(a) some components, although standard ones, are stronger than required
(b) there are built-in safety factors
(c) the “extra” capability will be available for only part of the equipment lifetime.
Time
Demand or Expectation
Intrinsic Design Capability
Performance Measure
Fig. 20.8 Demand exceeds capability
Maintenance
Action
Capability deterioration
with time
Time
Performance Measure
Demand
Fig. 20.9 Maintenance required to restore capability
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20 Human Resources Management for Infrastructure