Probability of Failure of Damaged Ship Structures - Phase 3

Abstract : The methodology developed in Phase II for assessing the reliability of damaged ships is applied to a damaged ex-HMCS Nipigon. The midship section of the vessel is used in the analysis. The statistics of the maximum damaged length and the maximum penetration depths are determined with SIMCOL and COMPASS. Operational profiles for the damaged vessel are defined and WAVALOAD is used to compute the response amplitude operators, RAOs, of the waves on the vessel. The extreme values of the wave loads are also calculated and calibrated, and TRIDENT is used to estimate the still water bending moments. The ultimate bending moment capacities of the intact and the damaged vessel are calculated using ULTMAT. The damage size feature of ULTMAT is used ot estimate the ultimate bending moment capacities interaction curves for damage sphere sizes of 2 m 3 m, 4 m, 5 m, and 6 m. These values are then used to determine the mean values, standard deviations and interaction coefficients for the damaged vessel. The linear and interaction equations limit state functions are defined and employed in COMPASS to estimate the reliabilities and the important factors fo the random variables. Both the first order reliability method, FORM, and the Monte Carlo Simulation method, MCS, are used.