Telecommunications equipment in some North American networks must conform to hardware requirements to avoid damage or malfunction imposed by environmental stressors such as a seismic event.
The Network Equipment Building System (NEBS) created the Telcordia GR-63-CORE standard (formerly Bellcore) that defines the spatial and environmental criteria for equipment in these regions.
The GR-63 are general requirements and only involve the physical requirements for building equipment. Other design requirements, such as electrical requirements, are provided in other documents.
The VibrationVIEW software can run earthquake tests that meet the Telcordia standard and other earthquake time history waveforms.
Seismic Vibration Testing
Bellcore/Telcordia GR-63 Criteria
GR-63-CORE defines operation, storage, and transportation criteria in the event of a shock, vibration, or earthquake. The standard provides the required response spectrum and a field representative of time-history data.
The test engineer must survey the permanent structural and mechanical damage following the test. The standard defines permanent structural damage as the deformation of any load-bearing element of the equipment or any connection failure. Mechanical damage is any dislocation or separation of components. For frame-level testing, any permanent structural or mechanical damage constitutes a failure.
The engineer must also verify functionality immediately before and after a test. Hardware replacement during testing is not permitted. According to the standards, “The equipment shall sustain operation without replacement of components, manual rebooting, or human intervention.”
Example of the Process
The process for running the test standard may look as follows:
- Perform a swept sine survey.
- Verify the functionality and condition of the device under test.
- Subject the equipment to the provided waveform.
- Record the displacement and acceleration data.
- Inspect the equipment.
- Record any reductions in anchor or fastener torque.
- Re-verify the equipment.
- Repeat steps 1-7 for the X, Y, and Z-axis (for a single-axis shaker).
- Generate a test report.
Typical items in a test report include duration and number of exposures, the status of the device under test after visual examination, and response time histories and information processed.
User-Defined Transient Software
Vibration Research controllers can run an earthquake test with a Bellcore/Telcordia transient time waveform using the VibrationVIEW Transient Waveforms Control software. The test engineer can upload the time history data to the software, schedule several synchronous tests, and configure the SRS parameters.
Transient waveform control can be used for seismic testing or any industry where short-duration, high-amplitude transient events are likely to occur. It allows users to replicate time-history files and have better control over recorded events.
Modified Time History Waveform
In VibrationVIEW, the user can make minor adjustments to the original time history file to meet or exceed the required response spectrum. The software can employ adaptive SRS control, so the user does not need to modify the wavelet table to compensate for structural resonances.
Seismic Vibration Testing
Test engineers can evaluate structural design with VR’s leading-edge vibration control systems and reliable, user-friendly software. Download a free demo and put the software to the test.
Interested in learning more about seismic testing with Vibration Research systems? Contact us!