MIL-HDBK-1191
Section 6:SEISMIC DESIGN
6.1
Introduction. This Section provides criteria for permanent
military health care facilities. Base seismic design requirements upon the
level of operation, or seismic performance objective, as defined in TI 809-04,
required for a particular health care facility following an earthquake.
Seismic performance levels vary from life safety (intended to reduce the
likelihood of injury and loss of life) to a complete post-earthquake
operational capability (defined as immediate occupancy in TI 809-04). The
required level of seismic performance for a facility will be as directed by
the Contracting Officer, determined in coordination with the Design Agent and
the Using Military Department Representative for a specific project.
6.2
Health Care And Design Requirements. The designation of seismic
performance objective for a particular health care facility will depend upon
the seismic use group, the seismic performance level, and the level of design
ground motion as defined in TI 809-04. Certain health care facilities may
require only key areas to be operational after an earthquake. Other health
facilities may require only a life safety level of performance. Design
requirements may include the preservation of essential utility systems such as
ventilation, electricity, water supply, waste systems, steam distribution,
medical gases, vacuum, medical air, and communications. Design utility
systems to permit isolation of damage by shutoff of damaged areas and
operation of systems at a reduced capacity.
Seismic Performance Levels. The Using Military Department will
6.3
determine based upon criticality of facility function the performance level
required for a medical facility. The following levels of seismic performance
are defined with respect to operational mission, disaster preparedness and
medical post-earthquake needs:
6.3.1
Life Safety Level. This level, which generally applies to
existing health care facilities, is the minimum requirement of seismic upgrade
or alteration projects. The essential requirement is to reduce the likelihood
of injury or death to personnel by providing a structure with a margin of
safety against collapse. Existing health facility structural systems will be
evaluated according to the requirements in TI 809-05 as given in Section 5,
Structural Design. This evaluation will also include both geologic site
hazards and the anchorage and lateral support of mechanical, electrical,
architectural and other non-structural elements whose damage will threaten the
life safety of occupants or might block safe means of egress. When an
existing Structural Design system does not meet these requirements, the system
will be strengthened according to the requirements in TI 809-05 as given in
Section 5, Structural Design. With this level of design, the health care
facility requires post-earthquake evacuation, with post-earthquake medical
operations dependant upon outside assistance. No specific time is specified
for re-occupancy and utilization for this class of structure.
6.3.2
Partial. The partial operational level, which is equivalent to a
safe egress Structural Design performance level as defined in TI 809-04, may
apply to either new or existing facilities. These requirements will generally
apply to new facilities to be located in areas where the design spectral
existing facilities where the design spectral response acceleration at short
periods (SDS) is greater than 0.167 but less than 0.33. In this category,
critical spaces, laboratories, radiology, CMS, supply storage, and Nuclear
Medicine must be designed to continue in operation following a design
earthquake. In those areas, fixed equipment, vertical transportation, and
6-1
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