Assessment of bending and torsional moments on hull girder due to parametric roll: a case study for a containership

This paper presents a novel analysis of wave-induced hull girder loads acting on a ship in case of parametric roll. This phenomenon, usually investigated about stability issues, could have a high incidence on ship structures due to the development of large torsional loads. In this paper, a systematic analysis of wave-induced torsional moment and vertical bending moment is carried out for a containership prone to parametric roll resonance. The numerical estimation of torsional and vertical loads, in absence and in presence of parametric resonance is performed by means of a 6-DoF model, capable of simulating both ship dynamics and the corresponding wave-induced loads. The scope of this paper focuses on hull girder load estimation and discussion, with the aim to identify relevant scenarios involving parametric roll resonance. The obtained results show a relevant increase in torsional moment in presence of parametric roll resonance, together with large values of vertical bending moment.