Page 75 - Marine Structural Design
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Chapter 3 Loads and Dynamic Response for offshore Structures 51
N,, = Number of loading patterns
NF = Number of frequency points
NH = Number of wave headings
Figure 3.9 shows a deck plating at the mid-section. The stress FRFs at twenty-four incident
wave directions (refer to Figure 3.10) are calculated by using the 2D strip method. 3D
hydrodynamic and FE method can be used for general structural details.
Figure 3.9 Deck Plating at the Mid Cross-section
The spectral density function of the response (stresses or loads) to a wave spectrum using the
wave scatter diagram and the FRF, can be determined by:
where,
Sy (0) = Spectral density function for response x
S~(W, e,)= Wave spectral density function with wave spreading
@(e,,,)= Spreading function
S:(w,B,) = S:(w)O(B,)
where,
2)
S;(W) = Wave spectral density finction specified by (Hs, and @(e,) is expressed as:
