Comparison of Postulated Failures with Performance Goals

DOE-STD-1020-2002

missiles. Each event in the sequence can be associated with a wind speed. All obvious

damage sequences should be examined for progressive failure.

3.3.4

Comparison of Postulated Failures with Performance Goals

Once the postulated failure sequences are identified, the SSC performance is compared

with the stated performance goals for the specified Performance Category. The general SSC

evaluation procedures described in Appendix B(Figure B-2) are followed. If an SSC is able

to survive wind speeds associated with the performance goal, the SSC meets the goal. If the

performance criteria are not met, then the assumptions and methods of analyses can be

modified to eliminate conservatism introduced in the evaluation methods. The acceptable

hazard probability levels can be raised slightly, if the SSC comes close to meeting the

performance goals. Otherwise, various means of retrofit should be examined. Several

options are listed below, but the list is not exhaustive:

(a) Add x-bracing or shear walls to obtain additional lateral load resisting capacity

(b) Modify connections in steel, timber or pre-stressed concrete construction to permit

them to transfer moment, thus increasing lateral load resistance in structural frames

(d) Install tension ties that run from roof to foundation to improve roof anchorage

(e) Provide x-bracing in the plane of a roof to improve diaphragm stiffness and thus

achieve a better distribution of lateral load to rigid frames, braced frames or shear

walls.

To prevent breach of structure envelope or to reduce the consequences of missile

perforation, the following general suggestions are presented:

(a) Install additional fasteners to improve cladding anchorage

(b) Provide interior barriers around sensitive equipment or rooms containing hazardous

materials

(d) Erect missile resistant barriers in front of doors and windows

(e) Replace ordinary overhead doors with heavy-duty ones that will resist the design

wind loads and missile impacts. The door tracks must also be able to resist the

wind loads.

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