Stiffness Properties of Fixed and Guyed Platforms

For deep‐water offshore structures, the fundamental period of lateral vibration is a key factor influencing their design feasibility. This period can be controlled by a rational selection of the parameters governing the stiffness of these structures. These parameters and their relative significance in determining the stiffness properties have been identified. A mathematical springmass model to portray the stiffness behavior of platforms is introduced. Data are presented to show how stiffness properties can be rationally augmented. The conclusions of the aforementioned parametric studies are verified with reference to a fixed jacket platform in 450 m water depth. The participation of foundation flexibility in influencing stiffness is also investigated. Finally, a concept of insert piles and a strategy for designing deep‐water fixed jackets, and guyed towers for stiffness are introduced.