Rational Determination of Design Wave using Combined Design Load Parameters (DLP) on Semi- Submersible with Twin Pontoon Type

摘要

This paper proposes a new approach to determine and verify design waves using the combined design load parameters (DLP) for semisubmersible with twin pontoon type, which can present the combination of the split force with torsion or longitudinal shear force. Several methodologies have been used to select the combined DLP by some engineering companies and classification rules. However, there are few explicit statements of the back-up references of the methodologies used on classification rules and the project specific reports provided by engineering companies. The comparison of newly proposed methodology and the existing three (3) methodologies has been implemented by the data of global load and resultant FE analyses. And an assessment has been followed to ensure whether the structural stresses on the semi-submersible Hull can be confirmed in accordance with classification rule and previous project experiences. In this paper, two combined DLPs are taken into account, one is defined as the case when longitudinal shear force and split force are maximized as far as possible (longi. shear split) and the other is the case when torsion and split force are maximized at the same time (torsion split). The two(2) combined DLPs could not be extracted directly by superposing corresponding linear RAOs through hydrodynamic analysis.