Parameter sensitivity of the excessive acceleration failure mode in second-generation intact stability

In this study, the parameter sensitivity of the level 1 and 2 assessments of the excessive acceleration failure mode in the International Maritime Organization second-generation intact stability was analyzed. Monte-Carlo simulations were conducted using the input parameter space, which was generated using a Gaussian distribution, and a variance-based sensitivity analysis was performed using the Monte-Carlo simulation results. The longitudinal and vertical positions of the check point, natural roll period, and roll decay coefficient were selected as input parameters for the level 1 assessment, whereas the roll damping coefficient and effective wave slope coefficient replaced the roll decay coefficient for the level 2 assessment. The results revealed that the highest total sensitivity index for the level 1 assessment was the natural roll period, which was 0.8, and the effective wave slope had a total sensitivity index of 0.5 for the level 2 assessment. This indicated that the uncertainty of the natural roll period was dominantly propagated to the resultant value of the level 1 assessment, while the effective wave slope coefficient was the most sensitive parameter in the level 2 assessment. The uncertainty in the input variable was found to cause the opposite decision if the resultant value was close to the criterion value under a given loading condition.