MIL-HDBK-1191
geology and soil conditions; past historical earthquake data; and statistical
methods used for calculation in determining the design seismic ground motion.
6.8
Evaluation of Existing Health Facilities. Determination of the
economical feasibility of seismic upgrade requires that the facility be
systematically evaluated, functional priorities established, and
rehabilitation measures and costs estimated before a decision is made
regarding the post-earthquake role to which the facility should be upgraded.
The approach to evaluating a facility will vary depending on several factors:
the level of seismic activity expected, age of the facility, type of
construction, and the number and configuration of buildings. Upgrade of all
portions of an existing facility and all of its systems to current seismic
criteria is usually not feasible or practical. Typically economic feasibility
limits upgrade to life safety performance levels.
6.8.1
Seismic Hazard Evaluation Considerations.
The following elements
should be considered in the overall evaluation.
6.8.1.1
Site Hazards Assessment. An assessment of geologic hazards at the
site will be done as indicated in Section 5, Structural Design.
6.8.1.2
Structural Design System Evaluation.
The seismic hazard
evaluation of an existing health care facility buildings Structural Design
system, including when an evaluation must be done and the criteria that will
control the evaluation, are given in Section 5, Structural Design.
6.8.1.3
Architectural Considerations. Buildings with irregular layouts
and configurations (such as U, L, T, E, H, or cross-shaped buildings) or
buildings with major setbacks are difficult to strengthen and potentially
hazardous and may be cost prohibitive. Overhangs, unbraced parapet walls,
gables, balconies, terra-cotta roof tile, and rigidly mounted glazing are
hazardous and endanger life safety. The following interior features must also
be evaluated:
a. Ceiling systems, in particular lay-in acoustical ceilings, are
extremely vulnerable to earthquake motions and forces.
b. Partitions and walls in relatively flexible buildings must be
checked, because provisions usually have not been made to prevent interaction
between the frames and partitions.
c. Egress doors, which are normally closed, tend to be immobilized
by binding the door frame during an earthquake. Their construction details
must be carefully reviewed to determine whether their operation will be
impaired.
d. Light fixtures and methods of suspension must be checked,
because pendant fixtures and fixtures recessed in lay-in acoustical ceilings
are particularly vulnerable.
e. Stairwells which are the only method of communication between
floors and vertical egress within the facility following an earthquake must be
checked. Structural Design adequacy of exterior stair tower structures
attached to the main structure to prevent separation during seismic shock must
also be checked.
6.8.1.4
Fire Protection Considerations. Evaluate the site water supply
system, including its vulnerability to earthquake damage, points of on-site
6-4
Previous Page
