Evaluation of the Cross Structure Design Wave Loads for a Trimaran

摘要

It was very important to obtain the cross structure design wave loads of a trimaran for its transverse strength in structure design. In order to study the cross structure design wave loads of a trimaran, its model test was performed in a seakeeping tank. The model test conditions were composed of regular and irregular waves in head and quartering seas. Splitting moments Msp, splitting shear forces Qsp and transverse torsional moments Mtt of the cross structure were measured in model tests. RAOs and statistical properties were analyzed in detail. According to analysis of the cross structure wave loads from model tests, deductions and rule calculations, the full amplitude wave height to the calculation of those transverse wave loads might be 6.0 meters in LR rule. To different transverse wave loads, the extrapolated result of design wave loads with dependability 99% of transverse torsional moments Mtt was greater than that from rule calculation. However, the deductions of splitting moments Msp and splitting shear forces Qsp were to some tune to rule calculations. It can be concluded that the evaluation methods from LR rules were nonconservative for the cross structure design of transverse torsional moments Mtt. This should be paid some attentions to ship designers in particular.