30 September 1999
Table 1-1. Seismic Use Groups
Seismic Use Group
Occupancy or Function of Structure
I. Standard Occupancy Structures
All structures having occupancies or functions not listed above.
II. Special Occupancy Structures
Covered structures whose primary occupancy is public assembly with a capacity
greater than 300 persons*.
Daycare centers with a capacity greater than 150 persons.
*ASSSEMBLY AREA GUIDELINES
Educational buildings through the 12 grade with a capacity greater than 250
persons or 465 m (5,000 ft ) classroom space.
Assembly areas, concentrated (without fixed
seats) -Single room 195 m (2,100 ft ) or more.
Buildings for colleges or adult education schools with a capacity greater than 500
students or 929 m (10,000 ft ) of classroom space.
Churches and chapels
Lobby accessory to assembly occupancy
Medical facilities with 50 or more resident incapacitated patients, but not
otherwise designated as Seismic Use Group IIIE facility, or 372 m (4,000 ft ) of
W aiting area 84 m (900 ft ) or more
Assembly Areas, less concentrated use
Jails and detention facilities.
Single room 418 m (4,500 ft ) or more
All structures with occupancy capacity greater than 5,000 persons.
Structures and equipment in power-generating stations and other public utility
facilities not included in Seismic Use Group IIIE, and that are required for
W ater treatment facilities required for primary treatment and disinfecting of
W astewater treatment facilities required for primary treatment.
Facilities having high value equipment, when justification is provided by the using
III H. Hazardous Facilities
Structures housing, supporting or containing sufficient quantities of toxic or
explosive substances to be dangerous to the safety of the general public if
III E. Essential Facilities
Facilities involved in handling or processing sensitive munitions, nuclear
weaponry or materials, gas and petroleum fuels, and chemical or biological
Facilities involved in operational missile control, launch, tracking or other critical
Mission-essential and primary communication or data handling facilities.
Hospitals and other medical facilities having surgery and emergency treatment
Fire, rescue, and police stations.
Designated emergency prepared centers.
Designated emergency operations centers.
Designated emergency shelters.
Power-generating stations or other utilities required as emergency back-up
facilities for Seismic Use Groups IIIE facilities.
Emergency vehicle garages and emergency aircraft hangars.
Designated communications centers.
Aviation control towers and air traffic control towers.
W aste treatment facilities required to maintain water pressure for fire
Essential facilities are those structures that are necessary for emergency operations subsequent to a natural disaster.