Structural Reliability of Oil Tanker in the Adriatic Sea Damaged in Collision and Exposed to Combined Bending Moments

摘要

The aim of the paper is the assessment of structural reliability of oil tanker, damaged in collision accident in the Adriatic Sea and exposed to combined, horizontal, and vertical bending moments. Damage size is assumed based on the direct numerical simulation of the ship-ship collision. This is justified for some specific sea environments, as the Adriatic Sea, where ship sailing routes and representative ship types involved in accidents are known, so possible collision scenarios may be reasonably predicted. Residual bending moment capacity under combined bending moments (CBM) is calculated using regression equations developed based on non-linear finite element analysis. Still-water vertical bending moments are obtained by damage stability analysis for different collision scenarios that are generated by Monte Carlo (MC) simulations. Vertical and horizontal wave bending moments are determined by short-term response analysis of damaged ship in the Adriatic Sea, using transfer functions obtained by 3D panel hydrodynamic method. Monte Carlo time simulations are performed in order to study probabilistic load combination (LC) considering randomness of the wave process due to different phase angles. Limit state function is defined using interaction equation for damaged ship exposed to combined bending moments. Safety indices are calculated by FORM for each damage scenario by using Turk-stra's rule for load combination of vertical and horizontal wave bending moments. Such an approach enables to determine the safety indices for the most frequent damages and also to reveal the most critical situations resulting in the lowest safety indices.