A study on the structural strength has been performed on a semi-submersible configured with rectangular hulls having six columns and two pontoons sized 24173 tons in displacement and notionally to be operated in Natuna Sea. In the first stage of this study a hydrodynamic analysis is carried out to observe its motion responses due to wave excitations. This is then followed by evaluating the global structural responses in the form of shear forces and bending moments.In this respect two conditions are observed namely hogging and sagging under the head sea waves. Two wave characteristics are considered in the evaluation the first is the wave of length similar to the structure length which is 107 m and the second is the 100-year recurrence wave for the Natuna Sea. The shear forces and bending moments as the results of global structural response are then implemented in the second stage of the study that is on the structural strength analysis using a FEM tool. A certain boundary condition is defined and further the shear forces and bending moments are distributed on the appropriate nodes of the structural models. In this particular analysis three different semi-submersible structural models are investigated namely without deck structure with a rigid beam deck and with a smeared deck structure. Results of the FEM show the maximum stress for those three different structures are as high as 201 Nmm2 155 Nmm2 and 121 Nmm2respectively. Eventually it is found that the location of the maximum stress are different for the three models. In the case of model without deck maximum stress is found to be at the vicinity of the transverse beam near the deck level at the third column. In the case of the model with rigid deck the maximum stress develops at the connection between the third column and pontoon. Whereas in the case of the model with smeared deck maximum stress appears at the transverse beam of the pontoon below the first column.
semi-submersible, rectangular hulls, global structural response, structural strength
: Lambung kapal
: 623.84 Adi s
Source Article of Proceedings
Coverage ITS Community
Rights The 9th International Conference on Marine Technology MARTEC