Study On Analysis Models Of Offshore Jacket Platform With Storage Tank

Offshore jacket platforms with storage tank have been widely used in offshore oil exploitation. When offshore platforms with storage tank subject to dynamic loads such as wave or earthquake and so on, its dynamic characteristics is different from common offshore platforms due to the existence of liquid in the tank. The destruction of the platform would cause catastrophic disasters. Therefore, it is necessary to carry out the research on interaction between the tank and the liquid inside the tank.Firstly, the theory of Housner lumped mass is adopted to simulate the dynamic interaction between the tank and the liquid inside the tank. Governing equations of motion and discrete equations of finite element are derived to study the response of offshore jacket platform subject to wave and earthquake. Finite element model considering pile and soil interaction is established. The effects of liquid depths in the tank, seismic input directions, the types of seismic wave and dynamic load types on dynamic response of offshore jacket platform are analyzed.Secondly, based on the theory of fluid and structure interaction, finite element discrete equations of offshore jacket platform with storage tank are derived as the format of displacement and pressure (u_i, p). Finite element model considering pile and soil interaction is established as well. The effects of liquid depths in the tank, seismic input directions, the types of seismic wave and dynamic load types on dynamic response of offshore jacket platform are studied.Finally, comparison between Housner lumped mass model and fluid-structure interaction model are carried out. The results of displacements, stresses and natural frequencies show that both Housner lumped mass model and fluid-structure interaction model could be used to analyze dynamic response of offshore jacket platform with oil tank in an acceptable precision.For preliminary design, Housner lumped mass model is recommended to analyze jacket platform with storage tank in order to save calculation time. For detailed design, fluid-structure interaction model is suggested to use, which can obtain results of both jacket platform and oil tank.