Why Is Seismic Restraint Needed?

The damaging effects of earthquakes are of significant concern in many areas of the world. Earthquake damage to inadequately restrained mechanical and electrical systems within buildings can be extensive. Mechanical and electrical equipment knocked off of its supporting structure due to earthquake-related building movement can threaten both life and property. The cost of properly restraining this equipment is insignificant compared to the associated costs of replacing or repairing the equipment and to the cost of system down-time as a result of seismic damage to the building services.

This site presents restraint systems which serve to limit the movement of equipment and to keep the equipment captive during a seismic event. Proper utilization of these systems can reduce the threat to life and minimize long-term costs due to equipment damage and associated loss of service.

A thorough analysis of seismic restraint hardware and seismic rated vibration isolators requires the consideration of four (4) aspects of the system:

  1. Attachment of the Equipment to the Restraint
    • The equipment must be securely attached to the restraint, and this attachment must demonstrate sufficient strength to withstand the imposed forces and to allow for transfer of seismic forces into the restraint.
  2. Restraint Design
    • The strength of the seismic restraint must be sufficient to withstand the equipment imposed forces. Kinetics offers a wide variety of restraints suitable for many different applications.
  3. Attachment of Restraint to the Building Structure
    • This attachment is typically via bolts, welds, or concrete anchors. In addition, the building attachment interface must be reviewed to ensure that it is capable of withstanding the imposed seismic forces. Typically this attachment is the 'weakest link' of the overall design, especially when embedded concrete anchors are used.
  4. Equipment Fragility
    • The ability of the equipment to continue to operate after being subjected to seismic force. Fragility information must be obtained from the equipment manufacturer and is not covered in this brochure.

Examples of properly restrained HVAC equipment surviving the 1994 Northridge earthquake unscathed. On the left is a rooftop installation directly next door to the collapsed parking garage in Northridge. On the right is a rooftop installation across from the I-10 collapse.

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