On the influence of the parametric roll resonance on the principal wave-induced loads

A safer and more reliable ship structure design needs continuous efforts in improving the estimation of the en-vironmental critical loads. Nowadays, linear and non-linear time domain seakeeping codes represent the two main standards for direct calculation of ship motion and structural loads in waves. Although linear analysis remains valuable for long-term statistical analysis, it cannot model some motion instabilities such as the para-metric roll resonance. Full-scale observations and model tests have shown that the phenomenon of parametric roll resonance can occur in head, following and oblique seas. Despite several numerical and experimental stud-ies have been carried out on parametric roll regarding ship motion and stability in waves, not sufficient atten-tion has been given to its influence on induced loads for a ship. In this paper, we aim to qualitatively assess the variation of the internal loads in waves of a containership, in presence of parametric roll resonance. A hy-brid non-linear simulation model in 6 degree of freedom will be used to evaluate ship dynamics in waves and to calculate shear force and structural moment distributions. In particular, the nonlinear restoring and non-linear Froude-Krylov action are implemented, together with non-linear inertial loads. Numerical time domain simulations will be carried out for a containership, in regular waves.