Special Considerations for Existing Facilities

DOE-STD-1020-2002

Existing facilities should be evaluated for DBE ground motion in accordance with the

guidelines presented earlier in this chapter. The process of evaluation of existing facilities

differs from the design of new facilities in that, the as-is condition of the existing facility must be

assessed. This assessment includes reviewing drawings and making site visits to determine

deviations from the drawings. In-place strength of the materials should also be determined

including the effects of erosion and corrosion as appropriate. The actual strength of materials is

likely to be greater than the minimum specified values used for design, and this may be

determined from tests of core specimens or sample coupons. On the other hand, erosive and

corrosive action and other aging processes may have had deteriorating effects on the strength of

the structure or equipment, and these effects should also be evaluated. The inelastic action of

facilities prior to occurrence of unacceptable damage should be taken into account because the

inelastic range of response is where facilities can dissipate a major portion of the input

earthquake energy. The ductility available in the existing facility without loss of desired

performance should be estimated based on as-is design detailing rather than using the inelastic

energy absorption factors presented in Chapter 2. An existing facility may not have seismic

detailing to the desired level and upon which the inelastic energy absorption factors are based.

Evaluation of existing facilities should begin with a preliminary inspection of site

conditions, the building lateral force-resisting system and anchorage of building contents,

mechanical and electrical equipment and distribution systems, and other nonstructural features.

This inspection should include review of drawings and facility walkdowns. Site investigation

should assess the potential for earthquake hazards in addition to ground shaking, such as active

faults that might pass beneath facilities or potential for earthquake-induced landslides,

liquefaction, and consolidation of foundation soils. Examination of the lateral force-resisting

system, concentrating on seismic design and detailing considerations, may indicate obvious

deficiencies or weakest links such that evaluation effort can be concentrated in the most useful

areas and remedial work can be accomplished in the most timely manner. Inspection of

connections for both structures and equipment indicates locations where earthquake resistance

might be readily upgraded.

Once the as-is condition of a facility has been verified and deficiencies or weak links

have been identified, detailed seismic evaluation and/or upgrading of the facility as necessary

can be undertaken. Obvious deficiencies that can be readily improved should be remedied as

soon as possible. Seismic evaluation for existing facilities would be similar to evaluations

performed for new designs except that a single as-is configuration is evaluated instead of several

configurations in an iterative manner (as is often required in the design process). Evaluations

should be conducted in order of priority. Highest priority should be given to those areas

identified as weak links by the preliminary investigation and to areas that are most important to

personnel safety and operations with hazardous materials.

As discussed in Chapter 2, the evaluation of existing facilities for natural phenomena

hazards can result in a number of options based on the evaluation results. If the existing facility

can be shown to meet the design and evaluation criteria presented in this standard and good

seismic design practice had been employed, then the facility would be judged to be adequate for

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