Abstract
Structural reliability analysis of a pontoon -type very large floating structure surrounded by a gravity-type breakwater is performed for the extreme wave condition considering the failure of breakwater as well as that of the floating structure. Bending and shear collapses of the cross s ection are considered as possible failure modes for the floating structure, while an overturning failure for the breakwater.
The probability of overturning of the breakwater and the probability distributions of the transmitted wave height with and without failure of the breakwater are evaluated based on the statistics of the extreme wave height in Tokyo Bay. The ultimate bending and shear strengths of the floating structure are calculated using the Idealized Structural Unit Method (ISUM) and FEM. Based on these results, the probability of failure of the floating structure considering the overturning of the breakwater is calculated and compared with the target safety level.
It has been shown that the considered floating structure is most likely to fail in th e bending collapse mode in transverse waves and the corresponding safety level satisfies the target level.
