A seismic restraint is a cable, strap, or bracing system that prevents HVAC equipment movement during earthquakes or extreme structural motion. These restraints limit equipment displacement, prevent collision with adjacent equipment, and protect connections from stress. Seismic restraints are required by code in earthquake-prone regions and high-risk occupancies.
Restraint Types and Specifications
Common seismic restraints include cable assemblies with turnbuckles, adjustable steel straps, and rigid bracing frames. ASCE 7 standards specify restraint strength based on seismic acceleration coefficients and equipment mass. Typical horizontal restraint force requirements range from 0.4g to 0.8g of equipment weight. All fasteners must be rated for corrosion resistance, particularly in coastal regions.
Code Requirements and Installation
International Building Code (IBC) and ASCE 7-22 mandate seismic restraint design and installation. Restraints must anchor to structural members capable of withstanding calculated forces. Installation height and spacing prevent equipment tipping or shifting. Documentation and inspection certification are required for compliance.
Critical Applications
Seismic restraints protect rooftop units, chillers, fan coil units, and ductwork systems. They are essential in hospitals, emergency response facilities, and structures in Seismic Design Categories D, E, and F. Proper restraint design prevents secondary damage, maintains equipment operation, and ensures occupant safety.