Hull sizing system for tension leg platform (TLP) has been developed by using optimization algorithm. Hull sizing work is vital at the initial design stage of the offshore platforms. It is the driver towards a successful execution of a good design. In order to achieve the objective of producing an efficient and cost effective design, optimization of the hull configurations is very important. An optimized hull needs input from various criteria such as global performance, stability, strength, constructability, installation, etc. During the process of optimizing the design, it is inevitable that the hull configurations go through a number of iterations. Thus, the hull sizing program is developed by using optimization algorithm in order to solve multi-variable problem in the effective way in producing an efficient design in terms of performance, constructability and cost.
The principal dimension of the hull (column and pontoon size) and tendon size are the variables to be optimized. The objective function to be minimized is the sum of the of hull and tendon material weight. At each iteration of the optimization process, the program evaluates the global performance criteria, stability criteria, and simplified global strength criteria. The frequency-domain analysis method is used to perform the global performance analysis. The hydrodynamic coefficients are calculated by applying the boundary element method. Global strength analysis is carried out by using a beam model. Metocean data, water depth, riser information and topside information, such as weight, center of gravity and wind force coefficients, are input constant. A simulated annealing method is used for the optimization algorithm of the hull dimension and tendon size.
The program is being tested for a conventional TLP. The optimized hull shape provided in this program is in line with the existing TLP configurations. Henceforth, the program will be further studied and will be verified to improve its practical utility.