ssc-367 - Ship Structure Committee

A deterministic method is sometimes identified as probabilistic
analysis as the randomnessof the ocean environment is accounted for
by incorporatingthe wave spectra. Thus, dependingon how the loads
are generated, the fatigue analyses method may be identified as:
●
Deterministic - Single Wave
● Spectral - Regular Waves in Time-Domain
● Spectral - Regular Waves in Frequency-Domain
● Spectral - IrregularWaves in Time-Domain
● Spectral - Wind Gust
Further discussion on fatigue analyses parameters and analysis
sequence is presented in Sections 3 and 4, respectively.
2.3
SIGNIFICANCE OF FATIGUE FAILURE
An improperdesign may lead to an unacceptablecatastrophic fatigue
failure, resulting in loss of life and damage to the environment.
Non-catastrophic fatigue failures are also unacceptable due to
difficulty and cost of repairs as well as the need to increase
costly inspection and maintenance intervals.
Numerous marine structures of different configurations are in
operation. As illustrated on Figure 2-3, these structures may be
grouped as “mobile”or “stationary”,depending on their functional
requirement. Although mobile vessels/structurecan be moved to a
shipyard for repairs, the total cost of the repair includes
downtime. Stationary offshore vessel/structure inspections and
repairs are extremely costly due to on-location work and their
operating environment, yet the effectiveness of repairs is often
uncertain. Thus, for bothmobile and stationarymarine structures,
it is essential to consider avoidance of fatigue failure at every
phase of design and fabrication.
2-7