A simplified methodology for dynamic responses of cross-decks of trimarans under slamming loads

The design principle of the hull structure is to ensure sufficient strength and avoid excessive waste of materials. The equivalent dynamic coefficients (EDC) possess the advantages of both static analysis and dynamic analysis in engineering. However, there is still no clear method for determining the EDC of a trimaran. In this work, the EDC of the cross-decks are chosen as the research objects. The EDC of the plate, longitudinal girders, and transverse frame of the cross-decks are calculated respectively. A method considering material nonlinearity and a method considering transverse bending moment (TBM) are proposed, and the effect of elastic-plastic material and TBM on EDC is presented. Results show that it is feasible to use the EDC to analyze the trimaran under slamming loads. Besides, the EDC of different parts of the trimaran is different, hence it is not recommended to use the fixed value given by the ABS rules.