Influence of different wave load schematisation on global ship structural response

Today, direct calculation using complete/full ship finite element (FE) models is the standard practice in structural design of complex ships (cruise and passenger ships, Ro-Ro, container ship, etc.). In the early design stage, time is one of the main drivers; therefore, linear static FE analysis is a common practice and considerable simplification in modelling (structural and loading) is needed to maintain time efforts within the required targets. Classification societies cover all those aspects through different design guidelines that help structural designers to streamline the design process and make rule-requested structural verification of the proposed design. Structural modelling aspects are well defined and established, but for the wave load modelling some questions arise. Wave pressure distribution can be defined using direct wave calculations (e.g. the panel method) or using the rule formulae definition. This paper presents a benchmark study carried out by the ISSC2018 Committee II-1 Quasi-Static Response. The objective was to investigate and compare alternatives to discretize and implement rule-defined wave loads from different classification societies on global FE models, and its impact on the global structural response. Results from calculations are presented on two ship types, a typical cargo ship and a passenger ship. Findings highlight the importance of identifying the lowest level of simplification in order to capture physical phenomena while minimizing errors and inaccuracy in direct structural analyses results.