Application of the finite element method to off-shore structures

Abstract The merits of finite element methods in connection with the design of offshore structures are discussed using the Ekofisk Tank as an example. Various design approaches and procedures are evaluated on the same basis and some of the experiences gained are mentioned. The conclusion is drawn that the finite element method is a very powerful tool in the evaluation of new designs, but to be successful, it requires good planning and experienced personnel. The procedures presently applied for determination of wave loads do not represent a very realistic modelling of the actual storm conditions. To show what improvements can be made in this field, an outline of how the irregular wave system may be formulated and how the calculated loads may be applied in the stress analysis is given. The procedure is described with reference to a semisubmersible drilling platform but the principle may be applied to any offshore structure.