Jack-up platform leg optimization by topology optimization algorithm-BESO

Abstract

Jack-up platforms are widely used for the offshore oil and gas exploration, constructions and offshore wind farms. The jack-up platform legs are import component, which not only support the whole weight but also withstands various external loads, such as wind, current and wave load. A topology optimization algorithm-BESO (bi-directional evolutionary structural optimization) is proposed in this paper for the jack-up leg optimization. Based on the sensitivity analysis, the optimization strategy with sensitivity filtering and updated have been applied. And a simple numerical example is used to verify the proposed optimization method. A case jack-up platform is introduced to implement the leg structure optimization. After a series of iterations, a new leg structure is obtained. And the ultimate analysis, Eigen analysis and buckling of optimized leg structure optimized structure are all discussed compared with the traditional structures (K-type, the reverse(rev) K-type and X-type). To further evaluate the performance of the optimized leg structures, an experiment test is designed in the wave tank considering the current and wave load. Also, the optimized leg structure and the traditional ones are all manufactured to perform the experiment. The results show that the optimized leg structure has better ultimate bearing capacity, Eigen analysis and dynamic response with lighter weight under the same environmental loads. It is indicated that the BESO topology method is superior in finding best structure of the jack-up platform leg.