus the angle of the building direction. This indicates that no additional angle shall be applied in Perform 3D. The rotated record (green record) to Fn/Fp was also rotated to an angle which resulted in the record (orange) having the building principal directions.
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Figure: Rotation option 2
Note that in both options above, an Acceleration Factor of -1 should be defined for the 2nd component in Perform-3D since th 2nd component in this case is 90-degrees CW from the 1st component.
The figures below shows the results of a generated (as-recorded) and rotated record using QuakeManager:
•Black record: As-record record
•Green record: record rotated to Fn/Fp
•Orange Record: record rotated to Fn/Fp + Angle
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Figure: As-recorded Component 1 of the generated record
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Figure: Record Component 1 rotated to Fault Normal
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Figure: Record Component 1 rotated to Fault Normal + additional angle
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Figure: As-recorded Component 2 of the generated record
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Figure: Record Component 2 rotated to Fault Parallel
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Figure: Record Component 2 rotated to Fault Parallel + additional angle
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